If the partial pressure of oxygen in the atmosphere is 160 mmHg when the total a
ID: 226921 • Letter: I
Question
If the partial pressure of oxygen in the atmosphere is 160 mmHg when the total atmospheric pressure is 760 mmHg, then why is the partial pressure of oxygen in the lungs always lower, even when the total pressure in the lungs and total pressure in the atmosphere are at equilibrium?
: Focus is on the physiological sequence of events that causes a bulk volume of air to move through the system. (Difficulty level 2)
a.Diaphragm relaxes
b.Diaphragm contracts
c.Old (oxygen depleted) air passes through the trachea, down its pressure gradient
d.Fresh air passes through the trachea, down its pressure gradient
e.Space in the lungs increases (lung volume increases)
f.Space in the lungs decreases (lung volume decreases)
Correct order: _________________________________________
1. If the blood pH is stable at 7.4, then lungs? b. What is the percent saturation of Hbin the blood as it leaves the tissues 2. If the blood pH is stable but slightly alkaline at 7.6, then: lungs? b. What is the percent saturation of Hbin the blood as it leaves the tissues 3. What percentage of hemoglobin unloaded oxygen as it passed through the tissues? In other words, what is the difference in tion before vs. after the blood passed through the tissues? a. At pH 7.4? b. At pH 7.6?Explanation / Answer
As the air moves towards the lungs, it is humidified. This water vapor lowers the partial pressure of oxygen. Also the oxygen is continuously used by the capillaries and there is continuous diffusion of carbon dioxide into the alveoli. This also reduces the partial pressure of O2