Control of Respiration

Question 1

Inputs into the medulla

Answer 1

• peripheral chemoreceptors: located @ carotid bodies

- central chemorecptors: located on ventral surface of medulla

Question 2

Respiratory center of brain

Answer 2

medulla

Question 3

Types of peripheral chemoreceptors

Answer 3

1. increases ventilation in response to low arterial O2
2. increases ventilation in response to high arterial PCO2 ==> fast, seconds
3. increases ventilation in response to high arterial [H+] ==> fast, only mediator of response to metabolic acid-base insults

Question 4

Properties of central chemoreceptors

Answer 4

• located @ medulla
• bind protons in CSF, but sense arterial CO2
• response is slow (minutes)
• mediates 80% of ventialtory response to high PaCO2 under long-term conditions

Question 5

Integrated response to high altitude (short-term)

Answer 5

• decrease PIO2 ==> decrease PaO2 ==> increased activation of peripheral O2 receptors ==> increased ventilation ==> increased PaO2
• increased Va ==> decreased PaCO2 ==> decreased activation of central proton receptors ==> some suppression of increased Va ==> initial recovery of PaO2 is incomplete
• compensation occurs over 2-3 days ==> normal PaO2

Question 6

Acclimatization to high altitude

Answer 6

• decreased PaCO2 ==> increased pH/alkalosis = respiratory alkalosis
• compensation: decreased bicarb reabsorption ==> decreased in pH ==> more H+ ==> increased central H+ receptor activation/removal of suppression of ventilation

Question 7

Increased ventilation during exercise

Answer 7

• initially stimulated by increased CO2 consumption

- as Vo2 consumption increases, protons also contribute to increased stimulation