Control of lung function (33)

Question 1

What are the 3 major respiratory groups of neurons in the respiratory centre?

Answer 1

• in medulla: dorsal respiratory group and ventral respiratory group
• in pons, pontine respiratory group has two area: pneumotaxic centre and apneustic centre

Question 2

What is DIVE a mnemonic to remember?

Answer 2

Dorsal Inspire Ventral Expire

Question 3

What is the role of the dorsal respiratory group?

Answer 3

• initiates inspiration
• sets and maintains rate of respiration
• integrating centre that gives output to VRG

Question 4

What is the role of the ventral respiratory group?

Answer 4

• expiratory centre
• inactive during quiet, restful breathing
• sends inhibitory impulses to apneustic centre

Question 5

What is the role of the apneustic centre?

Answer 5

• stimulates activity in DRG
• inhibited by pulmonary stretch receptors
• inhibits pneumotaxic centre

Question 6

What is the role of the pneumotaxic centre?

Answer 6

• controls both the rate and the pattern of breathing
• antagonist to apneustic centre, which produces abnormal breathing during inhalation
• limits inspiration, providing ‘inspiratory off-switch’

Question 7

Which nerve drives breathing?

Answer 7

phrenic nerve- innervates diaphragm

Question 8

What cells help keep tight junctions in place in the blood-brain barrier?

Answer 8

glial cells

Question 9

How do the central chemoreceptors in the medulla sense changes in H+?

Answer 9

• H+ cannot dissolve across the endothelial cells, as they are charged
• CO2 can move through (v. lipid soluble)–> combines w/ water to form H+ and bicarbonate in CSF
• chemoreceptors detect H+ in ventral surface of medulla

N.B. CO2 reflects metabolism

Question 10

What are irritant receptors?

Answer 10

• in airways
• afferent receptors within epithelium that detect irritants e.g. particulates, water
• leads to cough–> glottal closure and contraction of respiratory muscles then glottal opening and rapid expulsion of air

Question 11

What are stretch receptors?

Answer 11

• in airway smooth muscle
• detect excessive inflation (Hering–Breuer inspiratory-inhibitory reflex to prevent hyperinflation of lungs)
• inspiration inhibited and expiration stimulated

Question 12

What are J receptors/pulmonary C-fiber receptors?

Answer 12

• next to capillaries of alveoli
• detect accumulation of fluid or identify pulmonary capillary engorgement
• -> increases breathing frequency bc these ^ cause a decrease in oxygenation

Question 13

What is alkalaemia?

Answer 13

refers to higher than normal pH of blood

Question 14

What is acidaemia?

Answer 14

refers to lower than normal pH of blood

snapshot in time

Question 15

What is alkalosis?

Answer 15

circumstances that will decrease [H+] and increase pH

and create alkalaemia

Question 16

What is acidosis?

Answer 16

circumstances that will increase [H+] and decrease pH

Question 17

What can stimulate a rapid compensatory response to change CO2 elimination and so alter pH?

Answer 17

changes in ventilation

–> a low level of CO2 in the blood results from rapid or deep breathing

Question 18

What can stimulate a slow compensatory response to increase/decrease pH?

Answer 18

changes in HCO3- and H+ retention/secretion in the kidneys

Question 19

Where are peripheral chemoreceptors located and which cranial nerves innervate them?

Answer 19

• aortic arch and carotid bodies

- CN IX and X

Question 20

What is the stimulus for peripheral chemoreceptors?

Answer 20

responds directly to changes in PaO2 (mainly), PaCO2

Question 21

How do strong emotions/pain lead to changes in ventilation?

Answer 21

act via hypothalamus, limbic system–> signal respiratory centres–> modify respiratory rate, depth

Question 22

How does exercise lead to a change in breathing?

Answer 22

• efferents from primary motor cortes simultaneously activates skeletal muscle and respiratory centres in medulla
• proprioceptors in moving muscles, tendons+ joints stimulate respiratory centres

Question 23

How does skin input affect breathing in the cold shock response?

Answer 23

• thermoreceptors detect cold water

- leads to hyperventilation/inspiratory gasp