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© Endeavour College of Natural Health endeavour.edu.au

BIOH122Human Biological Science 2

Session 10

Respiratory System 1 –

Anatomy & Physiology

Bioscience Department

© Endeavour College of Natural Health endeavour.edu.au 3

Session plan

o Functions of the respiratory system

o Respiratory System Anatomy:

• Nose

• Pharynx

• Larynx

• Vocal Cords

• Trachea

• Bronchi

• Lungs

o Blood Supply to the Lungs


Functions of the Respiratory System


The Respiratory System

o The respiratory system: contributes to homeostasis

• Provides for gas exchange—intake of O2 and elimination of CO2

• Helps adjust the pH of body fluids

o Respiration: the exchange of gases between the

atmosphere, blood, and cells.

o Three basic steps:

• Ventilation (breathing)

• External (pulmonary) respiration

• Internal (tissue) respiration



o Functions of the respiratory system

• Gas exchange: intake of O2 2 for delivery to body

cells and removal of CO2 2 produced by body cells

• Helps regulate blood pH

• Contains receptors for sense of smell

• Filters inspired air

• Produces vocal sounds (phonation)

• Excretes small amounts of water and heat


Respiratory System Anatomy



Structural divisions:

o The upper respiratory system:consist of

• Nose

• Nasal cavity

• Pharynx (throat), and associated

structures.

o The lower respiratory system: consists of

• Larynx (voice box)

• Trachea (windpipe)

• Bronchi (airways)

• Lungs



Functional divisions:

o The conducting zone: consists of a series of interconnecting cavities and tubes both outside and within the lungs.

• the nose, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles

o Function: to filter, warm, and moisten air and conduct it into the lungs.

o The respiratory zone: consists of tubes and tissues within the lungs

• the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli

o Function: the main sites of gas exchange between air and blood.


Nose

o The nose: A specialized organ at the entrance of the

respiratory system

o Two parts:

• External nose: External portion

• Nasal cavity: Internal portion


Nasal cavity

o The nasal cavity: A large space in the anterior aspect of

the skull that lies inferior to the nasal bone and superior

to the oral cavity.

o Duct openings: Duct from the paranasal sinuses (which

drain mucus) and the nasolacrimal ducts (which drain

tears) open in nasal cavity.

o Regions:

• Superior olfactory region: smaller, olfactory function

• Inferior respiratory region: larger, respiratory function

– lined with the respiratory epithelium-pseudostratified ciliated

columnar epithelium with numerous goblet cells.


Nasal cavity


Airway Epithelium

o Ciliated pseudostratified columnar epithelium with goblet

cells produce a moving mass of mucus.


Functions of the Nasal Structures

o Ciliated pseudostratified columnar with goblet cells:

• Lines the nasal cavity

• Warms air due to high vascularity

• Mucous moistens air and traps dust

• Cilia move mucous towards pharynx

o Olfactory epithelium: Detecting olfactory stimuli

o Paranasal sinuses: Modifying speech vibrations as they

pass through the large, hollow resonating chambers.

• Resonance refers to prolonging, amplifying, or modifying a

sound by vibration.


Pharynx


Pharynx

o Structure:

• a funnel-shaped tube about 13 cm (5 in.) long that

• starts at the internal nares and extends to the level of the cricoid cartilage, the most inferior cartilage of the

o Functions:

• Passageway for food and air

• Resonating chamber for speech production

• Tonsils (lymphatic tissue) in the walls protects entryway into body

o Distinct regions: nasopharynx, oropharynx and laryngopharynx


Pharynx


Larynx

o The larynx (voice box): A passageway that connects the

laryngopharynx with the trachea.

o Structure: Contains nine pieces of cartilage:

• Three single cartilages: thyroid cartilage, epiglottis,

and cricoid cartilage

• Three paired cartilages: arytenoid, cuneiform, and

corniculate cartilages

o Function: Voice production

o Vocal folds (true vocal cords): produce sound.

o Taunt vocal folds produce high pitches, and relaxed

vocal folds produce low pitches.


Larynx


Trachea

o The trachea (windpipe):

o Location: anterior to the oesophagus, extends from the

larynx to the primary bronchi level of T5

o Size: 12 cm long and 2.5 cm diameter

o Layers of the tracheal wall:

• Mucosa

• Submucosa

• Hyaline cartilage

• Adventitia


Trachea

o Mucosa: consists of pseudostratified ciliated columnar

epithelium

• Protects from dust and foreign particles.

o Submucosa: Consists of areolar connective tissue that

contains seromucous glands and their ducts.

o Hyaline cartilage:16 to 20 incomplete ‘C’ shaped

cartilage rings

• Provide a semirigid support to maintain patency so that the

tracheal wall does not collapse inward (especially during

inhalation) and obstruct the air passageway.

o The Adventitia: consists of areolar connective tissue

• joins the trachea to surrounding tissues.


Trachea and Bronchial Tree

o The bronchial tree begins at the trachea and ends at the

terminal bronchioles.

o Full extent of airways is visible starting at the larynx and trachea


Bronchi

o Primary bronchi: the trachea divides into a right primary

bronchus and a left primary bronchus supply each lung

• The right primary bronchus is more vertical, shorter, and wider

than the left.

• an aspirated object is more likely to enter and lodge in the right

primary bronchus than the left

o Carina: An internal ridge formed by a posterior and

inferior projection of the last tracheal cartilage, at the

point where the trachea divides into right and left primary

bronchi

• Significance: One of the most sensitive areas of the entire larynx

and trachea for triggering a cough reflex.


Bronchi

o Secondary bronchi: Supply each lobe of the lungs (3

right + 2 left)

o Tertiary bronchi: Supply each bronchopulmonary

segment (10 in each lung)

• Divide into bronchioles which in turn branch repeatedly, divide

into smaller tubes called terminal bronchioles


Bronchial Tree

Structural changes as the branching becomes more

extensive:

o The mucous membrane:

• Gradually changes from pseudostratified ciliated to cuboidal non-

ciliated

o Rings of cartilage:

• Gradually replaced by rings of smooth muscle and then

connective tissue


Bronchial Tree

o Sympathetic nervous system: stimulates adrenal glands to release epinephrine that relaxes smooth muscle.

• dilates airways and improves lung ventilation

o Parasympathetic nervous system: cause contraction of bronchiolar smooth muscle

• constricts of distal bronchiole

o Mediators of allergic reactions such as histamine: Released during asthma attacks or allergic reactions constrict distal bronchiole smooth muscle

o Nebulization therapy = inhale mist with chemicals that relax muscles and reduce thickness of mucous


Pleural Membranes and Pleural

Cavity

o Pleural membrane: A double-layered serous membrane

that enclose and protect each lung

• Visceral pleura covers lungs

• Parietal pleura lines thoracic cavity

o Pleural cavity: A potential space between the visceral

and parietal pleurae

• Contains a pleural fluid secreted by the membranes.

• Reduces friction between the membranes, allowing

them to slide easily over one another during

breathing.


Pleural Membranes and Pleural

Cavity


Lungs

o Shape: Paired cone shaped organs

o Location: in the thoracic cavity; extend from the diaphragm

to just slightly superior to the clavicles and lie against the

ribs anteriorly and posteriorly.

o Enclosed and protected by the pleural membrane.


Lungs

o Shape: Paired cone

shaped organs

o Location: in the thoracic

cavity; extend from the

diaphragm to just slightly

superior to the clavicles

and lie against the ribs

anteriorly and posteriorly.

o Enclosed and protected by

the pleural membrane.


Gross Anatomy of Lungs

o Base, apex (cupula), costal surface, cardiac notch

o Lobes:

• The right lung: three lobes separated by two fissures- Oblique and

horizontal fissure

• The left lung: two lobes separated by one fissure- Oblique fissure


Mediastinal Surface of Lungs

o Blood vessels and airways enter lungs at hilus

o Forms root of lungs

o Covered with pleura (parietal becomes visceral)


Microscopic Anatomy of Lungs

o Bronchopulmonary segment: The segment of lung tissue that each tertiary bronchus supplies

o Lobules: Small compartments of bronchopulmonary segment• Wrapped in elastic

connective tissue

• Each contains an arteriole, a venule, and a branch from a terminal bronchiole


Microscopic Anatomy of Lungs

o Respiratory bronchioles:microscopic sub branches from terminal bronchioles

o Alveolar ducts: Respiratory bronchioles in turn subdivide into several (2–11) alveolar ducts,

o Alveoli: A cup-shaped out-pouching around the circumference of the alveolar ducts (150 million/lung)

o Alveolar sacs: Two or more alveoli that share a common opening


Cells Types of the Alveoli

o Type I alveolar cells:

• Form a continuous lining of the alveolar wall.

• Site for gas exchange.

• Are the most prevalent alveolar cells

o Type II alveolar cells (septal cells):

• Found between type I alveolar cells

• Secrete alveolar fluid containing surfactant

– Surfactant lowers the surface tension of alveolar

fluid, preventing the collapse of alveoli with each

expiration


Other cells types of the Alveoli

o Alveolar dust cells

• Wandering

macrophages that

remove debris

o Fibroblasts:

• Produce reticular

and elastic fibers


Alveolar-Capillary Membraneo Alveolar-capillary membrane/

Respiratory membrane:

• Formed by alveolar and

capillary walls where the

alveoli are in close

proximity to the capillaries

• 0.5 micron thick

• Site for exchange of gases


Blood Supply to the Lungs

o Arterial supply:

• Pulmonary arteries: carry deoxygenated blood from the right

heart to the lungs for oxygenation

• Bronchial arteries: branch from the aorta and deliver oxygenated

blood to the lungs primarily perfusing the muscular walls of the

bronchi and bronchioles

o Venous drainage:

• Four pulmonary veins: Drain into the left atrium

o Ventilation–perfusion coupling:

• Vasoconstriction in response to hypoxia diverts pulmonary blood

from poorly ventilated areas of the lungs to well-ventilated

regions for more efficient gas exchange.


Readings and Resources

o Tortora, GJ & Derrickson, B 2014. Principles of Anatomy and Physiology, 14th edn, Wiley.

o Harris, P, Nagy, S & Vardaxis, N 2010, Mosby’s Dictionary of Medicine, Nursing and Health Professions, 2nd edn, Mosby Elsevier.

o Guyton, AC & Hall, JE 2011, Textbook of Medical Physiology, 12th edn, Saunders Elsevier.

o Marieb, EN & Hoehn, K 2010, Human Anatomy and Physiology, 8th edn, Benjamin Cummings Pearson.

o Moore, KL, Dalley, AF & Agur, AMR 2010, Clinically Orientated Anatomy, 6th edn, Lippincott, Williams & Wilkins.


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