Multiple Choice
Which gradient most directly determines the direction that oxygen and carbon dioxide molecules will move between the air in the alveoli and the blood:
22. The Respiratory System
Respiration
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What is the approximate partial pressure of oxygen in the blood as it enters and leaves the capillaries of the alveoli?
A
Enters: 40 mm Hg, Leaves: 46 mm Hg.
B
Enters: 46 mm Hg, Leaves: 40 mm Hg.
C
Enters: 100 mm Hg, Leaves: 46 mm Hg.
D
Enters: 40 mm Hg, Leaves: 100 mm Hg.
Verified step by step guidance1
Understand the concept of partial pressure: Partial pressure refers to the pressure exerted by a single type of gas in a mixture of gases. In the context of blood and alveoli, it is the pressure of oxygen in the blood.
Recognize the role of alveoli in gas exchange: Alveoli are tiny air sacs in the lungs where oxygen is exchanged for carbon dioxide in the blood. The partial pressure of oxygen changes as blood passes through the alveoli.
Identify the normal partial pressure values: In a healthy individual, the partial pressure of oxygen in the blood entering the alveoli is typically around 40 mm Hg, and it increases to approximately 100 mm Hg as it leaves the alveoli after gas exchange.
Analyze the given options: Compare the provided values with the normal physiological values. The correct option should reflect the increase in oxygen partial pressure from entering to leaving the alveoli.
Select the correct answer: Based on the physiological understanding, choose the option where the partial pressure of oxygen enters at 40 mm Hg and leaves at 100 mm Hg, indicating effective gas exchange in the alveoli.
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