s4. neural control of breathing

Question 1

phrenic nerves originate from and supply what?

Answer 1

C3, C4, C5

diaphragm

Question 2

intercostal muscles- which processes are they used for

which nerve supplies them?

Answer 2

inspiration = external intercostal

expiration= internal intercostal AND innermost intercostal
> primarily passively mediated by elastic recoil of lungs but muscles can assist

supplied by intercostal nerves

Question 3

what is a pattern generator

Answer 3

specialised circuits within CNS which facilitate stereotyped behaviour essential for survival
> set given frequency

Question 4

what’s normal resp rate?

Answer 4

~12 breaths per min

> set by respiratory pattern generator

Question 5

what sensory info does RPG recieve?

Answer 5

• pO2> if drops RPG ventilate more
• pCO2> if inc, inc resp rate to blow off xs CO2 to maintain pH
• pH
• lung stretch > info from vagus nerve (CN10). tells when inspiration ends and expiration begins to prevent hyperinflation damage

Question 6

where is the respiratory pattern generator located?

Answer 6

within medulla

Question 7

what is ondines curse?

Answer 7

• rare disease
• following brainstem injury/ strokes
• pattern generator destroyed>only voluntary connections kept > patient has to think about breathing. > when sleep have to go on ventilatory support

Question 8

what is the system of mutual inhibiton? importance?

Answer 8

inspiratory neurone can inhibit expiratory neurone and visa versa
>ensures only ever inspiring OR expiring (not both)

Question 9

what are the inputs to RPG?

Answer 9

• central chemoreceptors
• CN IX (9- glossopharyngeal> chemical info from peripheral chemoreceptors)
• CN X (10- vagus > stretch and chemical info)