Question

A normal expiration during quiet breathing:

Select one:

a. is an active process involving muscle contraction.

b. occurs when the diaphragm and external intercostal muscles relax.

c. is not affected by the elastic properties of the lungs.

d. requires more muscle contractions than inspiration.

e. occurs due to the contraction of the diaphragm and elevation of the ribs.

Question 33

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Question text

After hyperventilating for several minutes:

Select one:

a. blood pH would drop and inhibit inspiration.

b. blood pH will rise and stimulate expiration.

c. O₂ in the lungs has not had time to diffuse into the blood.

d. the level of O₂ has increased and inhibits the inspiratory center.

e. the level of CO₂ decreases below the level necessary to stimulate the inspiratory center.

Answer 1

1. Answer ; B) occurs when the diaphragm and the external intercostal muscles relaxes.

Reason ; In a resting state, this phase of respiration is achieved by relaxation of these muscles and not by the contraction. Contraction will cause opposite movement and the air will not get out of the lungs. This process will also affect the elasticity of the lungs. Therefore the above mentioned option is appropriate during the time of exhalation.

33. Answer ; E) the level of the CO2 decreases below the level necessary to stimulate the inspiratory center.

Reason ; In this type of abnormal respiration, the CO2 level would be reduced to severe extent. Although the pH level would be raised in this condition, it will not stimulate the expiration. The inspiration can be stimulated with a certain level of decreased CO2 , but in this condition the individual will experience severe drop which is mentioned in above statement. Other statement are not relevant to the given condition, therefore the above mentioned statement is the appropriate one.