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What is the primary function of the respiratory system?
What is the secondary (second most important) function of the respiratory system?
Acid-base balance via CO2 removal
What are the 5 major functions of the respiratory system?
- 1) gas exchange
- 2) acid-base balance
- 3) phonation
- 4) pulmonary defense mechanisms
- 5) pulmonary metabolism and handling of bioactive materials
Approximately how many alveoli are there in the human lungs?
About how many pulmonary capillaries are there in each alveolus?
- Nearly 1000 capillaries per alveolus
- Each alveolus is almost completely enveloped in pulmonary capillaries
What is the approximate surface area available for gas exchange?
- 50-100 square meters
- Average is 80 square meters
- About the size of 900 square feet
By what mechanism does gas exchange take place?
What is the role of surfactant in alveoli?
What, besides diffusion, promotes CO2 movement out of the RBC?
Where does gas exchange occur?
What is the partial pressure of oxygen in dry air?
21% * 760mmHg = 159mmHg
What is the vapor pressure of water at normal body temperature (37 degrees C)?
What is the total pressure of air after being warmed and moistened in the trachea?
760 - 47 = 713mmHg
What is the partial pressure of oxygen in the trachea?
- 21% * 713 = 149mmHg
- MUST subtract the partial pressure exerted by water vapor from atmospheric pressure BEFORE calculating the partial pressure of inspired oxygen
Describe type I alveolar cells
- AKA pneumocytes
- Flat and form tight junctions with one another
- Prevent passage of large, oncotic molecules into alveolus
Describe type II alveolar cells
- Interspersed among type I cells
- Produce pulmonary surfactant that lines alveoli
Describe alveolar macrophage
Phagocytic cells that destroy inspired particles like bacteria
Describe the progression of conducting airways
- 1) Trachea
- 2) right and left main bronchi
- 3) lobar bronchi
- 4) segmental bronchi
- 5) Terminal Bronchioles
How many generations of airways are there?
What generation is the trachea?
What is the first generation of airway?
Right and left mainstem bronchi
What is the difference between the right and left main bronchi?
Right is more parallel to trachea and larger diameter than left
How many generations compose the conducting zones?
What are the most distal conducting airways?
What generation are terminal bronchioles?
What portion of the conducting zone is deadspace? What is the volume?
What is another term for deadspace created by the conducting zone?
What structures are included in anatomic deadspace?
Airways from nose and lips down to alveoli-free terminal bronchioles
What is the function of the conducting zone?
Move air to the area where gas exchange occurs
By what mechanism does the conducting zone move air?
What airway generations make up the transitional zone?
What structures are included in the transitional zone?
- Appearance of alveoli
- Respiratory bronchioles
What airway generations make up the respiratory zone?
What structures are included in the respiratory zone?
- Alveolar ducts lined with alveoli
- Alveolar sacs
What is the volume of the respiratory zone?
What is the mechanism of gas movement in the respiratory zone?
What blood supplies do the lungs receive?
- 1) pulmonary arteries
- 2) bronchial arteries
Besides pulmonary arteries, what other arteries carries deoxygenated blood?
Umbilical arteries in fetus
What portion of cardiac output do pulmonary arteries receive?
What is the mean pulmonary artery pressure?
What is the average diameter of capillaries that supply alveoli?
- 7-10 micrometers
- Just large enough for RBC to pass single-file
How do pulmonary capillaries form a continuous sheet of blood in alveolar wall?
The lengths of capillary segments are short
What is the thickness of the blood-gas barrier?
How long does a RBC normally spend in the pulmonary capillary network?
How many alveoli does a RBC normally traverse in pulmonary capillary network?
What structures do bronchial arteries supply?
What happens to bronchial arteries at the level of respiratory bronchioles?
- Anastomose with pulmonary artery capillaries
- Blood from bronchial circulation partially drains into pulmonary veins creating a small PHYSIOLOGICAL shunt (right to left)
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