Ctrl of Breathing

Question 1

How does the pneumotaxic center contribute to respiration?

Answer 1

regulates respiratory rate

Question 2

How does the apneustic center contribute to respiration?

Answer 2

prolongs inspiration

Question 3

Where are the pneumotaxic and apneustic center located?

Answer 3

pons

Question 4

When the medulla triggers rhythm generating neurons, (inspiration/expiration) occurs; when the signal stops, (inspiration/expiration) occurs.

Answer 4

inspiration
expiration

(these signals trigger motor nerves that activate muscles involved in respiration)

Question 5

Where are gamma efferents located?

Answer 5

muscle

Question 6

How do baroreceptors affect respiration?

Answer 6

signal to medulla to increase respiration when decreased BP sensed

Question 7

Alveolar ventilation is regulated in response to:

Answer 7

arterial PCO2, pH and PO2

Question 8

What is sensed to regulate minute to minute stability of arterial gases and pH?

Answer 8

partial pressure of arterial CO2

metabolism relative to ventilation

Question 9

How do high CO2 levels in the blood affect ventilation?

Answer 9

• -In the extracellular fluid, CO2 forms bicarb and H ions, which are sensed by H sensitive neurons.
• -Medulla senses pH changes
• -Respiration is increased in response

CO2 freely diffuses across BBB?

Question 10

How do chemosensitive cells react to long term elevations in PCO2?

Answer 10

reset themselves to the new nml:

• -bicarb is pumped into BBB via transport protein
• -medulla senses the increased pH and lowers respiratory drive

Question 11

If the respiratory drive is too high (COPD) in response to chronically elevated PCO2, you will see metabolic (acidosis/alkalosis) in response to respiratory (acidosis/alkalosis)

Answer 11

alkalosis
acidosis

**the medulla is sensing decreased pH, which increases respiratory rate; high bicarb crosses BBB to reset ventilation to function at a higher CO2 level

Question 12

What type of channels are present in carotid bodies? How do they work?

Answer 12

O2 sensitive K channel

• -decreased O2 inhibits the channel
• -this depolarizes the cell and increases excitability
• -excitatory neurotransmitters are released to the glossopharyngeal nerve

Question 13

What is sensed by the carotid bodies?

Answer 13

arterial PO2 (not content)

Question 14

Carotid bodies are (fast/slow) responders to gas changes

Answer 14

fast

Question 15

How are central chemoreceptors reset at high altitude (chronic hypoxia)?

Answer 15

• -arterial PO2 decreased due to altitude = carotid body increases alveolar flow (ventilation)
• -this decreases arterial PCO2 which raises pH in brain
• -central chemoreceptors block increased respiratory drive
• -bicarb moves out, which lowers/resets the pH

Question 16

How does the body compensate for respiratory alkalosis?

Answer 16

decreasing plasma bicarb

**this sentence in his notes was confusing