Control of ventilation

Question 1

What nerves if severed will lead to breathing being stopped?

Answer 1

Phrenic nerve origin

C3 to C5

Question 2

Where are the respiratory centres in the brain?

Answer 2

Pons and medulla

Question 3

Where does the phrenic nerve innervate?

Answer 3

the diaphragm

Question 4

Where does the intercostal nerve innervate?

Answer 4

External intercostal muscles

Question 5

Dorsal respiratory group

Answer 5

Primarily muscles of inspiration

Question 6

Ventral respiratory group

Answer 6

Output to expiratory and some inspiratory

Question 7

What 3 structures do the VRG target? Why?

Answer 7

Larynx, pharynx and tongue muscles - to keep muscular tone and patency

Question 8

What 4 things modulate the rhythm of respiratory centres?

Answer 8

• Emotion
• voluntary over ride
• mechano receptor input from thorax
• chemical composition of blood

Question 9

What is the most significant modulator of the respiratory centres?

Answer 9

Chemoreceptors detecting change in the chemical composition of the blood

Question 10

Central chemoreceptors - where?

Answer 10

Medulla

Question 11

What do central chemoreceptors respond to?

Answer 11

Directly to H+ which reflects the CO2

Question 12

Which type is the primary ventilatory drive?

Answer 12

Central chemoreceptors

Question 13

Where is the changes detected by central chemoreceptors detected?

Answer 13

CSF around the brain

Question 14

What is hypercapnia?

Answer 14

Raised PCO2

Question 15

Do central chemoreceptors respond directly to change in {H+} change?

Answer 15

No

Question 16

Does CO2 or hydrogen cross the blood brain barrier?

Answer 16

CO2

Question 17

What does an increase in hydrogen do to breathing?

Answer 17

Increase PaCO2 which leads to reflex stimulation and leads to hyperventilation

Question 18

What are the peripheral chemoreceptors?

Answer 18

Carotid and aortic bodies

Question 19

What do peripheral chemoreceptors respond to?

Answer 19

Primarily to plasma [H+] and PaO2

Question 20

When is there a reflex stimulation of ventilation?

Answer 20

Rise in [H+] or fall in PaO2

Question 21

Do peripheral chemoreceptors respond to Pa02 or oxygen content?

Answer 21

Pa02

Question 22

Suggest a scenario which would lead to increased plasma pH

Answer 22

Vomiting

Question 23

What leads to a large degree of voluntary control over breathing?

Answer 23

Descending neural pathways from cerebral cortex -> respiratory motor neurons

Question 24

Barbiturates and opioids

Answer 24

Depress respiratory centres and overdose leads to respiratory fail

Question 25

Nitrous oxide

Answer 25

Sedative which blunts peripheral chemoreceptors responding to PaO2 and is a problem in COPD

Question 26

Nitrous oxide and COPD

Answer 26

Go into hypoxic drive and oxygen will aggrevate the situation as they rely on low oxygen levels to begin breathing again

Question 27

What is swallowing always followed by?

Answer 27

Expiration

Question 28

Why is swallowing followed by an expiration?

Answer 28

So particles are dislodged outwards from glottis