Question

1. The percentage of Vital capacity that can be expired in one second is decreased in someone with which of the following?

A. Someone with an increased comliance

B. Someone with bronhoconstriction

C. Someone with an incease in VO2 max

2. Which of the following does NOT influence the loading reaction at the lungs?

A. Blood pH

B. The amount of hemoglobin in the blood

C. The p02 graident across the respiratory membrane

D. Pulmonary edema

3. Elevated body temperature, acidosis and/or anemia will?

A. Increase the unloading reaction

B. Cause a left shift in the oxygen-hemoglobin dissoaciation curve

C. Decrease Respiratory rate

Answer 1

1.ans) option B - someone with bronchoconstriction

Explanation - vital capacity that can be expired in the one second is known as forced expiratory volume in 1 second(FEV 1).

FEV 1 is volume of forced vital capacity expired in 1st second of expiration.

It is decreased in obstructive lung diseases like bronchial asthma.

In bronchial asthma, inspiration is normal but expiration is obstructed,therefore FEV1 decreases.

Bronchial asthma is characterized by bronchoconstriction and diameter of airways decreases causing increased resistance to the air flow, eventually producing difficulty in breathing. However, inspiration is possible as expansion of bronchioles does take place but during expiration, the already constricted bronchioles are constricted further causing difficulty in expiration.

So in bronchoconstriction ( e.g. in bronchial asthma), FEV1 decreases.

Other options are incorrect -

Option A is incorrect - As increased compliance seen in restrictive lung diseases like emphysema.

In emphysema,chest expansion is restricted. So FEV1 is normal.

So in increased compliance, FEV1 is normal(not decreased).

Option C is incorrect - As in increased VO2 max seen in increased in cardiac output and during exercise.

In increased VO2 i.e more oxygen consumption , there will be more FEV1 (not decreased).

2.ans) option D- pulmonary edema

Explanation -Loading reaction is binding of hemoglobin to the oxygen forming oxyhemoglobin.

Pulmonary edema can occur when individual is at high altitude.

High altitude causes increase in concentration of 2,3-diphosphoglyceric acid, which promotes unloading reaction i.e dissociation of hemoglobin from oxygen (not promotes loading reaction)

Explanation for other options -

The amount of hemoglobin in the blood influences the oxygen carrying capacity of blood to the tissues in the body.

More the hemoglobin, more the oxygen binds to oxygen and supplied to the tissues.so loading reaction occurs.

Loading reaction occurs i.e binding of hemoglobin to the oxygen when there is high pO2, high blood pH and low temperature. As these factors increase the affinity of hemoglobin to oxygen causing loading reaction.

High pO2 i.e more pO2 pressure gradient across the respiratory membrane.

more the pO2,more the hemoglobin binds to the oxygen.

High pH i.e lesser hydrogen ions concentration promotes loading reaction at the lungs.

3.ans)option A - increases the unloading reaction.

Explanation -

Unloading reaction is dissociation of hemoglobin from oxygen forming deoxyhemoglobin.

Factors promoting unloading reaction are -

High body temperature, acidosis(low blood pH), high pCo2 and anemia.

As these factors promote reduction of affinity of hemoglobin for oxygen forming deoxyhemoglobin, so unloading reaction occurs.

Other options are incorrect -

Option A is incorrect -

As these factors causes unloading reaction, so that oxygen hemoglobin dissociation curve shifts to tight side. (not to left side)

Loading reaction causes shifts curve to the left side.

Option C is incorrect- As these factors causes unloading reaction i.e oxygen dissociates from the hemoglobin.

So lungs compensate it by increasing the respiratory rate (not decreases), so that pO2 is increased and loading reaction occurs.