Respiratory System

Anatomy & Physiology

Functions of Respiratory System

Ventilation:

Gas Exchange:

Gas Transport:

Organs of Respiratory System

Nasal CavityPharynx LarynxTracheaBronchiLungs

Air BloodSmaller bronchi Branches of pulmonary arteriesBronchioles ArteriolesAlveolar ducts CapillariesAlveoli Venules Branches of pulmonary veins

Nasal Cavity:

Inhaled air passes from nasal cavity into pharynx. Three regions: Nasopharynx Oropharynx Laryngopharynx

Functions of Larynx:

Structure of Larynx: Nine cartilages connected by muscles & ligaments

Structure of Larynx: Nine cartilages: 3 large unpaired:

6 smaller paired: Posterior View

Anterior View

Anterior Posterior Midsagittal (Section)

Superior

Vocal cords (also called vocal folds or vocal ligaments)

Vocal cords (also called vocal folds or vocal ligaments) are strands of dense regular connective tissue running anteriorly from arytenoid cartilages to thyroid cartilage.

Air moving between them cause them to vibrate.

Trachea:

Cricoid Cartilage

Primary Bronchus

Trachea:

Cross section of neck at level of vertebra cervical 6

Lungs: Occupy most of thoracic cavity

Lungs:

Lungs:

Lungs:

Lungs:

Lungs:

Lungs:

Trachea

Primary bronchi

Secondary bronchi

Tertiary bronchi

(smaller branches)

(bronchioles)

Terminal bronchioles

Respiratory bronchioles

Alveolar ducts

Alveoli

Trachea

Primary bronchi

Secondary bronchi

Tertiary bronchi

(smaller branches)

(bronchioles)

Terminal bronchioles

Respiratory bronchioles

Alveolar ducts

Alveoli

Conducting Zone

Respiratory Zone

Alveoli:

As the bronchi branch and divide, so do the pulmonary arteries and pulmonary veins which accompany them.

At the end, each alveolus is surrounded by many capillaries for the exchange of gassesbetween air (in the alveolus) and blood (in the capillaries).

This air (in the alveolus) and blood (in the capillaries)

Let’s return to ventilation:

Air pressure is measured

Terminology you need to know:

Atmospheric pressure

Intrapulmonary pressure

Intrapleural pressure

Proper ventilation requires that the lungs also expand each time the thoracic cavity expands.

Respiratory Volumes:

TIDAL VOLUME:

Respiratory Volumes:

EXPIRATORY RESERVE VOLUME:

Respiratory Volumes:

INSPIRATORY RESERVE VOLUME:

Respiratory Volumes:

RESIDUAL VOLUME:

Respiratory Volumes:

VITAL CAPACITY:

Respiratory Volumes:

TOTAL LUNG CAPACITY:

Note that all of the air which enters your nose does not reach your alveoli.

Gas Exchange:

Movement of specific gases:

a) From a mixture of gases into a liquid (e.g. oxygen moves from air in the alveoli into blood in

the capillaries)

b) From a liquid into a mixture of gases (e.g. carbon dioxide moves from blood in the capillaries into air in the alveoli)

c) From one liquid into another liquid (e.g. oxygen leaves the blood and diffuses into

extracellular fluid, while carbon dioxide moves from the extracellular fluids into the blood.

Dalton’s Law:

Atmospheric Air:Nitrogen = 78%Oxygen = 21%Water = 0.5%Carbon dioxide = 0.04%Other gases = 0.46% Total = 100%

This mixture of gases exerts a total pressure of approximately 760 mm Hg

Henry’s Law:

(How much of a gas dissolves in a liquid can only be changed by changing its partial pressure, which can only be changed by changing its concentration.)

Thus:

Example #1:

Suppose you have air which is 78% Nitrogen 20% Oxygen 1% Water 1% Carbon dioxide

and you measure how rapidly oxygen diffuses from this air to blood

Then, you change the composition of the air to 75% Nitrogen 14% Oxygen 5% Water 6% Carbon dioxide

How will this affect how much oxygen diffused from the air to the blood?

Example #2:

Suppose you have air which is 78% Nitrogen 20% Oxygen 1% Water 1% Carbon dioxide

and you measure how rapidly oxygen diffuses from this air to blood

Then, you change the composition of the air to 69% Nitrogen 20% Oxygen 5% Water 6% Carbon dioxide

How will this affect how much oxygen diffused from the air to the blood?

Realize:

The composition of air in alveoli does not equal the composition of air in the atmosphere.

a) .

b)

c)

Inspired air: Alveolar air:

78.6% Nitrogen 74.9% Nitrogen 20.8% Oxygen 13.6% Oxygen 0.5% Water 6.2% Water 0.04% Carbon dioxide 5.3% Carbon dioxide

Recall:

Gas exchange has four parts:

Oxygen moves from air to blood in lung Carbon dioxide moves from blood to air in lung Oxygen moves from blood to extracellular fluids in consumer tissues Carbon dioxide moves from extracellular fluids to blood in consumer tissues

Fortunately: All of these gas movements are governed by the same laws of physics (Dalton’s and Henry’s laws).

That is: movement of a gas from one place to another depends on its concentrations in the two places and on its solubility.