Chemical Control of Breathing

Question 1

What happens to pO2 and pCO2 in hyperventilation?

Answer 1

pO2 rises

pCO2 falls

Question 2

What happens to pO2 and pCO2 in hypoventilation?

Answer 2

pO2 falls

pCO2 rises

Question 3

What does hypercapnia do to plasma pH?

Answer 3

Leads to a fall in plasma pH

Question 4

What does hypocapnia do to plasma pH?

Answer 4

Leads to a rise in plasma pH

Question 5

Where are peripheral chemoreceptors located?

Answer 5

Carotid and aortic bodies

Question 6

What do large falls in pO2 stimulate?

Answer 6

1) Increased breathing
2) Changes in heart rate
3) Changes in blood flow distribution - eg increasing flow to brain and kidneys

Question 7

Where are central chemoreceptors located?

Answer 7

Medulla of the brain

Question 8

Central chemoreceptors respond to changes in pH of what?

Answer 8

CSF

Question 9

What is CSF [HCO3-] controlled by?

Answer 9

Choroid plexus cells

Question 10

Is the blood brain barrier permeable or impermeable to HCO3-?

Answer 10

Impermeable

Question 11

What is the range for pCO2?

Answer 11

4.7-6.0 kPa

Question 12

What is the range for pO2?

Answer 12

9.3-13.3 kPa

Question 13

What is the range for bicarbonate?

Answer 13

22-26mmol/L

Question 14

What is type I respiratory failure?

Answer 14

Type 1 respiratory failure is defined as a low level of oxygen in the blood (hypoxemia) without an increased level of carbon dioxide in the blood (hypercapnia)

Question 15

What is type II respiratory failure?

Answer 15

Type 2 respiratory failure is caused by inadequate alveolar ventilation; both oxygen and carbon dioxide are affected.