Lecture 10: Control Of Ventilation

Question 1

Where does rythmogenesis occur?

Answer 1

In the medulla

Question 2

Where is respiration halted?

Answer 2

The section between the medulla and spinal cord

Question 3

Which 2 centres are involved in rythmogenesis?

Answer 3

Dorsal and Ventral respiratory groups

Question 4

What does the DRG do?

Answer 4

• Receives afterrent input
• has respiratory cells that drive the phrenic nerve
• contains cells that are active during inspiration
• corresponds to the nucleus tractus solitarius (NTS)

Question 5

What does the VRG do?

Answer 5

• has outputs to accessory organs
• houses the expiratory motor neurons
• controls the upper airway and vagas stimulation to the ASM via the Nucleus Ambiguus
• has cells active during expo and som in inspo

Question 6

What is the on switch theory?

Answer 6

There are cells that are constant driving the diaphragm to contract but they are connected through interneurons to inhibitory cells that stop the driving

Question 7

The kernel model depends on ______________________________________________________

Answer 7

Pacemaker activity in single neurons

Question 8

Where is the pre-botzinger complex and what does it do?

Answer 8

Just above the VRG and it houses the pacemaker cells

Question 9

Pacemakers in the pre-botzinger complex use _____________ as their neurotransmitter and all _________________________

Answer 9

Glutamate

Depolarise in phase

Question 10

What is apneusis?

Answer 10

Prolonged inspo with short expo

Question 11

Where is the pneumotaxic area and what is its function?

Answer 11

Found in the pons and shortens inspo

Question 12

The pneumotaxic area and vagal afferents modify breathing by modifying the _______________ and ____________

Answer 12

Inspiratory ramp and expiration

Question 13

Where does the phrenic nerve arise from and what does it innervate?

Answer 13

C2-C5 innervates the diaphragm

Question 14

The Nucleus Ambiguus drives the ________________ to the __________ and the _________________ to the _____________

Answer 14

Vagal afferents to the bronchi

Glossopharyngeal nerve to larynx

Question 15

The Nucleus Retroambigualis drives nerves to the _________________ and _________________.

Answer 15

Intercostals and abdominal muscles

Question 16

Define Apnoea:

Answer 16

No breathing resulting from damage to the medulla

Question 17

Define hyperpnea:

Answer 17

Increases breathing

Question 18

Define hypopnea:

Answer 18

Reduced breathing

Question 19

Define hyperventilation:

Answer 19

Metabolically inappropriate increased ventilation

Question 20

Define apneusis:

Answer 20

Prolonged inspo

Question 21

Define gasping:

Answer 21

Prolonged expiration

Question 22

Describe the central chemoreceptors:

Answer 22

Found on the ventral surface surface of the medulla and are bathed in CSF. They respond to changes in pH, some cells are activated by acid and some are inhibited

Question 23

Describe peripheral chemoreceptors:

Answer 23

Found in the carotid and aortic bodies. Carotid body responds to CO2, H+ and O2. Aortic body responds to CO2 and O2. Glomus cells are the detector cells.

Question 24

Describe glomus cells:

Answer 24

• Detect pH, O2 and CO2

- neuronal in origin and show AP and release neurotransmitters

Question 25

How do glomus cells detect pH?

Answer 25

Detect intracellular pH by protonation of Kca channels which results in a decreases K efflux –> hypopolarised –> AP

CO2 and arterial pH change internal pH

Question 26

How is O2 detected?

Answer 26

Requires an O2 sensitive enzyme, haemoxigenase, which is normally bound to O2. If Hb saturation decreases so will haemoxigenase which causes CO production which opens K channels –> keeps cells polarised .’. Not releasing neurotransmitter

Question 27

What happens when O2 < 60mmHg?

Answer 27

Large increase in ventilation

Question 28

Ventilation at a given PaO2 is enhanced by ____________

Answer 28

Increased PaCO2