Lecture 24: Respiration 3

Question 1

What are circumstances in which breathing is modulated?

Answer 1

conscious control (feed forward), swallowing and vocalisation

Question 2

What is a common breathing pattern during early development?

Answer 2

periodic breathing

Question 3

What is periodic breathing?

Answer 3

waxing-waning pattern of breathing

interspersed and recurrent apneas

Question 4

What does stimulation of pulmonary stretch receptors result in?

Answer 4

termination of inspiration and slowing of respiratory rhythm by activation of Post-I

Question 5

Activation of pulmonary stretch receptors will result in what changes in the respiratory phases?

Answer 5

slowing of respiratory rhythm, prolongation of expiration and inhibition of inspiration

Question 6

Identify the effects on respiratory neurons which are stimulated by the activation of PSRs.

Answer 6

inhibit pre-inspiratory neurons, inhibit inspiratory neurons, excite post-inspiratory neurons and inhibit augmenting expiratory (or late E) neurons

Question 7

What is cardio-respiratory integration?

Answer 7

carefully coordinated interaction between the respiratory and cardiovascular system (autonomic nervous system)

Question 8

What happens when arterial pressure of oxygen decreases? (ventral respiratory column)

Answer 8

increase in firing of peripheral chemoreceptors -> increase in activity of the ventral respiratory column -> increase in activity of the respiratory muscles -> increase in ventilation (tidal volume and respiratory frequency) -> increase in gas change and O2 uptake

Question 9

What happens when arterial pressure of oxygen decreases? (cardiovascular control centres)

Answer 9

increase in firing of peripheral chemoreceptors -> increase in activity of the cardiovascular control centres -> increase in heart rate and vasoconstriction -> increase in circulation -> increase in O2 delivery, gas exchange and O2 uptake

Question 10

Where do carotid bodies and aortic bodies terminate?

Answer 10

in the nucleus of the solitary tract

Question 11

What are Type I and Type II cells?

Answer 11

type I cell = glomus cell

type II cell = glial-like ensheathing cell

Question 12

What do Type I glomus cells respond to?

Answer 12

both low O2 and high CO2

Question 13

What is an example of central chemoreceptors?

Answer 13

RTN = retrotrapezoid nucleus

Question 14

What activates an RTN neuron?

Answer 14

H+ ions from the reaction of CO2 and water

Question 15

What are central chemoreceptors activated by?

Answer 15

raised CO2 or lowered pH

Question 16

What does hypercapnia (raised CO2) evoke in the lungs?

Answer 16

active expiration during late E

Question 17

What do peripheral chemoreceptors respond to?

Answer 17

low oxygen in the blood, higher carbon dioxide in the blood and low pH in the blood

Question 18

What do central chemoreceptors respond to?

Answer 18

high carbon dioxide in the cerebrospinal fluid

Question 19

Where are glomus cells / Type I cells found?

Answer 19

in carotid bodies

Question 20

What do glomus cells respond to and how do they transmit their signals?

Answer 20

hypoxia and hypercapnia, and transmit their signals via paracrine actions to the glossopharyngeal nerve

Question 21

What does activation of both peripheral and central chemoreceptors elicit?

Answer 21

increase in sympathetic nerve activity

Question 22

What does activation of central chemoreceptors lead to?

Answer 22

active expiration

Question 23

How is TASK-2 activated and what happens when it opens?

Answer 23

activated by H+ ions and opening of these channels leads to increased firing of RTN neurons which leads to increased breathing

Question 24

What forms the basis of locomotor-respiratory coupling?

Answer 24

afferent feedback from contracting muscles resets respiratory rhythm
shortening of post-I phase

Question 25

How is the post-I phase shortened during locomotor respiratory coupling?

Answer 25

inhibition of post-I neurons + excitation of aug-E neurons

Question 26

What is phase and respiratory resetting (entrainment) mediated through?

Answer 26

the pontine respiratory group

Question 27

What is entrainment disrupted by?

Answer 27

antagonism of NK1R in the Bötzinger complex

Question 28

What is required for resetting in the Bötzinger complex?

Answer 28

substance P