(dd13-14) anatomic sciences

Saad Alqahtani, Twitter @saaddes

lymphatic system Which of the following structures carry lymph into the node's subcapsular sinus, through the cortical sinus and into the superficial cortex and para-cortex?

efferent lymphatic vessels

afferent lymphatic vessels

both afferent and efferent lymphatic vessels

neither afferent o r efferent lymphatic vessels

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afferent lymphatic vessels

Lymph nodes are small oval bodies enclosed in fibrous capsules. Lymph nodes con-tain phagocytic cort ica l t issue (reticular t issue) adapted to fi lter lymph. Specialized bands of connective t issue, ca lled trabeculae, divide the lymph node.

Afferent lymphatic vessels carry lymph into the node's subcapsular sinus, through the cortical sinus and into t he superficial cortex and paracortex. Conversely, the lymph may travel d irectly from the cortical sinus into the medullary sinus. It is primarily in these cort ices and the medullary sinus that t he lymph is cleansed by macrophages, and antigens are presented and processed by lymphocytes, and plasma cells. The fil -tered lymph leaves t he node through the efferent lymphatic vessels, w hich merge through t he concave hilum and t ransport the lymph into efferent collecting vessels, which converge into larger vessels cal led lymph trunks (there are five major lymph trunks in the body). The thoracic duct receives lymph from three out of the four quad-rants of t he body; both lower quadrants and the upper left quadrant. The right lym-phatic duct receives lymph only from t he upper right quadrant.

Note: The thoracic duct receives lymph from three out of t he four quadrants of the body; both lower quadrants and the upper left quadrant. The right lymphatic duct re-ceives lymph only from the upper right quadrant.

Important: 1. The afferent lymphatic vessels enter on the convex surface of the node. 2. There are fewer efferent vessels than afferent vessels associated w ith a node. 3. The spleen, thymus, palatine, and pharyngeal tonsils do not have numerous af-ferent vessels entering them as do lymph nodes. 4.The paracortex is dominated byT-cells.

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Trabeculum Postcapillary (high ondotholial)

lary

cortex

Lymph node s tructure. The bean-shaped lymph node has a hilum into which blood ves-sels enter, and from which efferent lymphatics emerge. It has an investing capsule. Af-ferent lymphatic vessels penetrate the convex surface of the gland and drain into the subcapsular and medullary sinus system. The lymphoid parenchyma is subdivided into cortex, paracortex and medulla. The most prominent structures in the cortex are the lym-phoid follicles.

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(Reproduced wilh permission from Slcvcns. A. and Lowe J. H11mall Histology. cd 3. Elsev1er, Philndelpbia. 2005.)

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Area draining to right lymphatic duct

Right and left venous angles

OeCp cervical Right nodes

lymphatic -==~'.!\. duct --------LM subcl=~~=~--1--:"-~f":/o;"

vein Central and --

posterior axillary ~.e.:;..-+:JR"II~ nodes

Deep lymphatic

vessels Cubital

nodes

Area draining to horacic duct

Lymphoid system. Pattern of lymphatic drainage. Except for right superior quadrant of the body (pink), lymph ultimately drains into the left venous angle via the thoracic duel. The right superior quadrant drains into the right venous angle, usually via a right lymphatic duel. Lymph ty pically passes through several sets of lymph nodes, in a gen-erally predictable order, before it enters the venous system. 1Al

Reproduced wilh penmssion (rom Moore KL. Daile)' AF. andAgur AMR. Cliiiicaii)'OrienteJ Anatomy. cd 6. Wollcrs Kluwcr, Ballmtorc. 2010.

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lymphatic system Which of the following vessels are characterized by the presence of valves?

arterioles only

capil laries only

sinusoids only

veins only

lymphatics only

lymphatics and capil laries

lymphatics and veins

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lymphatics and veins

Primary lymphatic organs are responsible for the generation and selection of lymphocytes. These are the thymus and bone marrow. Secondary lymphatic organs include the tonsils, spleen, lymph nodes, appendix, which are responsible for the filtering component. There are also areas of diffuse lymphoid tissue throughout the body including MALT, GALT, and SALT (mucosa-, gut-' and bronchus-associated lymphoid tissue, respectively). GALT includes the tonsils and Peyer's patches. The common component to all lymphatic tissues is the presence of lymphocytes.

Functions of the lymphatic system: Returns tissue fluid to the bloodstream: when this fluid enters lymph capillaries, it is called lymph. Lymph is returned to the venous system via two large lymph ducts, the thoracic duct and the right lymphatic duct Transports absorbed fats: within the villi in the small intestine, lymph capillaries, called lacteals, transport the products of fat absorption away from the Gl tract and eventually into the circulatory system through the thoracic duct Provides immunological defenses against disease-causing agents: lymph filters through lymph nodes, which filter out microorganisms (such as bacteria) and foreign substances. Lymph nodes have also been shown to trap cancerous cells in the body.

1. Lymph contains a liquid portion that resembles blood plasma, as well as white blood cells (mostly lymphocytes) and a few red blood cells. 2. Lymph is absorbed from the tissue spaces by the lymphatic capillaries (which is a system of closed tubes) and eventually returned to the venous circulation by the lymphatic vessels, after lymph flows through the filtering system (lymph nodes). 3. In the upper limb, a hallmark of lymphatic vessels is that they follow the veins. 4.The lymphatic system does not have a central pump to move lymph throughout the body. "Instead, the lymphatic system depends on the contractions of skeletal muscles, the presence of valves in lymphatic vessels (similar to those in veins), breathing, and simple gravity to move flu id throughout the body~

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The Lymphatic System

Cervical lymph nodes

Thymus

Right lymphatic duct

CiSterna chyli

Axillary lymph nodes

Spleen

Thoracic duct

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lymphatic system T cells are produced in the ___ .and mature in the __ .

liver, thymus

bone marrow, liver

bone marrow, thymus

lymph nodes, thymus


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bone marrow, thymus The thymus is a bilobed lymphoid organ posit ioned in the superior mediastinum in adults, with the inferio r part contained in the anterior med iastinum of child ren; it does not contain lymph nodules or vessels.The main function of the thymus is to potentiat e immunocompetent T cells from t heir immunoincompetent precursors. Addit ionally, self-recognizing T cells are destroyed in the thymus. The thymus is relatively large in newborns, continues to g row until puberty, at which point i t undergoes involution, being replaced by ad ipose t issue. Note: In the adult thymus, t he blood supply is isolated from the parenchyma (which is the functioning portion of the gland as d istinguished from the connective t issue or stroma). This is sometimes referred to as the blood thymus barrier. In the child thymus, the blood supply is not isolated from the parenchyma.

p.~'!" Hassall's corpuscles: are structures found in the medulla of the human thymus, formed from ~~s; eosinophilic type VI epithelial reticular cells arranged concentrically. The function of Hassall's

~j' corpuscles is currently unclear. Digeorge syndrome: is a congenital d isease that is characterized by absent or underdevel-

oped thymus and parathyroid glands. It's typically caused by a deletion on the chromosome numbered 22. Patients suffering from Digeorge have profound immunodeficiency due to a lack ofT cells. No other immune cell populations are affected.

The spleen is formed by ret icular and lymphatic t issue and is the largest lymph organ. The spleen lies between the fundus of the stomach and the d iaphragm. The spleen is purplish in color and varies in size in d ifferent individuals. The spleen is slightly oval in shape with the hilum on the lower medial border. The spleen is entirely covered by peritoneum, except at the hilum. It is enclosed in a fibroelastic capsule that d ips into the organ, forming trabeculae, but trabeculae DO NOT d ivide the spleen into lobes/lobules. The spleen also has no distinct cortex or medulla. The cellular material, consisting of lymphocytes and macro-phages, is called splenic pulp, and i t lies between the trabeculae. Supplied by the splenic artery, a branch of the celiac artery. The spleen is the largest single mass of lymphoid t issue in the body. The spleen can be considered as two organs in one; it filters the blood and removes abnormal cell s (such as old and defective red blood cells), and i t makes d isease -fighting components of the immune system (including antibodies and lymphocytes). The body of the spleen appears red and pulpy, surrounded by a tough capsule. The red pulp consists of blood vessels (splenic sinusoids) interwoven with connective t issue (splenic cord s). The red pulp filters the blood and removes old and defective b lood cells. It, along with the l iver, are site of erythropoiesis (blood formation) in the fetus and infant. The white pulp is inside the red pulp, and consists of little lumps of lymphoid t issue. Antibod ies are made inside the white pulp.

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Pericardium

~-----larynx

'-----Thyroid gland

I leart

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3AI

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lymphatic system Posterior 1/3 of the tongue drains into:

facial nodes

occipital nodes

submandibular nodes

deep cervical nodes

submental nodes

jugulodigastric nodes


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deep cervical nodes The deep cervical lymph nodes are located along the length of the internal jugular vein on each side of the neck, deep to the sternocleidomastoid muscle. The deep cervical nodes extend from the base of the skull to the root of the neck, adjacent to the pharynx, esophagus, and trachea. The deep cervical nodes are further classified as to their relationship to the sternocleidomastoid muscle as being superior or inferior.

The deep cervical lymph nodes are responsible for the drainage of most of the circular chain of nodes, and receive direct efferents from the sa livary and thyroid glands, the posterior 1/3 of the tongue, the tonsils, the nose, the pharynx, and the larynx. All these vessels join together to form the jugular lymph trunk. This vessel drains into either the thoracic duct on the left, the right lymphatic duct on the right, or independently drains into either the internal jugular, subclavian, or brachiocephalic veins. Some regional groups of lymph nodes:

Parotid lymph nodes - receive lymph from a strip of scalp above the parotid salivary gland, from the anterior wall of the external auditory meatus, and from the lateral parts of the eyelids and middle ear. The efferent lymph vessels drain into the deep cervical nodes. Submandibular lymph nodes - located between the submandibular gland and the mand-ible; receive lymph from the front of the scalp, the nose, and adjacent cheek; the upper lip and lower lip (except the center part}; the paranasal sinuses; the maxillary and mandibular teeth (except the mandibular incisors); the anterior two-thirds of the tongue (except the tip); the floor of the mouth and vestibule; and the gingiva. The efferent lymph vessels drain into the deep cervical nodes. Submental lymph nodes -located behind the chin and on the mylohyoid muscle; receive lymph from the tip ofthe tongue, the floor of the mouth beneath the tip of the tongue, the mandibular incisor teeth and associated gingiva, the center part of the lower lip, and the skin over the chin. The efferent lymph vessels drain into the submandibular and deep cervical nodes.

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vein

Lymphatic drainage of face and scalp. A. Superficial drainage. A pericervical collar o f superficial lymph nodes is formed at the j unction of the head and neck by the submental, submandibular, parotid, mastoid, and occipital nodes. These nodes initially receive most of the lymph drainage from the face and scalp. B. Deep drainage. All lymphatic vessels from the head and neck ultimately drain into the deep cervical lymph nodes, either directly from the tissues or indirectly after pass ing through an outlying group o f nodes.

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(Reproduced with pcnniS$ion from Moore KL, Daile)' Af. and Agur AMR. C/inicol/y Oriented AnaJOmy. ed 6. Wolters Kluwer. Ballimore. 20t0.)

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Lymphatic drainage of th e tongue and oral floor. A Left lateral view. B Anterior view.

The lymphatic drainage of the tongue and oral floor is mediated by submental and submandibular groups o f lymph nodes that ultimately drain into the lymph nodes along the internal jugular vein. (A, jugular lymph nodes). Because the lymph nodes receive drainage from both the ipsilateral and contralateral sides (B), tumor cells may become widely disseminated in this region (e.g., metastatic squamous cell carci-noma, especially on the lateral border of the tongue, frequently metastasizes to the opposite side).

4 AI

Reproduced with pe-rmission from Baker E.W. /lead tmd Neck Auatomr.ft,r Den/til Jlfedidt~e. Thieme. New York. 20 I 0.

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lymphatic system When antigen recognition occurs by a lymphocyte, B cells are activated and migrate to which area oft he lymph node?

inner medullary region

medullary cords

medullary sinuses

germinal centers

I refer to card 1-1 for illustration! copyright Cl 20 13-2014 Dental Decks

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germinal centers lymph nodes are small, round specialized dilations of lymphatic tissue that are permeated by lymphatic channels. Their function is primarily to act as filters. They help to remove and destroy antigens that ci rculate in the blood and lymph. For this purpose, lymph nodes contain a lot of macrophages. Lymphoid tissue in the nodes also produces antibodies and stores lymphocytes. Note: The nodes generally occur in clusters along the connecting lymphatic vessels particularly in the armpits, the groin, the lower abdomen, and the sides of the neck. Each lymph node is enclosed in a fibrous capsule with internal trabeculae (connective tissue) supporting lymphoid tissue and lymph sinuses.

The node consists of: Outer (superficial) cortical region: contains separate masses of lymphoid tissue called lymphoid follicles. Primary foll icles are not responding to antigen. They sta in uniformly. Secondary follicles contain predominately B cells (lightly sta ining germinal centers) they are active follicles responding to antigen and are a source of lymphocytes. Paracortical region: is dominated by T cells. B cells enter the node from the blood in this region and quickly migrate to the superficia l cortex. Inner medullary region: lymphoid tissue here is arranged in medullary cords,which are a source of plasma cells (they secrete antibodies). Also contains medullary sinuses.

lymph nodes can be classified as primary or secondary. Lymph from a part icular region drains into a primary node or regional node. Primary nodes, in turn, drain into a secondary node or central node.

Definitions: Germinal centers: are sites within lymph nodes (also within lymph nodules in peripheral lymph t issues) where mature B lymphocytes rapidly proliferate, differentiate, mutate their antibodies (through somatic hypermutation), and class switch their antibodies during a normal immune re-sponse to an infection. Medullary cord is a portion of the medulla of the lymph node which conta ins lymphatic tissue and project into the medullary sinus. B cells and plasma cells are the main cel l types found in the medullary cords.

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lymphatic system The lymph from the lower extremities drains into the:

left internal jugular vein

left subclavian vein

junction of the left internal jugular and subclavian veins

superior vena cava

junction of the right internal jugular and subclavian veins

I refer to card 1 A-I, 2-1 for illustration!


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junction of the left inte rnal jug ular and subclavian veins The thoracic duct is the main duct of the lymphatic system and is located in the posterior mediastinum. It begins below in the abdomen as a dilated sac, the cisterna chyli (at the level of the Tl 2 vertebra) and ascends through the thoracic cavity in front of the spinal column (between the descending thoracic aorta [to its left) and the azygos vein [to its right)). It is the common trunk of all the lymphatic vessels of the body, and drains the lymph from the majority of the body (legs, abdomen, left side of head, left arm, and left thorax). Note: The right lymphatic duct drains much less of the body lymph (only the lymph from the right arm, right thorax, and right side of the head). Important: The thoracic duct is approximately 40 em long and transports lymph from the entire lower half of the body and left upper quadrant. It empties into the left venous angle between the left internal jugular vein and the left subclavian vein (which is actually the beginning of the left brachiocephalic vein). The right lymphatic duct is approximately 1 em long and collects lymph from the right upper quadrant of the body and empties into the right venous angle at the j unction of the right internal jugular vein with the right subclavian vein (which is actually the beginning of the right brachiocephalic vein).

1. The thoracic duct ascends through the aortic opening in the diaphragm, on the right side of the descending aorta. 2. The thoracic duct contains valves and ascends between the aorta and the azygos vein in the thorax. 3. The intercostal lymphatic vessels transport lymph from the left and right intercostal spaces to the thoracic duct. 4. Mammary glands drain lymph into axillary lymph nodes. 5. Kidneys drain lymph into lumbar lymph nodes. 6. Lungs and trachea drain lymph into hilar lymph nodes (which are located in the hilum of the lung).

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lymphatic system Which of the following is NOT a function of the spleen?

removal of old or defective blood cel ls from blood

forming crypts that trap bacteria

storage of blood platelets

storage of iron


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forming crypts that trap bacteria The spleen lies in the left hypochondriac region of the abdominal cavity between the fundus of stomach and the diaphragm. The spleen is an ovoid organ roughly the size of a fist. The spleen contains white and red pulp. The white pulp contains compact masses of lymphocytes surrounding branches of the splenic artery. The red pulp consists of a network of blood-filled sinusoids, along with lymphocytes, macrophages, plasma cells, and monocytes (phagocytic white blood cells). There are three major functions of the spleen, and these are handled by three different tissues within the spleen:

Reticuloendothelial tissue: concerned with phagocytosis of erythrocytes and cell debris from the bloodstream. This same tissue may produce foci of hemopoiesis when RBCs are needed. Venous sinusoids: along with the power of the spleen to contract, provides a method for expelling the conta ined blood to meet increased circulatory demands White pulp: provides lymphocytes and a source of plasma cells and hence antibodies for the cellular and humoral specific immune defenses composed of nodules containing malpighian corpuscles

Blood enters the spleen at the hilum through the splenic artery and is drained by the splenic vein, which joins the superior mesenteric vein to form the hepatic portal vein to the liver. The nerves to the spleen accompany the splenic artery and are derived from the celiac plexus. Note: Like the thymus, the spleen possesses only efferent lymphatic vessels. Remember: Although the spleen does not develop from the primitive gut, as do the lungs, liver, pancreas, gallbladder, stomach, esophagus, and intestines, it shares the blood supply of the foregut which is supplied by the celiac trunk. The spleen develops from mesenchymal cells of the mesentery attached to the primitive stomach.

1. Infectious mononucleosis: is a common, acute, usually self-limited infectious disease caused by the EBV, characterized by fever, membranous pharyngitis, lymph node and splenic enlargement. 2. Asplenia: refers to the absence of normal spleen function and is associated with some serious infection risks, especially encapsulated bacteria such as streptococcus pneumo-niae, haemophilus influenzae and neisseria meningitidis.

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Spleen-Visceral view

Splenic vein

Impression of the colon (left colic flexure)

border

otch In superior border

stomach

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lymphatic system Which of the following tonsil(s) is/are covered by nonkeratinized stratified squamous epithelium? Select all that apply.

lingual tonsils only

pharyngeal tonsil only

palatine tonsils only

pharyngeal and palatine tonsils

lingual and palatine tonsi ls

all of the above


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lingual and palatine tonsils The tonsils are lymphatic organs that l ie under t he su rface l ining of the mouth and throat. They are con-sidered part of the secondary immune system. They si t in the respiratory and alimentary tracts in position to be exposed to inspired or ingested antigens from air or food. When sufficient antigen is p res-ent, this stimulates the 8 cells in the germinal zone of the lymphoid foll icle to d ifferentiate and produce antibodies. The tonsils are involved in the production of mostly secretory lgA, which is transported to the surface, providing local immune protection. There are three sets of tonsils, named accord ing to their position.

The adenoids (pharyngeal tonsil) are located on the posterior wall of the nasopharynx. They are at their peak of development during childhood. They are surrounded partly by connective ti ssue and part ly by ciliated pseudostratified columnar epithelium (respiratory epithelium). They contain no crypts. The palatine tonsils are located on the posterolateral walls of the throat, one on each side. They reach their maximum size during early childhood, but after puberty d iminish considerably in size. These are the tonsils that are noticeably enlarged when a person suffers from a sore throat." They contain many crypts, lymphoid follicles. but no sinuses. The palat ine tonsils are surrounded partly by connective t issue and part ly by nonkeratinized stratified squamous epithelium. Important point:The best way to d istinguish the palatine tonsil from the pharyngeal tonsil on the histolog ic level is the t ype of epithelium associated with it . The lingual tonsils are smaller and more numerous. They are a collection of lymphoid foll icles on the posterior portion of the dorsum of the tongue. Each has a single crypt. They are surrounded by non-keratinized stratified squamous epithelium. Note: The th ree groups of tonsil s are often referred to as Waldeyer's Ring or the Tonsillar Ring.

Remember: Peyer's patches are similar in structure and function to the tonsils (Peyer's patches form "intestinal tonsils"). Located in t he small intestine (specifically, the ileum}, they serve to destroy the abundant bacteria, wh ich would otherwise th rive in the moist environment of the intestine. Note: Peyer's patches and tonsils are considered subepithelial and non-encapsulated lymphoid t issues. Tonsillectomy: is a su rgical procedure in which the tonsils are removed from either side of the tonsillar fossa. The procedure is performed in response to cases of repeated occurrence of acute tonsillit is or ade-noid it is, obstructive sleep apnea, nasal airway obstruction, d iptheria carrier state, snoring, or peri tonsillar abscess. For children. the adenoids are removed at the same time, a procedure called adenoidectomy.

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Inferior surface of tongue

Apex

The anterior free part constituting the majority of the mass of the tongue is the body. 111e posterior at-tached portion is the root. The anterior (two thirds) and posterior (third) parts of the dorsum of the tongue are separated by the terminal sulcus (groove) and foramen cecum. Brackets, indicate parts of the dorsum of the tongue and do not embrace specitic parts.

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Reproduced Ytith llcrmission from Moore KL Oalley Af:. andAgur AMR. (1inico/ly OrimMI A11t11omy. c:d 6. Wolters Kluwer. Baltimore, 2010.

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blood In which of the following locations would one most likely find yellow bone marrow in an adult?

diaphysis offemur

epiphysis of humerus

ribs

crania l bones

vertebrae


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diaphysis offemur

***Yellow marrow is found in the hollow center of the diaphysis (the long shaft of the bone) known as the medullary cavity.

The bones are not solid structures. Cavities in the cranial bones, vertebrae, ribs, ster-num, and the ends of long bones contain red bone marrow. This blood-forming tissue produces erythrocytes, leukocytes, and thrombocytes with in bones by a process called hemopoiesis.

1. Before birth, the formed elements are also produced in a number of other locations, including the yolk sac, liver, spleen, and lymph nodes. 2. Erythropoiesis refers specifically to the production of erythrocytes.

The red bone marrow contains precursor cel ls called hemocytoblasts (multipotent stem cells) that g ive rise to all of the formed elements of the blood. The hemocyto-blasts give rise to various committed progenitor cells, which give rise to the different types of formed elements. For example, the erythrocytes develop from proerythrob-lasts; the platelets develop from large cells cal led megakaryocytes.

When a child is 7 years of age, yellow marrow begins to appear in the distal bones of the limbs. This replacement of marrow gradually moves proximally, so that by the time the person becomes an adult, the red marrow is restricted to the bones of the skull, the vertebral column, the thoracic cage, the girdle bones, and the head ofthe humerus and femur. ***At birth, all bone marrow is red.

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Which of the following cells are agranulocytes? Select all that apply.

basophils

eosinophils

lymphocytes

monocytes

neutrophils

ANATOMIC SCIENCES

blood

10 copyright Cl 20 13-2014 Dental Decks

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lymphocytes monocytes

Formed Avg. No./mm3 Element Description Function

Erythrocytes 5 million Biconcave, anuclcated cell Transport oxygen Platelets 150,000300,000 Small cellular fragments Hcmoslasis LeukOC)'tes 10,000

Granulocytes: Lobed nucleus, fine granules Part of the immune system . Ncutrophils 5,400

(phagocytosis) . Eosinophils 275 Lobed nucleus, red or yellow May phagocytize AbAg

granules complexes (active against parasites) . Basophils 35 Obscure nucleus, light purple Release histamine, heparin, and

granules serotonin Agranulocytes: . Monocytes 540 Kidneyshaped nucleus Phagocytosis, differentiate into tissue

macrophages . Macrophagcs Ruffied membrane, cytoplasm Phagocytosis, secretion of cytokines

with vacuoles and vesicles

. Lymphocytes 2,750 Round nucleus, liulc cytoplasm Produce Abs, destroy specific target cells

***Absolute neutrophil count measures cells per microli ter. A risk of infection increases dramatically w ith a reading of


blood Which of the following statements is NOT true regarding erythrocytes? They:

are biconcave in shape

have an average lifespan of 30 days

rely completely on anaerobic metabolism

have no nucleus

have no mitochondria

are disposed of by the spleen

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have an average lifespan of 30 days The process of erythrocyte production is called erythropoiesis. The hormone that stimulates erythropoiesis is called erythropoietin, which is produced primarily by the kidneys. The average l ife span of a red blood cell is 120 days. Differentiation stages of erythroblast: Hemocytoblast -common myeloid progenitor- unipotent stem cell - proerythroblast- basophilic erythroblast- polychromatophi lic erythroblast -normoblast - reticulocyte- erythrocyte

Erythrocytes, or red blood cells, make up the largest population of blood cell s, numbering from 4.5 million to 6 million per cubic millimeter of blood. Their principal function is to transport oxygen and carbon dioxide. The hemoglobin molecules in erythrocytes combine with oxygen in the lungs to form oxyhemoglobin. The oxygen is transported in this state to the tissues of the body. In the tissues, the oxygen is released to d iffuse into the interstitial fluid. Within the t issues, carbon d ioxide is combined with the hemoglobin molecules to form carbaminohemoglobin, which is transported to the lungs. Note: About 70% of carbon d ioxide, however, is transported by the b lood plasma as bicarbonate ions (HCOj) one of the most important extracel lular buffers. Remember: (1) The proportion of erythrocytes in a sample of blood is called the hematocrit (usually around 46% for males and 40% for females). (2) The precursor cell found in the red bone marrow that gives rise to all of the formed elements of the blood is the hematocytoblast (these are p luripotent stem cell s), which gives rise to various committed multipotent progenitor cells (aka Colony-forming cell s or CFC), which then give rise to the different types of formed elements. Note: Granulocyte Colony-stimulating factor (G-CSF) is the hormone that stimulates precursor cells in the bone marrow to d ifferentiate into white blood cells (leukocytes).

8 1. Sickle cell anemia is an autosomal recessive genetic blood disorder in which the body pro-duces abnormally shaped red blood cell s. The cells are shaped l ike a crescent or sickle. They don't last as long as normal, round red blood cells, which leads to anemia. The sickle cell s also get stuck in blood vessels, blocking blood flow. This can cause pain and organ damage. Mutation is a hy-drophil ic glutamic acid (polar) substitution with a hydrophobic amino acid valine. 2. Genetic deficiency of glucose-6-phosphate-dehydrogenase (G6PD) causes severe hemolytic crisis in affected individuals secondary to decreased NADPH and the inabil ity of RBC's to main-tain membrane integrity. It's induced by sulfa drugs, oxidants and fava beans.

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blood The formed elements of blood include all of the following EXCEPT one. Which one is the EXCEPTION?

plasma

red blood cells

platelets

white blood cells



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plasma

BLOOD LEUKOCYTES FORMED

8% of ELEMENTS body VOLUME (number per cubic mm) Neutrophils

weight 60-70% Plasma Leukocyt es --+ Lymphocytes

4 to 6 liters --+ 55% 5-l 0 thousand 20-30% Monocytes

Temp = For med Platelets 2-6% 38"C Elements - Eosinophils 150-300 thousand

45% 1-4% pH of 7.35 Erythrocytes Basophils

To 7.45 4.3-5.8 million 0-1%

Important: The mnemonic " Never Let Monkeys Eat Bananas" identifies the order of abundance of leukocytes.

Note: The term leukocyte refers to all types of white blood cells as listed above, while the term granulocyte refers only to those containing visible cytoplasmic granules. The granulocytes are the neutrophils, eosinophils and basophils.

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blood Regarding the difference between plasma and serum, which of the following statements is true?

serum is yellow; plasma has no color

serum contains antibodies; plasma does not

plasma contains clotting proteins; serum does not

plasma contains hemoglobin; serum does not



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plasma contains clotting proteins; serum does not

Plasma is approximately 91% water; the other portion is made up of various materials (see chart below). The portion of the blood that is not plasma consists of formed elements, which includes erythrocytes (red blood cells), leukocytes (white blood cel ls), and cell fragments called platelets. Note: Serum= blood plasma without fibrinogen (after coagulation)

BLOOD { Albumins PLASMA 55% 8%of (WEIGHT) Globulins body VOLUME / 38% weight P roteins Fibrinogen Plasma 7% 7%

4 to 6 liters -

55% Water

Temp = Formed 9 1% { Metabolic end products 3sc Elements Food materials 45% Other Solutes Respiratory gases pH of7.35 2.0% Hormones, etc. To 7.45 Ions

Human serum albumin is the most abundant protein in human blood plasma. It is pro-duced in the liver. Albumin constitutes about half of the blood serum protein. It trans-ports hormones, fatty acids, and other compounds, buffers pH, and maintains osmotic pressure.

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Platelets are best described as:

megakaryocytes

cytoplasmic fragments

agranulocytes

immature leukocytes

lymphoid cells

ANATOMIC SCIENCES

blood


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cytoplasmic fragments

*** Although platelets are often classified as blood cells, platelets are actually fragments of large bone marrow cells ca lled megakaryocytes.

Platelets are minute, irregularly shaped, disc-like cytoplasmic bodies found in blood plasma that promote blood clotting and have no definite nucleus, no DNA, and no hemoglobin.

Normal blood contains 150,000 to 300,000 platelets per cubic mm. Their li fe span is 7-10 days; they are removed in the spleen and the liver. Note: Thrombopoietin (a g lycoprotein hormone) is produced by the kidney and liver. Thrombopoietin stimulates precursor cells in the bone marrow to differentiate into megakaryocytes. Megakaryocytes give rise to platelets.

Remember: Platelets stop blood loss by forming a platelet plug. This plug begins to form when platelets are exposed to a rough surface. They contain many secretory vesicles (granules), which contain chemicals that promote clotting. When platelets adhere to collagen, they release ADP and other chemicals from their secretory vesicles. Many of these chemicals, including ADP, induce changes in the platelet surface that cause the surface to become 'sticky: As a result, additional platelets adhere to the original platelets and form a "plug:'

Important: (1) Thromboxane A2 (TXA2), produced by activated platelets, has prothrombotic properties, stimulating activation of new platelets as wel l as increasing platelet aggregation. (2) Prostacyclin (PGI2) decreases platelet aggregation and causes vasodilatation.

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joints Which of the following is CORRECT regarding the articular cartilages? Select all that apply.

they are covered by d isks

most of them are covered by hyaline cartilage

they are covered by perichondrium

they are covered by periosteum

they are vascular



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most of them are covered by hyaline cartilage Synovial joints are freely movable (diarthrodial), with movement limited only by joint surfaces, lig-aments, muscles, or tendons. They are characterized by four features:

1. Articular cartilage -a thin layer of hyaline cartilage that covers the smooth articular bone sur-faces. This layer contains no blood vessels or nerves. Note: The temporomandibular joint con-tains fibrocartilage, not hyaline cart ilage. 2. Joint cavity- small fluid-filled space separating the ends of adjoining bones. 3. Articular (joint) capsule- double-layered; outer layer of fibrous connective tissue that encloses the joint. 4. Synovial membrane - produces synovial fluid. Found on both bursa and articular cartilage.

Note: Most joints of the body are synovial joints. They are classified functionally as diarthroses (means freely movable). In addition to the features above, some synovial joints have articular discs (TMJ and sternoclavicular joint). These discs consist of fibrocartilage. They divide the cavity into two separate cavities. Synovial fluid is a clear, thick fluid secreted by the synovial membrane, which fills the joint capsule and lubricates the articular cartilage at the ends of the articulating bones. Supporting ligaments (capsular, extracapsular, and intracapsular ligaments) maintain the normal position of the bones. Ten percent of synovial joints have a washer-like structure between bone ends called the meniscus. Its purpose is to absorb shock, to stabilize the joint, and to spread synovial fluid. The meniscus is made out of fibrocartilage, but the meniscus also has no blood supply, no nerves, and no lym-phatic channels. Biologically, the meniscus can't heal itself. The knee meniscus is the most famous and most injured meniscus in the body. Note: A bursa is a fluid-sac that is lined with a synovial membrane. The function of a bursa is tore-duce friction. For example, a bursa may be located between a tendon and a bone to reduce the fric-t ion of the tendon passing over the bone when the tendon's muscle contracts. Inflammation of the lining of a bursa is referred to as bursitis.

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Joint cavity

Structure of Synovial Joints 15 1

Reproduc~d wilh permission from Patton KT, Thibodeau GA; Mosby's Hnndbook of Anatomy & Physiology. St. loUJs. 2000. Mosby.

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Which of the following joints is/are a synarthrosis? Select all that apply.

temporomandibular joint

skull sutures

synovial joints

condyloid joints

ANATOMIC SCIENCES

joints


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skull sutures Articulations (joints) are the structures where bones connect. There are three main classes of articulations based on the amount of motion they allow:

1. Synarthrosis - immovable joint (fibrous joint). Sutures found between the flat bones of t he skull are of this type.

Note: Gomphosis is an example of a synarthrosis. It is t he joint that binds t he teeth to the bony sockets (dental alveol i) in the mandible and maxilla.

2. Amphiarthrosis - slightly movable joint (cartilaginous joint). One example is the symphysis pubis, where t he two os coxa bones join anteriorly.

3. Diarthrosis - freely movable joint (synovial joint).

Joints can also be classified based on the type of associated connective tissue: Fibrous (joined by fibrous connective t issue) - two types: sutures (of skull) and syndesmoses (between radius and ulna)

Cartilaginous (joined by fib rocartilage or hyal ine carti lage) - two types: syn-chondroses, which are joined by hyaline cartilage (epiphyseal plates w ithin long bones), and symphyses, which are joined by a plate of fibrocartilage (pubic sym-physis)

Synovial (joint capsule containing a synovial membrane that secretes a synovial f luid)- most joints, such as the temporomandibular joints, are synovial

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joints The spheno-occipital joint and epiphyseal cartilage plates are classified as which of the following joints?

sutures

symphyses

synchondrosis

syndesmoses



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synchondrosis Joints are p laces of union between two or more bones. Joints are classified on the basis of their structural fea-tures into fibrous, cartilaginous, and synovial types.

Fibrous joints (synarthroses): are barely movable or non-movable and are found in these forms: Sutures are connected by fibrous connective t issue and are found between the flat bones of the skull.

Coronal suture: between frontal and parietal bones Sagittal suture: between two parietal bones lambdoid: between parietal and occipital bones Bregma: intersection of coronal and sagittal sutures, it's the site of anterior fontanelle In an infant lambda: intersection of saginal and lambdoid sutures, It's the site of posterior fontanelle in an infant

Syndesmoses are connected by fibrous connective tissue and occur as the Inferior tibiofibular and tympa-nostapedial syndesmoses.

Cartilaginous joints (amphiarthroses): Synchondrosis (primary cartilaginous j oints) are united by hyaline cartilage and permit no movement but growth in the length of the bone. These include epiphyseal cartilage plates and the first rib and sternum. Symphyses (secondary cartilaginous j oints) are joined by a p late of fibrocartilage and are slightly movable joints. These include the pubic symphysis and the intervertebral discs.

Synovial joints (diarthrodial joints): Permit a great degree of free movement. They are characterized by four features: joint (synovial) cavity, ar-ticular cartilage, synovial membrane, and articular capsule. These joints are classified according to axes of movement Into:

Gliding (plane): include those joints found in the carpal bones of the wrist and the tarsal bones of the ankle Hinge: the elbow and knee joints are examples Pivot found between atlas (Cl )and axis (C2)ofthe vertebral column Ellipsoidal (condyloid): found between the distal surfaces of the forearm bones (radius and ulna) and the adjacent carpal bones Saddle: found where the metacarpal of the thumb meets the trapezium of the carpus (wrist) Ball-and-socket (universal): allows almost all types of movements. Examples include the shoulder j oint and the hip joint.

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Ball-and socket joint

Head of femur (ball)

Scaphoid bone

Ellipsoidal (condyloid) joint

~(',.,\-,Radius Y'Y"'

Carpal bones

Ulna

Art icula tions- Ball-and-socket joint, Ellipsoidal joint, Gliding joint 17-1

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Saddle joint

Humrus Hinge Joint

Trochlea (of humerus) process

17AI

Articulations- Hinge joint, Pivot joint, Saddle joint

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joints The paramedics arrive at the scene of a minor motor vehicle collision. One driver claims to have experienced whiplash and is having trouble shaking her head in a "NO" motion. She is fine with nodding her head in a "YES" manner. Which of the following joints allows maximum rotational movement of the head about its vertical axis (saying "NO")?

intervertebral joint

atlantoaxial joint

atlanta-occipital joint

costovertebral joint



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atlantoaxial joint

This joint is the synovial articulation between the inferior art iculating facets of the atlas (first cervical vertebra) and the superior art iculating facets of the axis (second cervical vertebra). The atlas and axis, or Cl and C2, do not have an intervertebral disc nor an intervertebral fo ramen between them. Cl has two lateral masses (no vertebral body) where it makes contact with the occiput and C2. The inferior art icular facets of the Cl and the superior art icular facets of C2 form 2 joints, one on each side. There is also a third joint formed by the dens, or odontoid process, of C2 and the interior of the anterior arch of Cl. This is the joint you use to shake your head as in saying "NO':

Note: The atlanto-occipital joint permits rocking or nodding movements of the head as in saying "YES:' This joint is the synovial articulation between the superior articulating facets of the atlas (first cervical vertebra) and the occipital condyles of the skul l. SAADDES


joints When someone is rotating the forearm with the palm turning outward, this motion is termed as:

abduction

adduction

flexion

extension

pronation

supination



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supination

Movement D esc.ription Exam ples

Flexion Decreasing the inner angle of the Bending the elbow joint Dropping the chin to the chest

Folding forward (flexion of spine) Extension Increasing the inner angle of the joint Back bend

Kicking leg back (hip extension) Abduction Moving away from the midline o f Lifting leg to the side

the body Lifting anns up from sides into T position

Adduction Moving towards the midline of the Crossing one leg in front of the other body Crossing arm in front of torso or behind back

Lateral Flexion Side bending (neck/torso) Dropping ear towards shoulder Crescent Stretch (dropping one hand down same s ide of body)

Rotation Rotating or pivoting around a long Twisting along s pinal column (seated twist) axis Turning palms up and down

Pronation Rotating the foreann with the palm Lifting ann then turning arm (like empty ing a turning inward can o f soda)

Supination Rotating the fore.ann with the palm Lifting ann then turning arm back (tuming turning outward palms towards ceiling)

Evers ion Turning the foot laterally resulting in Standing with the weight on the inner edge o f the sole moving outward the foot

Protraction Draw forward (shoulder) Round shoulders forward "spreading" back

Retraction Draw back (shoulders) Squeezing shoulder blades together

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urinary system The ureter connects which of the following parts of the kidney to the urinary bladder?

renal papi lla

renal columns

renal calyx

renal pelvis



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renal pelvis The kidneys are located at the back of the abdomen, one on each side of the spine, at the level of the lower ribs. They are a pair of reddish, bean-shaped organs that are highly vascularized and perform the following functions of the urinary system: (1) forming urine (2) maintaining homeostasis and (3) hormone secretion (i.e., erythropoietin and renin). The kidneys are located on either side of the lumbar spine. They lie retroperitoneally (external to the peritoneal lining of the abdominal cavity) in front of the muscles attached to the vertebra l column.

Internal features of kidney: Cortex - outer light-brown layer (glomeruli and proximal and distal convoluted tub-ules are located here). Site of blood filtration. Medulla - inner dark-brown layer, contains cone-like structures called renal pyramids that are separated by renal columns. Renal columns - extensions of renal cortex. Renal pelvis - a hollow inner structure that joins with the ureters (the tubes that con-duct urine to the bladder). Receives urine through the calyces. Renal papilla - apex of pyramids, here the collecting ducts pour into minor calyces Renal calyx - extension of the renal pelvis. Minor calyces unite to form major caly-ces, which urine is emptied into.

1. The right kidney lies slightly lower than the left kidney due to the large size of the right lobe of the liver. 2. Each kidney is surrounded by a fibrous renal capsule and is supported by the adipose capsule. 3. Each kidney has an indentation, the hilum, on the medial border, through which the ureters, renal vessels, and nerves enter or leave. 4. Each kidney receives its blood supply from a renal artery, a branch of the abdominal aorta.

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Renal pyramid (medul

Renal column

2().1

Kidney- Coronal view of right kidney

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urinary system Name the following structures of the nephron in the order they are encoun-tered from blood to urine.

(1) distal convoluted tubule (2) bowman's capsule (3) collecting duct (4) g lomerulus (5) loop of Henle (6) proximal convoluted tubule

2,4,6, 1 ,5,3

4,2,6,5, 1,3

6,2,4,5, 1,3

2,6,4,5, 1,3


copynght 0 20 132014 Dental Decks

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4,2,6 ,5, 1,3

The subunit of a kidney that purifies blood and maintains a safe balance of solutes and water is the nephron; it is the functional unit of the human excretory system. About one million nephrons are in the cortex of each kidney, and each one is a long tubule w i th a closed end, called the Bowman's capsule.

Components of the nephron incl ude: Renal corpuscle: which consists of a glomerulus (network of parallel capi llaries) and a double-walled cup, the Bowman's capsule which surrounds the glomerulus and collects filtrate. The renal corpuscle is the site of filtration; this normally prod uces protein-free and cell-free filt rate that passes into the prox-imal convoluted tubules. The tubular portion: has four main regions. Fi lt rate from the Bowman's capsule f irst passes into the proximal convoluted tubule in the cortex. Here, glucose, amino acids, metabolites, and electrolytes are reabsorbed from filtrate and returned to circulation. Next, the filtrate enters t he loop of Henle, first through its descend ing l imb and then through its ascending l imb. Here, the filtrate is concentrated through electrolyte exchange and reabsorption to produce a hyperosmolar fl uid. This loop extends deep into the med ulla. From there. fluid enters the distal convoluted tubule, also in the cortex. Here, sodium is reabsorbed under the influence of aldosterone. From the distal convoluted tubule. filt rate enters the collecting duct, which is the d istal end of the nephron. This is the site of final concentration of filtrate, which then empties into papillary d ucts deep w ithin the med ulla.

After filt ration, fl uid in the t ubulesofthe nephrons undergoes two more processes, both involving the per-i tubular capillaries: tubular reabsorption and tubular secretion. Some blood is not fil tered and passes into the efferent vessels and peritubular capi lla ries. Many substances that are filtered are returned to the per-i tubular capillaries from the tubules by reabsorption, often at high rates (e.g., water, glucose, sod ium). Waste p roducts are retained and emptied into a collecting tubule, which is d ischarged to the ureters.

Macula densa is an area of closely packed specialized cells l ining the wall of the distal tubule. The cells of the macula densa are sensit ive to the concentrat ion of sodium chloride in the d istal convoluted t ubule. A decrease in sod ium chloride concentration ini tiates a signal from the macula densa that has t wo effect s: (1) i t decreases resistance to blood flow in the afferent arterioles, which increases glomerular hydrostat ic pres-sure and helps return glomerulus filtration rate (GFR) toward normal, and (2) it increases renin release from the j uxtaglomerular cells of the afferent and efferent arterioles, which are the major storage sites for renin.

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l==li~==::=-:::-:=::::::.::;::=:;==::i::::O::iiii=~ Tubular and collecting system of the nephron. 'f he first pan of [he tubular system is the proximal lUbule, which is a continuation of Bowman's capsule and ini tially pursues a convoluted course (rhe pmximal convo-lured tubules). remaining close to the glome1ulus from which it arise$.

The proximal mbule the-n straightens and descends co-ward the medulla (pmximal !Uraig/H luhu/es. or the I hick descending limb t?fthe loop of Henle). merging with a thin-walled part of the tubular system (lhiu limb of rite loop of Henle). n lis I'Uns down the co11ex, and rhen in the medulla, toward the papillary tip (descending thin limb). It dten loops back on itself (ascending rhin loop) and re-enters the corcex. 1'he wall then become-S thicker, forming the straight segment of rhe distal rubule {the thick ascending limb of the Mop of Henle or I he diswl !Uraighltubule).

In the cortex, close to the glomeruli. the distal mbule be. comes convolmed (dislfll comoluted 1ubule). and emp. t ies into a collecting n1bule. which in turn empties imo a co11ecting duc( lying within the medullary ray.

The collecting ducts descend imo the medulla whe.e a number converge to produce large.diamere.r ducts in the papillae (papillary ducts r>r ducts t?{Bellini).11lese ducts open into the calyces at the tips of the papillae, the con. centration of the openings producing a sieve .. ! ike surface appearance to the papillary tip (the area cribi'Osa).

Reproduced wilh p~nmssion from Stevens, A. and Lowe J. f1111t1a11 Histol tJfP' ed 3. Ellievier. Philadclplua, 200S.

21-1

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urinary system Which of the following persists as the definitive (permanent) kidney?

pronephos

metanephros

mesonephros

none of the above



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metanephros The urinary system consists of the kidneys, the ureters, the urinary bladder, and the urethra. This system filters the blood and maintains the volume and chemical composition of the blood. The kidneys are paired organs, which contain extensive vascularity and millions of nephrons within the renal cortex and renal medulla. The kidneys fi lter blood and regulate the volume and composition of body fluids during the formation of uri ne.

Note: The development of the kidney proceeds through a series of successive phases, each marked by the development of a more advanced kidney: the pronephros, mesonephros, and metanephros. The pronephros is the most immature form of kidney, while the metanephros is most developed. The metanephros persists as the definitive adult kidney.

The ureters are long, slender, fibromuscular tubes that transport urine from the pelvis of the kidney to the base of the urinary bladder. Because the left kidney is higher than the right, the left ureter is usual ly slightly longer than the right. The ureters are narrowest where they originate, at the renal pelvis (ureteropelvic junction). Note: Filling of the bladder constricts the ureters at the ureterovesical junction, where they enter the bladder. Peristaltic waves, occurring about one to five t imes each minute, move urine through the ureters.

Remember: In the female, the ureter descends posterior to the ovary and into the base broad lig-ament passing under the uterine artery"water under the bridge.

The urinary bladder is a distensible sac that is situated in the pelvic cavity posterior to the symphysis pubis. The urinary bladder is slightly lower in the female than in the male.lt concentrates and serves as a reservoi r for urine, which the bladder receives from the kidneys through the ureters and discharges through the urethra.

Remember: Transitional epithelium is found lining the urinary bladder, and the cells of this tissue are specia lized to change shape in response to pressure. When the bladder is empty, these cells are more or less cuboidal in shape, but as the bladder fills the cells become compressed and flattened.

The urethra is a fibromuscular tube that carries urine from the urinary bladder to the outside of the body. In males, the urethra carries semen as well as urine. Note: The portion of the male urethra that passes through the urogenital diaphragm is called the membranous urethra.

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22-1

Urinary System (m ale)

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foramina A 26-year-old female has been previously diagnosed with McCune-Albright syndrome. There is bony fibrous dysplasia of the anterior cranial base leading to the encasement and narrowing of the optic canal. Although her vision is normal, there is concern that there will be compression of the optic nerve and which of the following other structure(s)?

ophthalmic nerve (CN Vl)

cranial nerves Il l, IV, and VI

ophthalmic ar tery

ophthalmic veins



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ophthalmic artery

The optic canal is located posteriorly in the lesser wing of the sphenoid. It commun-icates w ith the middle cranial fossa. It transmits t he optic nerve and the ophthalmic artery.

Bony Opening Location (Bone) Contents Cribrifonn plate with foramina Ethmoid Olfactory nerves (CN I) Hypoglossal canal Occipital Hypoglossal ner\e (CN XII) Carotid canal Temporal Internal carotid artery

Lacrimal canal Maxilla and lacrimal Nasolacrimal (tem) duct

Inferior orbital fissure Sphenoid and maxilla Infraorbital and zygomatic branches of max-illary nerve (V2), infraorbital artery, and part of inferior ophthalmic vein

Superior orbital fissure Sphenoid Oculomotor (CN I II), trochlear (CN IV), and abducens (VI) nerves; lacrimal, frontal and nasoci liary branches of ophthalmic nerve (VI); superior and inferior divisions of ophthalmic vein; sympathetic fibers from cavernous plexus

Optic canal and foramen Sphenoid bone Optic nerve (CN II) and ophthalmic artery

Stylomastoid foramen Temporal Facial nerve (CN VII)

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Frontal incisure Posterior ethmoidal foramen Anterior ethmoidal foramen

r---+- 7 -- Optic canal

Infraorbital foramen

Right Orbit-Anterior View

Reproduced wilh permi.i>Sion from Shut nke M. Schulte E.. Schumacht'T U; /lead ami Neck At~awmrfm Dental Medid11e: New Yort., 2010. Thieme Medica] Publishers.

Nasal bone

Lacrimal bone

23 1

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foramina A 62-year-old female visits the family physician with complaints of right-sided hearing loss, ringing in the right ear (tinnitus), numbness over the right half of her face, and dizziness. The physician diagnoses her with an acoustic schwannoma that is occluding her right internal acoustic meatus. The internal acoustic meatus pierces the posterior surface of the petrous part of the tem-poral bone. The internal acoustic meatus transmits which two structures?

trigeminal nerve (CN V) and facial nerve (CN VII)

facial nerve (CN VII) and vestibulocochlear nerve (CN VIII)

vestibulocochlear nerve (CN VI II) and vagus nerve (CN X)

trigeminal nerve (CN V) and vagus nerve (CN X)



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facial nerve (CN VII) and vestibulocochlear nerve (CN VIII)

The vestibulocochlear nerve enters the internal acoustic meatus and remains within the temporal bone, to the cochlear duct (hearing}, semicircular ducts, and maculae (balance). The fadal nerve enters the internal acoustic meatus, the facial canal in the temporal bone, and emerges from the stylomastoid foramen. The stylomastoid foramen lies between the styloid and mastoid processes of the temporal bone. Note: The facial nerve, upon entering the internal acoustic meatus also gives rise to the chorda tympani branch (which is responsible for the parasympathetic innervation to the submandibular and sublingual gland). It also provides sensory taste fibers for the anterior 2/3 of the tongue.

After the main trunk of the facial nerve exits from the stylomastoid foramen, it enters into the substance of the parotid gland. It is here that it gives off five main branches that will supply motor innervation to the muscles offacial expression.

Facial nerve branches mnemonic: "The Zebra Bi t My Cow"- From superior to inferior:

Temporal branch Zygomatic branch Buccal branch Mandibular branch Cervical branch

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foramina Which of the following foramina appears as a small round radiolucent area on the mandibular premolar and can be confused with a periapical abscess if not recognized correctly?

mandibular foramen

incisive foramen

mental foramen

foramen ovale



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mental foramen

The mandibular foramen is located on the medial surface of the ramus of the mandible just below the lingula, midway between the anterior and posterior borders of the ramus. The foramen leads into the mandibular canal, which opens on the lateral surface of the body of the mandible at the mental foramen. Important: In relationship to the occlusal plane of the mandibular molars, the mandibular foramen is located at or slightly above the occlusal plane and posterior to the molars.

Note: The lingula is a tongue-shaped projection of bone that serves as the attachment for the sphenomandibular ligament.

Remember: The inferior alveolar nerve (branch of V3), artery, and vein travel through the mandibular foramen. At the mental foramen, the inferior alveolar nerve ends by dividing into (1) the mental nerve, which exits the mental foramen and supplies the skin of the mental region, mucous membrane and attached gingiva of the ipsilateral mandibular anterior and premolar teeth and (2) the incisive branch which continues coursing through the mandible and supplies the pulp chambers of the anterior teeth and adjacent mucous membrane.

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Reproduced with pcnnis~ion from Shue.nke M, Schult~ E. Schumach~r U; Nt!tul and Net:k An11tmny fi'r Dental Mt!dicint!; N~w York. 20 I 0. Thiem~ Medic.al Publ i..o:h~rS.

Mental

Mandibular notch Head of

condyle

11 -"o::::J--- Pterygoid fovea

Mental Body of Oblique foramen mandible line

Ramus of mandible

Oblique left lateral view of the mandible. This view displays the coronoid process, the condylar process, and the mandibular notch between them. The coronoid process is a site for muscular attach-ments, and the condylar process bears the head o f the mandible, which a1ticulates with the a1ticular disc in the mandibular fossa o f the temporal bone. 2s-1

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foramina Through which ofthe following foramina does the largest ofthe three (paired) arteries that supplies the meninges pass?

foramen magnum

jugular foramen

foramen rotundum

foramen ovale

foramen spinosum

foramen lace rum


copynght 0 20 132014 Dental Decks

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foramen spinosum- the artery i s the middle meningeal artery which i s the largest of the three (paired) arteries which supply the meninges, the others being the anterior meningeal artery and the posterior meningeal artery

The jugular foramen lies between the lower border of the petrous part of the temporal bone and the condylar part of the occipital bone. The jugular foramen transmits the following structures: inferior petrosal sinus, sigmoid sinus (becoming the internal jugular vein), the posterior meningeal arterty (at th is point, still called the ascending pharyngeal artery) and the glossopharyngeal, vagus, and accessory nerves.

Bony Opening

Foramen rotundum

Foramen ovalc

Foramen magnum

Foramen spinosum

Mental foramen

Location (Bone)

Sphenoid

Sphenoid

Occipital

Sphenoid

Mandible

Greater palatine for.smcn Palatine

Lesser palatine foramen Palatine

Incisive fOramen Maxilla

Jugular fOramen Occipital and temporal

Contents

Maxillary nerve (V-2) Mandibular nerve (V-3) Spinal cord, vertebral arteries, and "spinal rootsH of the

acccs.~ory nerve

Middle meningeal artery

Mental nerve, artery and vein

Greater palatine nerve, artery, and vein

Lesser palatine nerve, artery, and vein

Nasopalatine nerve and branches of the sphenopalatine artery

Inferior petrosal sinus, sigmoid sinus (becoming the internal jugular vein), posterior meningeal artery, and glossopharyngeal, vagus and acccs.;;ory nerves

Remember: The accessory nerve (CN XI) enters the cranial cavity through the foramen mag-num, where it immediately joins with the vagus nerve (CN X) and subsequently exits the cran ial cavity through the jugular foramen.

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Palatine bone Greater palatine

foramen Lesser palatine

foramen Infratemporal crest -

Scaphoid fossa Sphenoidal foramen

Foramen ovale Foramen splnosum -

Foramen laeerum --Petrotympanic fissure

Carotid canal Jugular foramen

Stylomastoid foramen

Hypoglossal canal

Foramen magnum

Inferior nuchal line~

Superior nuchal line

Supreme nuchal line The basal aspect of the skull

Incisive foramen

Choana Zygomatic bone, temporal surface Inferior orbital fissure Zygomatic arch Hamulus Pharyngeal canal Vomerovaglnal canal Pharyngeal tubercle Mandibular fossa

Occipital condyle Mastoid process Mastoid Incisure Condylar canal Mastoid foramen

._.1"'---EO>


Chiasmatic groove

Optic canal

Anterior clinoid process

Foramen ovate

Foramen spinosum

Arterial groove

Clivus PetrCKH:e:ipital

fissure Hypoglossal canal

Groove for sigmoid sinus

Ethmoid bone, cribrifonn plate

lnlerior of I be base of I be skull

Frontal Frontal crest sinus

Ethmoid bono. crista galll

Frontal bone

Sphenoid bone. lesser wing

Sphenoid bone, greater wing Sphenoid bone, hypophyseal fossa Posterior clinoid process Temporal bone, petrous part Internal acoustic meatus Jugular foramen Foramen magnum

Cerebellar fossa lntomal occipital c rest

Internal occipital protuberance

Cerebral fosaa

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foramina The cranial nerves that supply motor innervations to the muscles that move the eyeball all enter the orbit through a foramen that is between the:

lesser wing of sphenoid and fronta l bone

lesser wing of sphenoid and ethmoid bone

greater and lesser w ings of sphenoid bone

lesser wing of sphenoid, frontal and ethmoid bones



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greater and lesser wings of sphenoid bone

The superior orbital fissure is located posteriorly between the greater and lesser wings of the sphenoid bone. The superior orbital fissure communicates with the middle cranial fossa. It transmits the: superior and inferior divisions of the oculomotor nerve (CN Ill)

trochlear nerve (CN IV) lacrimal, frontal, and nasociliary branches of the ophthalmic nerve (CN Vl) abducent nerve (CN VI) superior and inferior d ivisions of the ophthalmic vein sympathetic fibers from the cavernous plexus

Bony Opening Location (Bone) Contents Mandibular foramen Mandible Inferior alveolar nerve, artery, and vein

Petrotympanic Temporal Chorda tympani nerve fissure

Foramen lacerum Sphenoid, occipital, Nerve of pterygoid canal (greater and deep and temporal petrosal nerves), and artery of pterygoid canal

Supraorbital foramen Frontal Supraorbital nerve. artery. and vein and canal

Infraorbital foramen Sphenoid and maxilla Jnfr.sorbital nerve, artery, and vein and canal

Pterygoid canal Sphenoid Area nerves and vessels

lntemal acoustic Temporal Facial and vestibulocochlear nerves meatus

Extemal acoustic Temporal Opening to tympanic cavity meatus

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Plerlon Coronal suture Frontal bone Squamous suture

Sphenoparietal suture

Sphenofrontal suture Sphenosquamous

suture Supraorbital

foramen Sphenoid bone, greater wing

Ethmoid bone

Nasal bone

Anterior nasal spine

Maxilla

Mandible

protuberance Mental foramen

Lateral 'iew of tbe skuU

glenoid tubercle

Zygomatic Zygomatic arch bone

External acoustic meatus

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respiratory system Which of the following terms means air in the chest?

hemothorax

pyothorax

pneumothorax

pulmothorax

pulmonary inflation



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pneumothorax A penetration wound of the chest wall can lead to a pneumothorax (air in the pleural cavity) or a hemothorax (blood in the pleural cavity).ln both of these situations, the surface tension that binds the lungs to the chest wall is eliminated, and the lung will instantly shrink to the size of a tennis ball.

The lungs fill the pleural divisions of the thoracic cavity; they extend from the root of the neck to the diaphragm. The lungs are the main component of the respiratory system; they distribute air and exchange gases. The right and left lungs are separated by the mediastinum, which contains the heart, blood vessels, and other midline structures; fissures divide each lung into Jobes. Each primary bronchus enters its respective lung at the hilus, an indentation on the mediastinal surface. The bronchi and pulmonary blood vessels are bound together by connective tissue to form the root of the lung. The base, the inferior surface of the lung, rests on the diaphragm. The apex, the most superior portion of the lung, projects above the clavicle. Right lung:

Has three Jobes (superior, middle, and inferior) and three secondary (lobar) bronchi Contains ten bronchial segments (corresponding to the tertiary bronchi) Usually receives one bronchial artery Has a slightly larger capacity than the left lung The azygos vein leaves an impression on the right lung as the vein arches over the root

Left lung: Has two Jobes (superior and inferior) and two secondary (lobar) bronchi Contains eight bronchial segments (corresponding to the tertiary bronchi) Contains a cardiac notch (on its superior lobe), which is an indentation providing room for the heart Usually receives two bronchial arteries Contains a lingula, which is a tongue-shaped portion of its superior lobe that corresponds to the middle lobe of the right lung

Each lung is enclosed in a double-layered pleural sac. One layer is called the visceral pleura; the other is called the parietal pleura. Between the two layers is the pleural cavity, which is filled with serous fluid.

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fissure ..._ __ L_~_Cardlac Middle ._~--...::c~

notch lobe Inferior

lobe

Right lung (B) L~tcrat views

Inferior lobe

Cardiac notch

281

Costal surfaces of lungs. The lungs arc shown in isolation in antcrior(A) and lateral views (B), demon-strating lobes and fissures. C. The heart and lungs are shown in situ. Reproduced with permission from 1\>loorc KL. Dalley AF. and Agur AMR. Clinit


respiratory system The ridge that marks the bifurcation of the trachea into the right and left pri-mary bronchi is the:

carina

lingula

mediastinum

bronchial t ree



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carina

The trachea connects the upper respiratory tract to the lower respiratory tract. It is about 9-1 5 em in length. It is located in front of the esophagus and behind the thyroid g land in the neck. It is considered to be in the superior and middle mediastinum. It is made up of 16-20 incomplete hyaline carti laginous rings that are open posteriorly. The trachea bifurcates into the right and left main stem bronchi at a location called the carina, which is located at the level ofthe sternal angle (T4-T5). A series of ( -shaped rings of hyaline car-tilage strengthen the trachea and prevent i t from collapsing during inspiration. The trachea is lined with ciliated pseudostratified columnar epithelium and mucous-secreting goblet cells, which trap inhaled debris. Ciliary action moves debris toward the oropharynx for removal by coughing.

The trachea branches off into two main bronchi, the left and right p rimary bronchi, which lead to the left and right lung respectively. The right lung is larger and heavier than the left, but it is shorter and wider because the right dome of the d iaphragm is higher and the heart and pericardium bulge more to the left . The right and left mainstem bronchi branch from the trachea at different angles, the right more vertical and more di rectly in l ine with the trachea, thus the right b ronchus is more likely to receive aspi rated material. At this point in breathing, the air has been moistened, puri fied and warmed. Each bronchi enters i ts lung and begins on a series of branches, called the bronchial or respiratory tree. The first of these b ranches is the lobar (secondary) b ranch. On the left, there are two lobar branches, while on the right, there are three. Each lobar branches into one lobe. The next branch is called the segmental (tertiary) b ranch. Each b ranch continues to branch into smaller and smaller b ronchioles. The f inal branch is called the terminal bronchioles. These bronchio les are smaller than 0.5 mm in diameter. Each of these terminal b ronchioles gives rise to several respiratory bronchioles. Note: The first few levels of bronchi are supported by rings of cartilage. Branches after that are supported by irregularly shaped d iscs of cart ilage, while the latest levels of the tree have no support whatsoever.

Note: The right main bronchus divides into three lobar bronchi, and the left main bronchus divides into two lobar bronchi. Each secondary or lobar bronchus serves one of the five lobes of the t wo lungs.

Each respiratory bronchiole subd ivides into several alveolar ducts, which end in clusters of small, thin-walled air spaces called alveoli. These cl usters of alveoli are called alveolar sacs and form the functional unit of the lung.

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primary bronchus

Bronchi in situ -Anterior view 291

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respiratory system Which of the following components of the respiratory system does NOT have cilia?

tertiary bronchioles

primary bronchioles

alveolar ducts

respiratory bronchioles

terminal bronchioles



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alveolar ducts Conducting bronchioles are smaller extensions of bronchi (little bronchi). Those devoid of alveoli in their walls are nearer the hilum of the lung. These conducting passageways deliver air to passageways that have alveoli. The last generations of conducting bronchio les are called terminal bronchioles.

Respiratory bronchioles, continuing from terminal bronchioles, branch nearer to the alveolar ducts and sacs and have occasional alveoli in their wall s. These bronchio les capable of respiring are the first generation of passageways of the respiratory portion of the bronchial tree.

Remember: The conducting zone of the respiratory system is made up of the nose, pharynx, lar-ynx, t rachea, bronchi, bronch ioles, and terminal bronchioles; their function is to filter, warm, and moisten air and conduct it into the lungs. It's also called the dead zone be-cause there is no 0 2 exchange happens here. The respiratory zone is the site of oxygen and carbon dioxide gas exchange, and is composed of the respiratory bronchioles, alveolar ducts, and alveoli.

Bronchioles are characterized by: A diameter of one millimeter or less An epithelium that progresses from ciliated pseudostratified columnar to simple cuboidal (respiratory bronchioles) Small bronchioles have non-ciliated bronchiolar epithelial cells (Clara cells) that secrete a surface-active lipoprotein Walls devoid of glands in the underlying connective t issue Woven bundles of smooth muscle to regu late the bronchiolar diameter Walls devoid of cartilage (small diameter prevents them from collapsing at end of expiration)

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(A) (B)

The Trachea, Bronchi, Bronchioles, and Alveoli (A) The trachea and bronchi (B) The termination of bronchioles into alveoli

30-1

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respiratory system Which of the following vessels supply blood to the bronchi?

pulmonary arteries

pulmonary veins

subclavian arteries

none of the above

I refer to card 29-1, 30-1 for illustration!



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none of the above- the bronchial arteries supply blood to the bronchi Each lung is shaped l ike a cone. It has a blunt apex, a concave base (that sits on the diaphragm), a convex costal surface, and a concave mediastinal surface. At the middle of the mediastinal surface, the hilum is located, which is a depression in which the bronchi, vessels, and nerves that form the root enter and leave the lung.

The root of the lung contains the following structures: Primary bronchus: the right and left bronchi arise from the trachea and carry air to the hilum of the lung during inspiration and carry ai r from the lung during expi ration A pulmonary artery: enters the hilum of each lung carrying oxygen-poor blood Pulmonary vein(s): a superior and inferior pair for each lung leave the hilum carrying oxygen-rich b lood

1. The small bronchial arteries (which are branches of the thoracic portion of the descending aorta) also enter the hilum of each lung and deliver oxygen-rich blood to the t issues. The bronchial arteries tend to follow the bronchial tree to the respiratory bronchioles where the bronchial arteries anastomose with the pulmonary vessels. 2. Branches of the vagus nerve pass behind the root of each lung to form the posterior pul-monary plexus.

Innervation of the lung: The lung is innervated by parasympathetic nerves via the vagus and sympathetic nerves derived from the second to fourth thoracic sympathetic ganglia. These nerves form plexuses around the hilus of the lung and give rise to intrapulmonary nerves accompanying the bronchial tree and blood vessels. Both sympathetic and parasympathetic nerves to the lung contain efferent and afferent fibers.

Important: When foreign objects are aspirated into the trachea, they usually pass into the right primary bronchus because it is larger, straighter, and shorter than the left. It is also in a more di rect line wi th the tra-chea (important in a dental cha ir because if a patient swallows an object it tends to lodge in the right bronchus). Tuberculosis seems to be more common in the right lung than the left due to the shorter right bronchus. The reason that the disease is usually restricted to the apex of the lungs is due to the fact that venti la-tion/ perfusion ratio is high as the blood flow is reduced leading to higher alveolar P02 this provides a bet-ter environment for the obligate aerobes to g row.

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respiratory system Which of the following is NOT a part of the lower respiratory tract?

laryngopharynx

trachea

primary bronchus

alveolar duct



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laryngopharynx

The mediastinum lies between the right and left pleura in and near the median sagittal plane of the chest. It extends from the sternum in front to the vertebral column behind, and contains all the tho-racic viscera except the lungs. It may be divided for purposes of description into two parts:

An upper portion, above the upper level of the pericardium, which is named the superior me-diastinum A lower portion (inferior mediastinum) which is subdivided into three parts:

- that in front of the pericardium, the anterior mediastinum -that containing the pericardium and its contents, the middle mediastinum -and that behind the pericardium, the posterior mediastinum

The respiratory system consists of the upper and lower respiratory tracts, the lungs, and the thoracic cage. The respiratory system is designed to exchange the carbon dioxide accumulated in the blood for oxygen in the airways, which enters the lungs as air from the surrounding atmosphere.

Blood travels continuously through two different circulations: the pulmonary and the systemic cir-cu lations. The heart pumps deoxygenated blood from the veins of the systemic circulation into the arteries of the pulmonary circulation. This blood is oxygenated by the lungs, and then flows back to the heart to be pumped into the arteries of the systemic circu lation.

The structures of the upper respiratory tract include the nose, mouth, nasopharynx, oropharynx, laryngopharynx, and larynx. Besides warming and humidifying inhaled air, these structures provide for taste, smell, and the chewing and swallowing of food.

The lower respiratory tract structures are the trachea, bronchi, and lungs. Bronchi branch into bron-chioles, which in turn branch into lobules. The lobule includes the terminal bronchioles and alveoli. A mucous membrane containing hair-like cilia lines the lower tract. Functionally, the lower tract is subdivided into conducting airways (the trachea and the primary, lobar, and segmental bronchi) and alveoli, the sites of gas exchange.

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primary bronchus

Diaphragm

Respiratory System 321

Reproduced with perm1ssion from BaJTons Ant11omy fo1:bh Card.;;:. Australia. 2009. Global Book l'ublshing.

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respiratory system All of the paranasal sinuses drain into one of the three meatuses (superior, middle, and inferior) EXCEPT one. Which one is the EXCEPTION?

maxillary sinus

frontal sinus

ethmoidal sinus

sphenoidal sinus



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sphenoidal sinus- which drains into sphenoethmoidal recess

Air enters through the nostrils (external nares) that lead to the vestibules of the nose. The bony roof of the nasal cavity is formed by the cribriform plate ofthe ethmoid bone. The lateral walls have bony projections cal led conchae (superior, middle, and inferior), which are also referred to as the nasal turbinates. These conchae form shelves that have spaces (or grooves) beneath them cal led meatuses (superior, middle, and inferior). All of the paired paranasal sinuses drain into the nasal cavity by way of these meatuses except for the sphenoidal sinus which drains into the sphenoethmoidal recess. The na-solacrimal duct, which d rains tears from the surface of the eyes, also empties into the nasal cavity by way of the inferior meatus. The f loor is formed by the hard palate. The nasal cavity opens posteriorly into the nasopharynx via funnel-like openings called the choanae (posterior nares). The maxillary sinus drains into the middle meatus through the semilunar hiatus.

1. The vestibules are lined w ith nonkeratinized stratified squamous ep-ithelium. 2. The conchae of the nasal fossae are lined with pseudostratified ciliated columnar epithel ium. 3. The olfactory epithelium is very prominent in the upper medial portion of the nasal cavity. Both olfactory and respiratory epithelium are characterized as pseudostratified columnar epithel ium; olfactory epithelium is unique in that it contains olfactory sensory cells. 4. The nasal cavity receives sensory innervation from the olfactory nerve fo r smell and from the trigeminal nerve for other sensations. The nasal cavity's blood supply is from branches of the ophthalmic and maxillary arteries.

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Inferior nasal meatus

Lateral Wall of Nose

Reproduced with pcnmssion from Atlll.1 ojH11man AlllJtiJmy: Springhouse:. 2001. Springhouse.

Nasal vestibule

33 1

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respiratory system While ascending to 30,000 feet, the passengers on a commercial flight expe-rience the sensation of their ears "popping:' The swallowing or yawning that triggers this equalizes the pressure of the middle ear with the surrounding atmosphere via the eustachian (auditory) tube. The pharyngeal opening for this tube, along with the salpingopharyngeal fold, pharyngeal recess, and pharyngeal tonsils (adenoids) are all located in the:

laryngopharynx

oropharynx

nasopharynx

none of the above



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nasopharynx

The pharynx (the throat) is a tube that serves as a passageway for the respiratory and di-gestive tracts. It extends from the mouth and nasal cavities to the larynx and esophagus. The pharynx is divided into thre

(dd13-14) anatomic sciences

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