Respiratory Physiology: Ventilation Control

Question 1

Ventilation control require stimulation of what muscles during inspiration

Answer 1

Skeletal

Question 2

Where does ventilation control occur via

Answer 2

Phrenic (to diaphragm) and intercostal nerves (to external intercostal muscles)

Question 3

Where does ventilation control reside

Answer 3

ill-defined centres located in the pons and medulla

Question 4

What is PRG and what does it modulate

Answer 4

Pontine respiratory group located in the Pons and it modulates DRG and VRG

Question 5

What does VRG and DRG stand for

Answer 5

Ventral Respiratory Group and Dorsal Respiratory Group

Question 6

What does VRG control

Answer 6

Expiration (tongue, pharynx and larynx)

Question 7

What does DRG control

Answer 7

Inspiration (via phrenic and intercostal muscles)

Question 8

What are the 4 basis’ of rhythm of respiration

Answer 8

1. Emotion (via limbic system)
2. Voluntary over-ride (via higher centres in the brain)
3. Mechano-sensory input from the thorax (stretch reflex to prevent over-expansion)
4. Chemoreceptors which detect chemical composition of the blood (PCO2, PO2 and PH)

Question 9

Which of the 4 basis of rhythm is the most significant

Answer 9

Chemoreceptors

Question 10

Where is the central chemoreceptor located

Answer 10

Medulla

Question 11

What is the stimuli which activates the central chemoreceptor

Answer 11

Responds directly to H+ (directly reflects PCO2)

Question 12

Where do these changes occur and how does this effect the ventilatory drive

Answer 12

Occurs in the CSF. CO2 combines with H20 to form carbonic acid and H+ and is the primary ventilatory drive

Question 13

Hypercapnea

Answer 13

Raised PCO2 in CSF

Question 14

Does the central chemoreceptor respond directly to changes in the plasma (Y/N)

Answer 14

N

Question 15

What crosses the blood brain barrier when PCO2 in arterial blood increases?

Answer 15

H+

Question 16

Where are the peripheral Chemoreceptors located

Answer 16

Carotid and Aortic bodies

Question 17

What is the stimuli which activates the peripheral chemoreceptor

Answer 17

Responds primarily to plasma [H+} and PO2 and is the secondary ventilation drive

Question 18

What happens if plasma pH falls [H+ increases]

Answer 18

Acidosis, ventilation is stimulated

Question 19

What happens if plasma pH increases [H+ falls]

Answer 19

Alkalosis, vomiting and ventilation will be inhibited

Question 20

Common drugs affecting respiratory centres

Answer 20

Barbiturates and Opioids
Gaseous anaesthetic agents
Nitrous Oxide

Question 21

How do Barbiturates and Opioids effect Respiratory Centres

Answer 21

They depress respiratory centres that can lead to respiratory failure

Question 22

How do gaseous anaesthetic agents effect Respiratory Centres

Answer 22

Increase RR but decrease Tidal Volume so decrease Alveolar Ventilation

Question 23

How does nitrous oxide effect the respiratory centres

Answer 23

blunts peripheral chemoreceptors response to falling arterial oxygen