Lecture 24: Respiration 3 Flashcards
What are circumstances in which breathing is modulated?
conscious control (feed forward), swallowing and vocalisation
What is a common breathing pattern during early development?
periodic breathing
What is periodic breathing?
waxing-waning pattern of breathing
interspersed and recurrent apneas
What does stimulation of pulmonary stretch receptors result in?
termination of inspiration and slowing of respiratory rhythm by activation of Post-I
Activation of pulmonary stretch receptors will result in what changes in the respiratory phases?
slowing of respiratory rhythm, prolongation of expiration and inhibition of inspiration
Identify the effects on respiratory neurons which are stimulated by the activation of PSRs.
inhibit pre-inspiratory neurons, inhibit inspiratory neurons, excite post-inspiratory neurons and inhibit augmenting expiratory (or late E) neurons
What is cardio-respiratory integration?
carefully coordinated interaction between the respiratory and cardiovascular system (autonomic nervous system)
What happens when arterial pressure of oxygen decreases? (ventral respiratory column)
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
What happens when arterial pressure of oxygen decreases? (cardiovascular control centres)
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
Where do carotid bodies and aortic bodies terminate?
in the nucleus of the solitary tract
What are Type I and Type II cells?
type I cell = glomus cell
type II cell = glial-like ensheathing cell
What do Type I glomus cells respond to?
both low O2 and high CO2
What is an example of central chemoreceptors?
RTN = retrotrapezoid nucleus
What activates an RTN neuron?
H+ ions from the reaction of CO2 and water
What are central chemoreceptors activated by?
raised CO2 or lowered pH
What does hypercapnia (raised CO2) evoke in the lungs?
active expiration during late E
What do peripheral chemoreceptors respond to?
low oxygen in the blood, higher carbon dioxide in the blood and low pH in the blood
What do central chemoreceptors respond to?
high carbon dioxide in the cerebrospinal fluid
Where are glomus cells / Type I cells found?
in carotid bodies
What do glomus cells respond to and how do they transmit their signals?
hypoxia and hypercapnia, and transmit their signals via paracrine actions to the glossopharyngeal nerve
What does activation of both peripheral and central chemoreceptors elicit?
increase in sympathetic nerve activity
What does activation of central chemoreceptors lead to?
active expiration
How is TASK-2 activated and what happens when it opens?
activated by H+ ions and opening of these channels leads to increased firing of RTN neurons which leads to increased breathing
What forms the basis of locomotor-respiratory coupling?
afferent feedback from contracting muscles resets respiratory rhythm
shortening of post-I phase
How is the post-I phase shortened during locomotor respiratory coupling?
inhibition of post-I neurons + excitation of aug-E neurons
What is phase and respiratory resetting (entrainment) mediated through?
the pontine respiratory group
What is entrainment disrupted by?
antagonism of NK1R in the Bötzinger complex
What is required for resetting in the Bötzinger complex?
substance P
