Control of respiration Flashcards
Where in the brain is the major rhythm generator of respiration?
The medulla oblongata
What is believed to the breathing rhythm generator of the medulla oblongata?
A network of neurones called the Pre-Bötzinger complex, located near the upper end of the medullar respiratory centre
How does the Pre-Bötzinger complex induce the respiratory rhythm?
They display pacemaker activity, exciting the dorsal respiratory group neurones, which fire in bursts
These bursts lead to contraction of the inspiratory muscles and cause inspiration
When firing stops passive expiration occurs
How does the Pre-Bötzinger complex induce active expiration?
Increased firing of the dorsal neurones excites the ventral respiratory group neurones, which excites the internal intercostal and abdominal muscles
Where is the main centre for breathing rhythm modification?
The pons in the brainstem
How is inspiration terminated?
Stimulation of the pneumotaxic centre of the pons terminates inspiration
This occurs when the dorsal respiratory neurones fire, allowing for passive expiration
What would occur if inspiration was not terminated by the pneumotaxic centre?
Breathing would consist of prolonged inspiratory gasps with brief expiration
This is called apneusis
How is inspiration elongated if necessary?
The apneustic centre excites the inspiratory area of the medulla, prolonging inspiration
Which regions of the brain influence the respiratory centres?
The cerebral cortex
The limbic system
The hypothalamus
What influences the respiratory centres of the brainstem?
Higher brain centres
Stretch receptor in the walls of the bronchi and bronchioles
Juxtapulmonary receptors
Joint receptors
Baroreceptors
What stimulates the juxtapulmonary receptors to influence the respiratory centres?
Pulmonary capillary congestion
Pulmonary oedema
Pulmonary embolism
How do pulmonary stretch receptors work?
They are activated during inspiration
Afferent discharge from the receptors inhibits respiration at large tidal volumes
This is the Hering-Breuer reflex
What is the important of pulmonary stretch receptors?
They may be important in newborn babies and in preventing hyperinflation during exercise
What is the function of joint receptors in breathing?
Impulses from moving limbs reflexly increases breathing rate, probably contributing toe increased ventilation during exercise
What factors increase ventilation during exercise?
Joint receptors
Adrenaline release
Impulses from the cerebral cortex
Increase in body temperature
Accumulation of CO2 and H+ in later exercise
