RESPIRATORY RESPONSE TO EXERCISES

RESPIRATORY RESPONSE TO EXERCISES

Q. 1

The following change is noted during exercise.

 A

Blood flow to brain increases with increase in mean systolic blood pressure.

 B

Body temperature increases.

 C

Lymphatic flow from muscle decreases.

 D

Blood flow to muscles increase after half a minute.

Q. 1

The following change is noted during exercise.

 A

Blood flow to brain increases with increase in mean systolic blood pressure.

 B

Body temperature increases.

 C

Lymphatic flow from muscle decreases.

 D

Blood flow to muscles increase after half a minute.

Ans. B

Explanation:

Ans. is. B. Body temperature increases 

Heat is produced whenever muscles contract.

This is due to 2 reasons

  • The maximal efficiency for conversion of nutrient energy into muscle work, even under the best conditions, is only 20 to 25 percent.
  • Almost all the energy used to contract the muscle is converted into heat.
  • Overcoming viscous resistance to the movement of the muscle and joints.
  • Overcoming the friction of blood flowing through the blood vessels.

Q. 2

Blood in splanchnic area during exercise is decreased due to :

 A Venoconstriction with decreased blood flow

 B Venodilation with decreased blood flow

 C

Venodilation with increased blood flow

 D

Venodilation with normal blood flow

Ans. A

Explanation:

A i.e. Venoconstriction with decreased blood flow

During vigrous exercise, constriction of vessels in splanchnic organ, and decreased blood ‘ storage’ in liver & other portion of splanchnic bed occursQ, which may increase the volume of actively circulating blood, perfusion the muscles by as much as 30%.

Contraction of the capacitance vessels in the viscera can pump a litre of blood into the arterial circulation, in less than a minute.


Q. 3 Which of the following is TRUE regarding physiological changes in the brain during moderate exercise?

 A Blood flow is decreased

 B

Blood flow is increased

 C

Blood flow remains unaltered

 D

Blood flow initially increases & then decreases

Ans. C

Explanation:

C i.e. Blood flow remains unchanged


Q. 4

A/E are the features of exercise

 A

Left shift of Hb-O2 dissociation curve

 B

Increase blood supply to muscle

 C

Increase stroke volume

 D

Increase O2 extraction

Ans. A

Explanation:

A i.e. Left shift of Hb-O2 Dissociation Curve

A right shift of Hb – 02 dissociation curve is seen in exercising muscle.

-the right shift occurs because of the accumulation of CO2  and increased temperature of contracting muscle

During exercise

– The contractile muscles need more 02 for energy production.

–    This need is met by increasing the blood supply to the muscles. Cardiac activity increases to increase stroke volume. The capillary bed of the contracting muscle dilates and many previously closed capillaries open up.

–    In contracting muscle the amount of O2 extracted from blood increases (3 fold increase in O2 extraction from each unit of blood). This is because of the right shift of Hb – O2 dissociation curve


Q. 5

Physiological changes during severe exercise are:

 A Hyperventilation in the beginning

 B Hyperkalemia

 C

led Pa O2.

 D

a & b

Ans. D

Explanation:

A i.e. Hyperventilation in the beginning; B i.e. Hyperkalemia

With the onset of exercise, there is an abrupt increase in ventilationQ; followed after a brief pause by further more gradual increase. The increased stimulation is presumably due to psychic stimuli and afferent impulses from proprioceptorsQ in muscles, tendons and joints.

During muscular exercise, increase in 02 consumption is proportionate to the energy expended, and all the energy needs are met by aerobic process. With more muscular exertion, aerobic resynthesis of energy stores cannot keep pace with their utilization and lactate is produced (d/t anerobic breakdown of glucose):

With vigeourous exercise buffering of increased amount of lactic acid, liberates CO2 and this further increases ventilation. With further accumulation of lactic acid, the Tin ventilation outstrip CO2 production and alveolar 13092 falls as does arterial PCO2Q. The decline in Pco2 provides respiratory compensation for metabolic acidosis

Arterial pH and HCO-3 decreaseQ with severe exercise due to lactic acidosis

– Strenuous exercise can cause HyperkalemiaQ by releasing K+ from skeletal muscle.



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