Neural control of breathing Flashcards
Which respiratory/accessory muscles are used during forced inspiration?
Respiratory: External intercostals
Accessory: Pectoral, sternomastoid, scalene
Which respiratory/accessory muscles are used during forced expiration?
Respiratory: Elastic recoil, internal intercostals
Accessory: Abdominals
Which type are all respiratory muscles?
Skeletal
Therefore require nervous stimulation in order to contract
What region of the brain determines basic ventilation
The medulla and the pons
Inside the brainstem
The bundle of neurons controlling ventilation is known as the CPG (central pattern generator) sometimes known as the respiratory pattern generator) RPG
Which types of receptors does the CPG recieve imput from?
Central and peripheral chemoreceptors
What do the chemoreceptors detect?
Levels of CO2 (central)
Levels O2 and pH (peripheral)
Where are the central chemorecptors located?
Medulla part of brainstem
How do the Central respiratory chemoreceptors (CRC) monitor changes in Pa CO2 ?
Indirectly; it detects changes in pH in cerebrospinal fluid
Why do CRCs not respond to changes in pH directly?
H+present within arterial blood cannot pass through the blood-brain barrier as they are charged
however arterial
CO2canpass through the blood-brain barrier into the CSF, where it will then react to produce carbonic acid, and the resulting H+activates CRCs
What do peripheral chemoreceptos do?
signal to medullar centres to increase respiration
What type of cells do peripheral chemoreceptors consist of? Where are they present?
type-I glomus cells
Carotid and aortic bodies
What do peripheral chemoreceptors detect?
Levels of O2, CO2 and pH within arterial blood
What two respiratory groups does the medulla contain?
Dorsal and ventral respiratory groups
What does the dorsal group control?
Somatic motor neurons for inspiration
What does the ventral group control?
Somatic motor neurons for expiration
Why is ventilation subject to emotions and voluntary control?
The pons receives input from higher brain centres
Via which feedback loop do the chemoreceptors operate?
Negative feedback
What is hypoxic drive?
increased ventilation in response to decreased PaO2
Potential causes of central breathing dysfunction:
Drugs (barbituates/opiods an cause inhibtion of brainstem)
injury (stroke/trauma)
Congenital defevts in brainstem signalling processes
Insufficient development
Hypocapnia
What are central sleep apnoeas
dysfunction in the central nervous system processes that initiate breathing,
temporary cessation of the automated breathing during sleep
pathways involved in initiating breathing can no longer function
What is cheyne stokes respiration?
abnormal breathing pattern and central sleep apnoea
involving an oscillating pattern of apnoea and hyperpnoea
Explain what happens in cheyne stokes respiration
Apnoea causes hypercapnia and hypoxema
triggers compensatory hyperventilation
This causes hypocania and alkalosis
this decreases respiratory drive causing a period of apnoea
Cycleeeeeeee
