Gaseous Exchange Flashcards
What is partial pressure?
The pressure exerted by an individual gas when it exists within a mixture of gases.
mmHg stands for millimeters of mercury, the unit of measurement for pressure.
What is the concentration/diffusion gradient?
It explains how gases flow from an area of high concentration to an area of low concentration.
The steeper the gradient, the faster diffusion occurs.
What is the primary purpose of gaseous exchange?
Getting oxygen into the lungs for diffusion into the blood and removing carbon dioxide from the blood.
What percentage of air is composed of oxygen?
Approximately 21 percent.
What happens during the diffusion of oxygen from the alveoli to the blood?
Oxygen diffuses from the alveoli (100 mmHg) into the blood (40 mmHg) until the pressure is equal.
What is the diffusion pathway of oxygen?
alveoli → blood → muscles
What is the diffusion pathway of carbon dioxide?
muscles → blood → alveoli
What is the partial pressure of carbon dioxide in the blood entering the alveolar capillaries?
45 mmHg
What are the percentages of gases in inspired air at rest?
- Oxygen: 21%
- Carbon dioxide: 0.03%
- Nitrogen: 79%
- Water vapour: Varied
What are the percentages of gases in expired air at rest?
- Oxygen: 16.4%
- Carbon dioxide: 4.0%
- Nitrogen: 79.6%
- Water vapour: Saturated
What is the partial pressure of oxygen in the capillary membranes surrounding the muscle?
40 mmHg
What is the partial pressure of carbon dioxide in the tissues compared to blood?
46 mmHg in tissues and 40 mmHg in blood
Fill in the blank: The diffusion of oxygen occurs until _______ is reached.
equilibrium
True or False: The partial pressure of oxygen must be higher in the blood than in the tissues for diffusion to occur.
False
