Physio- Control Of Breathing

Question 1

What nucleus is responsible for inhibiting inspiration?

Answer 1

Pneumotaxic center
It controls the tidal volume and regulates respiratory rate/ breathing

Question 2

Which nucleus in the medullary center is responsible for expiration?

Answer 2

Expiratory center

Note: it is located in the VRG and is not active during quite breathing and active during quiet and forceful expiration.

Question 3

State the function of the DRG.

Answer 3

It is responsible for the inspiratory center and controls the basic rhythm of breathing and the frequency of inspiration

Question 4

Hypoxemia induces hyperventilation by direct action of?

Answer 4

Peripheral chemoreceptors (aortic bodies and carotid chemoreceptors)

Question 5

J receptors induces hyperventilation by what mechanism?

Answer 5

Engorgement of pulmonary capillaries and increase in interstitial fluid.

Question 6

Brain stem (medullary chemoreceptors) alters the breathing rate by changes in what?

Answer 6

pH.
An decreae - hyperventilation
A increase - hypo ventilation

Question 7

What are the responses to the respiratory system during exercise?

Answer 7

Increase in:
O2, co2, breathing rate, cardiac output, pulmonary blood flow, right shift in O2 curve, P50, unloading of O2.
There is no change in pulmonary/alveolar pressure.
Decrease in:
pH, affinity of O2 and physiological dead space
V/Q ratio is more even

Question 8

What the responses to the respiratory system during high altitude?

Answer 8

Decrease:
Atmospheric pressures, alveolar O2, arterial O2, affinity for O2

Increase:
Breathing rate, pulmonary resistance and pressure, P50, unloading of O2.

Note: a decrease in arterial PO2 leads to hypoxia which leads to production of EPO which increases the synthesis of blood and increase blood viscosity

Question 9

State the effects of the following brain cuts on respiration?

A) pons and medulla
B) medulla and spinal cord
C) apneustic and pneumotaxic center
D) above the pons

Answer 9

A) pons and medulla - breathing is irregular
B) medulla and spinal cord - breathing stops
C) apneustic and pneumotaxic center - inspiration is prolonged
D) above the pons- breathing is normal but control is lost

Question 10

A regional decrease in alveolar oxygen levels likely results into which of the following
Vasoconstriction
Reduced perfusion in that region
Increased V/Q
Hypoventilation
Actelisis

Question 11

Pulmonary vasoconstriction will likely be caused by? Explain.

Answer 11

A decrease in alveolar PO2. This results in an increase in pulmonary resistance and a decrease in pulmonary arterial pressure to maintain blood flow.

Question 12

With respect to hypoxemia, what is the effect of right to left shunt on arterial blood pressure and the A—a gradient?

Answer 12

Arterial PO2 decreased and A-a gradient decreases.
This is due to the continuous mixing of venous blood with oxygenated blood.

Question 13

State the causes of hypoxemia.

Answer 13

Hypoventilation (decrease alveolar PO2)
Right to left shunts
Diffusion deflects
High altitude
V/Q deflects

Question 14

With respect to hypoxemia, what is the effect of the following on arterial blood pressure and the A—a gradient?
A) High altitude
B) Hypoventilation
C) V/Q defects
D) Diffusion defects
E) Right to left shunts

Answer 14

A) Decrease, normal gradient
B) Decrease, normal gradient
C) Decrease, Increase
D) Decrease, Increase
E) Decrease, Increase

Question 15

In the lung, alveolar hypoxia results in?

Answer 15

Vasoconstriction

Question 16

In the organs of the body, hypoxia results in what?

Answer 16

Vasodilation