c hapter 22 i nternal t ransport pgs 678-710. 22a t he c irculatory s ystem pgs 678-698

CHAPTER 22INTERNAL TRANSPORTPgs 678-710

22ATHE CIRCULATORY SYSTEMPgs 678-698

22A-1THE BLOODPgs 679-686

THE BLOOD

Blood transports: oxygen, nutrients, and hormones to all body

cells carbon dioxide to the lungs waste molecules to the kidneys.

5 L of blood for healthy adults.

Some cells are red, while others are clear

THE BLOOD

When centrifuged, blood separates into two distinct layers that are separated by a thin third layer.

The upper layer is plasma.

The bottom layer is RBCs

The thin center layer is called the buffy coat and is composed of platelets and WBCs

THE BLOOD

90% water 10% protein, dissolved gases, minerals,

nutrients, hormones, and waste products.

The composition varies depending on diet and health status.

THE BLOOD

FORMED BLOOD COMPONENTS

Cellular components are 45% of the total blood volume including RBCs, WBCs, and platelets.

All originate from a single type of stem cell, the hemocytoblast.

Hemocytoblasts are located in the bone marrow and respond to certain growth factors.

FORMED BLOOD COMPONENTS

ERYTHROCYTES (RBCS)

Early in their life cycle they contain a nucleus with very little hemoglobin.

As they mature, the nucleus is extruded and the amount of hemoglobin increases. At this point the structure is no longer a true cell.

No mitosis and few cellular structures.

Biconcave shape

ERYTHROCYTES (RBCS)

ERYTHROCYTES (RBCS)

Unable to move by themselves, but are carried by the current of blood flow.

Oxyhemoglobin is brighter than normal hemoglobin.

Average life span of an erythrocyte is 90-120 days. Specialized cells in the liver and spleen break down old erythrocytes.

LEUKOCYTES (WBCS)

No hemoglobin

Twice the size of Erythrocytes.

No definite shape

They have nuclei throughout entire life span.

Can move independently

LEUKOCYTES (WBCS)

Various types of leukocytes.

In a healthy person the ratio of leukocytes to erythrocytes is about 1:600

If the first leukocytes to arrive at a site of infection are not successful in stopping the infection, the invading organisms are free to multiply and injury the body’s cells

LEUKOCYTES (WBCS)

Chemicals released from the injured cells initiate an inflammatory response.

This results in additional leukocytes moving out of the blood vessels to engulf and digest or to kill the harmful invaders. Leukocytes also digest and remove injured and dead body cells.

LEUKOCYTES (WBCS)

The accumulation of dead leukocytes, dead organisms, and broken cells forms a thick fluid called pus.

LEUKOCYTES (WBCS)

PLATELETS & BLOOD CLOTTING

Platelets (thrombocytes) develop from large cells called megakaryocytes, which are derived from the hemocytoblasts in the red bone marrow.

No nucleus

Half the size or a red blood cell.

Injured tissue releases a chemical that causes the platelets to stick to the broken edges of blood vessels.


The platelets then release serotonin which causes the smooth muscles of the vessel walls to contract.

Platelets also play an important role in coagulation, the formation of a blood clot.

Coagulation occurs as a result of complex biochemical pathways that involve multiple inter-dependent reactions, enzymes, and coenzymes.


As platelets stick to the rough edges of damaged tissue, they release a substance that aids in the formation of thromboplastin

The formation of thromboplastin triggers the reaction converting the protein prothrombin into thrombin.

Thrombin is used to change fibrinogen into insoluble threads of fibrin.


The fibrin threads form a microscopic meshwork that entangles the blood cells to form a blood clot.

Chemicals in the blood gradually dissolve clots as the vessel wall heals.

An abnormal clot that forms within a blood vessel is called a thrombus.


A thrombus readily forms where the blood flows slowly or where the lining of the blood vessel in narrow and rough, as in the disease atherosclerosis.

If the thrombus or a portion of it becomes dislodged and floats in the blood vessels, it is known as an embolus.

BLOOD TYPES

Determined by the presence or absence of protein or carbohydrate molecules in the membranes of the erythrocytes.

These molecules are called “antigens”.

Antigens stimulate the formation of antibodies that cause blood to clump.

ABO BLOOD GROUP

The presence or absence of two antigens, A and B, in the membranes of the erythrocytes determines the ABO blood type.

Antigen A = Blood type A Antigen B = Blood type B Antigen A & B = Blood type AB No A or B Antigen = Blood type O

ABO BLOOD GROUP

In addition to antigens, three of these blood types also have antibodies.

Type A: produces anti-B antibodies Type B: produces anti-A antibodies Type AB: produces neither antibody Type O: produces both anti-A and anti-B

antibodies

ABO BLOOD GROUP

If type A blood is accidentally given to a person who has type B blood, the person’s body will immediately recognize that the A antigen is a foreign substance, and the anti-A antibodies will quickly attack the A antigens.

This causes the donor’s erythrocytes to agglutinate. Leading ultimately to death.

THE RH SYSTEM

Named after the rhesus monkey from which the antigen was first isolated.

Involves the presence or absence of an antigen in the erythrocyte membrane.

85% of Americans are Rh(+)

THE RH SYSTEM

Normally, human blood plasma does not contain anti-Rh antibodies, but these antibodies can be stimulated into production in an Rh- person.

During pregnancy, if the fetus is Rh+ and the mother is Rh-, the mothers body forms anti Rh antibodies.

THE RH SYSTEM

The antibodies remain in her blood plasma but pose no danger until she becomes pregnant with another Rh+ baby.

This can lead to death of the fetus.

BLOOD TYPES

22A-2THE HEARTPgs 686-691

THE HEART

4 chambered pump

Size of a clenched fist with a weight of 340 g

Approx. 100,800 beats per day.

Every heard beat pushes about 80 ml (2.4 oz) of blood or 8000 L (2100 gal) per day.

8000 L BARREL

STRUCTURE OF THE HEART

Covered by the pericardium which is a loose cover that prevents rubbing against the lungs and inner chest wall.

The pericardial sac is filled with pericardial fluid which reduces friction between the heart and surrounding structures.


Epicardium: outermost layer composed of connective tissue.

Keeps the heart muscle from becoming saturated with pericardial fluid.

Myocardium: thickest portion. Muscle layer that pumps the

blood.

Endocardium: innermost lining of the heart. Prevents blood

from saturating the myocardium.


Septum: A muscular wall that separates the left and right

portions of the heart.

Atria: upper chambers. Atrial myocardium is thin

because these chambers primarily receive blood.

Ventricles: lower chambers. Thicker because they have the

responsibility of pushing blood into the blood vessels of the body.


Atrioventicualar valves: Separates the atria from the ventricles. Right AV valve is the tricuspid valve Left AV valve is the bicuspid valve.

Semilunar valves: located at exits of ventricles.

BLOOD FLOW THROUGH THE HEART

Superior vena cava: drains body parts above the heart.

Inferior vena cava: drains body parts below the heart.

Both empty into the right atrium.


As the right atrium fills with blood, it contracts squeezing the blood through the tricuspid valve and into the right ventricle.

When right ventricle contracts, the tricuspid is forced shut, and the pulmonary semilunar valve opens to allow flow to pulmonary artery.


Each of the two main branches of the pulmonary artery leads to a lung. As blood flows through the capillaries surrounding the alveoli, oxygen is added to the hemoglobin of the blood.

Richly oxygenated blood returns to the left atrium through the pulmonary veins.


The left atrium then contracts, squeezing the blood through the bicuspid valve and filling the left ventricle.

As the left ventricle contracts, the bicuspid valve shuts with considerable force, and blood rushes through the aortic semilunar valve into the aorta.

THE CARDIAC CYCLE

Cardiac Cycle = heartbeat

The contraction of the heart muscle is known as systole.

The relaxing and filling of the heart with blood is called diastole.

THE CARDIAC CYCLE

SA node: starts each systole and thus sets the pace of the heart. The SA node rate can be increased or decreased by input from the nervous system.

The SA node is located in the right atrium near the entrance of the superior vena cava.

THE CARDIAC CYCLE

The electrical impulse from the SA node is transmitted through muscle tissue to both atria, causing them to contract together.

About 0.1 second later, the impulse reaches the AV node, where there is a brief pause to allow for proper emptying of the atria.

THE CARDIAC CYCLE

When the AV node “fires”, it sends an electrical impulse down the bundle of His to the wall of each ventricle.

The fibers of the ventricle walls contract together and efficiently push the blood into the pulmonary artery and the aorta.

THE CARDIAC CYCLE

THE HEART RATE

The typical resting heart rate of an adult is 70 bpm.

During moderate exercise is shoots up to 120 bpm.

If the heartbeat is more than 140 bpm, ventricular diastole may be too short to fill.

22A-3BLOOD VESSELS AND CIRCULATIONPgs 691-695

BLOOD VESSELS

Heart and blood vessels form a closed system.

Arteries carry blood away from the heart.

Veins carry blood toward the heart

Capillaries connect the two

BLOOD VESSELS

Arteries are typically found in deeper tissues.

Almost every cell in the body is near a blood capillary.

Strong walls of arteries have three layers: Outer elastic layer Middle muscular layer Inner epithelial layer

BLOOD VESSELS

BLOOD VESSELS

Arteries form smaller vessels known as arterioles, which in turn branch into microscopic capillaries whose walls are only one cell thick.

The capillaries are the functional units of the circulatory system. Only through these vessels can diffusion of materials occur.

BLOOD VESSELS

BLOOD VESSELS

Next, capillaries merge to form venules which join with other venules to form veins.

Veins have the same three layers as arteries, just thinner. Many veins also contain semilunar valves to prevent reverse blood flow.

BLOOD VESSELS

All veins, except the cardiac and pulmonary, drain blood into the superior and inferior venae cavae. The cardiac veins open directly into the right atrium, and the pulmonary veins return oxygenated blood from the lungs to the left atrium.

PULMONARY CIRCULATION

The pulmonary circulation carries oxygen poor blood from the right ventricle to the lungs.

At any moment about 0.5 L of blood is in the pulmonary circulation.

Requires only a few seconds.

PULMONARY CIRCULATION

SYSTEMIC CIRCULATION

The systemic circulation consists of the flow of blood from the left ventricle to all parts of the body (except the lungs) and then back to the right atrium.

CORONARY CIRCULATION

The coronary circulation carries blood into and out of the heart muscle.

Two coronary arteries that branch off the aorta just distal to the aortic semilunar valve deliver nutrients and oxygen to the myocardium.


The flow of blood in the capillaries of the myocardium nearly stops each time the heart contracts.

The contracted cardiac muscle fibers compress the adjacent coronary vessels as they contract.

RENAL CIRCULATION

The circulation of blood in and out of the kidneys is known as the renal circulation.

As the blood flows through the kidneys, the waste materials are removed for excretion as urine. The blood that leaves the kidneys in the renal veins is the cleanest blood in the body.

PORTAL CIRCULATION

The blood from the digestive organs is carried to the liver by the hepatic portal vein.

The liver also receives oxygenated blood from the hepatic artery.

These vessels branch as they enter liver and blood mixes in the liver sinusoids.

PORTAL CIRCULATION

This flow of blood to the liver is called the portal circulation.

The liver cells remove toxic substances from the blood and metabolize foods.

Blood leaves the liver through the hepatic veins that merge with the inferior vena cava.

PORTAL CIRCULATION

Blood in the portal vein also contains insulin that stimulates excess glucose molecules to form glycogen.

This glycogen can be changed back into glucose when needed, especially between meals.

22A HOMEWORK