Control of Ventilation

Question 0

Define coning.

Answer 0

Swelling of the brain leading to squeezing of the brain through the foramen magnum

Question 1

Where does respiratory rhythm originate?

Answer 1

The medulla, rhythmic signals sent by hypoglossal (CNXII).

Therefore vulnerable with raised intra-cranial pressure and coning.

Question 2

Which respiratory neurons in the medulla fire during inspiration?

Answer 2

Dorsal respiratory group, they stimulate muscles of inspiration

Question 3

Which group of neurons in the medulla are responsible for expiration?

Answer 3

Ventral respiratory group

Question 4

What are the pacemaker cells called and where are they located?

Answer 4

pre-Botzinger complex - located in the VRG

Question 5

What is the pontine respiratory group responsible for?

Answer 5

Fine tune respiratory rhythm by setting volume at which lungs stop inflating/deflating

Question 6

How is the vagus nerve involved in the nose and upper airways?

Answer 6

Sneezing, coughing, aspiration reflex, diving reflex

Question 7

Describe the Hering-Breuer reflex.

Answer 7

Lung deflation stimulates lung inflation muscles
Lung inflation stimulates lung deflation muscles
Pulmonary stretch receptors detect lung volume

Question 8

What are the J receptors for?

Answer 8

They are in the alveolar walls, next to capillaries.
Engorged capillaries → increased interstitial fluid → Vagus → Dyspnoea
The mechanism for difficulty breathing in HF

Question 9

What are irritant receptors for?

Answer 9

They cause bronchoconstriction when noxious stimuli detected.

Question 10

How do chemoreceptors control ventilation?

Answer 10

Adjusts ventilation in the alveoli to match changes in VO2, VCO2 to keep PAO2 and PACO2 (and therefore PaO2 and PaCO2) within normal limits

Question 11

How are PaO2 and PaCO2 kept constant during exercise?

Answer 11

Increasing alveolar ventilation, unless work rates get really high!

Question 12

In normal physiology, what is the main driver of breathing? O2 or CO2?

Answer 12

CO2

Question 13

At low PO2, what is the main driver of breathing?

Answer 13

O2

Acidosis also stimulates ventilation

Question 14

How does hypoxia affect the response to alveolar PCO2 levels?

Answer 14

Hypoxia increases sensitivity to PCO2

Question 15

Where are the central chemoreceptors located and how do they regulate breathing?

Answer 15

They are located in the ventrolateral medullary surface
Respond to arterial PCO2 and pH
If blood flow to the brain is blocked → hyperventilation

Question 16

What is another name for peripheral chemoreceptors? and how do they work?

Answer 16

Heymans. They are located in the carotid and aortic bodies.
The carotid body is sensitive to PO2 decrease, some increase in PCO2 and pH → glossopharyngeal nerve → medulla → hyperventilation