NPB 101 RESPIRATORY SYSTEM QUESTIONS
External respiration - Answers -exchange of gases between lungs and blood
Internal respiration - Answers -Exchange of gases between cells of the body and the
blood
What is the function of respiration? - Answers -To obtain O2 for use by the body's cells
and to eliminate the CO2 the body cells produce
What are the steps of external respiration? - Answers -1. Ventilation or gas exchange
between the atmosphere and air sacs (alveoli) in the lungs
2. Exchange of O2 and CO2 between air in the alveoli and the blood in the pulmonary
capillaries
3. Transport of O2 and CO2 by the blood between the lungs and the tissues
4. Exchange of O2 and CO2 between the blood in the systemic capillaries and the
tissue cells
Ventilation - Answers -gas exchange between the atmosphere and air sacs in the lungs
Trachea - Answers -a large membranous tube reinforced by rings of cartilage (prevent
collapsing), extending from the larynx to the bronchial tubes and conveying air to and
from the lungs; the windpipe.
Bronchioles - Answers -smallest branches of the bronchi; no cartilage to hold them
open; walls contain smooth muscle innervated by the autonomic nervous system:
- parasympathetic stimulation constricts
- sympathetic stimulation (weakly) relaxes
- also responsive to changes in [O2] and [CO2]
Alveoli - Answers -thin-walled inflatable sacs; site of gas exchange - very small space
between alveolus and capillary; [alveolar macrophages guard lumen]; walls consist of a
single layer of flattened type I alveolar epithelial cells; type II alveolar epithelial cells
secrete pulmonary surfactant; pulmonary capillaries encircle each alveolus
How does pulmonary ventilation occur? - Answers -Air flows because of pressure
differences between the atmosphere and the gases inside the lungs. Air moves down its
pressure gradient from higher pressure to lower pressure; like a balloon, lungs have
elastic recoil due to: highly elastic connective tissue and alveolar surface tension
Boyle's Law - Answers -at any constant temperature, the pressure exerted by a gas in
a closed container varies inversely with the volume of gas
Lungs are suspended in _______________ in completely closed box (the thorax) -
Answers -pleural sac
, Pleural sac - Answers -double-walled, closed sac that separates each lung from the
thoracic wall
Pleural cavity - Answers -interior of pleural sac
Intrapleural fluid - Answers -lubricant secreted by surfaces of the pleura
Atmospheric pressure - Answers -The pressure exerted by the weight of the gas in the
atmosphere on objects on the Earth (760 mm Hg at sea level)
Intra-alveolar pressure - Answers -The pressure within the alveoli (760 mm Hg when
equilibrated with atmospheric pressure)
Intrapleural pressure - Answers -The pressure within the pleural sac - the pressure
exerted outside the lungs within the thoracic cavity, usually less than atmospheric
pressure at 756 mm Hg. (Does not equilibrate at rest because it is a closed cavity)
Thermal pressure gradient - Answers -difference in pressure between the lumen of the
alveoli and the pleural cavity
Patrick suffers a puncture wound to the thoracic wall (pneumothorax). How is the
intrapleural pressure expected to change? - Answers -It would equilibrate with the
atmosphere at 760 mm Hg
Patrick suffers a puncture wound to the thoracic wall. How then, would the transmural
pressure gradient change? - Answers -There would be no pressure gradient because
the two pressures would be equal
Patrick suffers a puncture wound to the thoracic wall. What would happen to the lung? -
Answers -It would collapse
Patrick suffers a puncture wound to the thoracic wall. Suppose you were a physician in
the ER and Patrick was your patient, what treatment might be appropriate? - Answers -
Insert a chest tube into lungs so that the air can be removed and the lungs can re-
expand
How does pulmonary ventilation occur? (pt 2) - Answers -Air alternatively flows into and
out of the lungs due to cyclic changes in intra-alveolar pressure.
- Recall that air flows down its pressure gradient, so...
- Air will flow into the alveoli when the atmospheric pressure is greater than the alveolar
pressure = inspiration
- Air will flow out of the alveoli when the atmospheric pressure is greater than the
alveolar pressure = expiration
External respiration - Answers -exchange of gases between lungs and blood
Internal respiration - Answers -Exchange of gases between cells of the body and the
blood
What is the function of respiration? - Answers -To obtain O2 for use by the body's cells
and to eliminate the CO2 the body cells produce
What are the steps of external respiration? - Answers -1. Ventilation or gas exchange
between the atmosphere and air sacs (alveoli) in the lungs
2. Exchange of O2 and CO2 between air in the alveoli and the blood in the pulmonary
capillaries
3. Transport of O2 and CO2 by the blood between the lungs and the tissues
4. Exchange of O2 and CO2 between the blood in the systemic capillaries and the
tissue cells
Ventilation - Answers -gas exchange between the atmosphere and air sacs in the lungs
Trachea - Answers -a large membranous tube reinforced by rings of cartilage (prevent
collapsing), extending from the larynx to the bronchial tubes and conveying air to and
from the lungs; the windpipe.
Bronchioles - Answers -smallest branches of the bronchi; no cartilage to hold them
open; walls contain smooth muscle innervated by the autonomic nervous system:
- parasympathetic stimulation constricts
- sympathetic stimulation (weakly) relaxes
- also responsive to changes in [O2] and [CO2]
Alveoli - Answers -thin-walled inflatable sacs; site of gas exchange - very small space
between alveolus and capillary; [alveolar macrophages guard lumen]; walls consist of a
single layer of flattened type I alveolar epithelial cells; type II alveolar epithelial cells
secrete pulmonary surfactant; pulmonary capillaries encircle each alveolus
How does pulmonary ventilation occur? - Answers -Air flows because of pressure
differences between the atmosphere and the gases inside the lungs. Air moves down its
pressure gradient from higher pressure to lower pressure; like a balloon, lungs have
elastic recoil due to: highly elastic connective tissue and alveolar surface tension
Boyle's Law - Answers -at any constant temperature, the pressure exerted by a gas in
a closed container varies inversely with the volume of gas
Lungs are suspended in _______________ in completely closed box (the thorax) -
Answers -pleural sac
, Pleural sac - Answers -double-walled, closed sac that separates each lung from the
thoracic wall
Pleural cavity - Answers -interior of pleural sac
Intrapleural fluid - Answers -lubricant secreted by surfaces of the pleura
Atmospheric pressure - Answers -The pressure exerted by the weight of the gas in the
atmosphere on objects on the Earth (760 mm Hg at sea level)
Intra-alveolar pressure - Answers -The pressure within the alveoli (760 mm Hg when
equilibrated with atmospheric pressure)
Intrapleural pressure - Answers -The pressure within the pleural sac - the pressure
exerted outside the lungs within the thoracic cavity, usually less than atmospheric
pressure at 756 mm Hg. (Does not equilibrate at rest because it is a closed cavity)
Thermal pressure gradient - Answers -difference in pressure between the lumen of the
alveoli and the pleural cavity
Patrick suffers a puncture wound to the thoracic wall (pneumothorax). How is the
intrapleural pressure expected to change? - Answers -It would equilibrate with the
atmosphere at 760 mm Hg
Patrick suffers a puncture wound to the thoracic wall. How then, would the transmural
pressure gradient change? - Answers -There would be no pressure gradient because
the two pressures would be equal
Patrick suffers a puncture wound to the thoracic wall. What would happen to the lung? -
Answers -It would collapse
Patrick suffers a puncture wound to the thoracic wall. Suppose you were a physician in
the ER and Patrick was your patient, what treatment might be appropriate? - Answers -
Insert a chest tube into lungs so that the air can be removed and the lungs can re-
expand
How does pulmonary ventilation occur? (pt 2) - Answers -Air alternatively flows into and
out of the lungs due to cyclic changes in intra-alveolar pressure.
- Recall that air flows down its pressure gradient, so...
- Air will flow into the alveoli when the atmospheric pressure is greater than the alveolar
pressure = inspiration
- Air will flow out of the alveoli when the atmospheric pressure is greater than the
alveolar pressure = expiration
