Control of Respiration Flashcards
Where is the major respiration rhythm generation located?
Medulla Oblongata
What network of neurones generates the breathing rhythm?
Pre-Bötzinger Complex
What type of activity do the neurones in the Pre-Bötzinger complex display?
Pacemaker activity
Where is the Pre-Bötzinger complex located?
Near the upper end of the medullary respiratory centre
How does the Pre-Bötzinger complex generate inspiration?
It excites the dorsal respiratory group neurones, whose firing leads to contraction of inspiratory muscles –> inspiration
What happens when the firing of the dorsal respiratory group neurones stops?
Passive expiration
How is hyperventilation/active inspiration initiated?
Increased firing of dorsal neurones excites ventral respiratory group neurones which stimulate the accessory muscles of breathing –> Forceful expiration
Which centre in the pons modifies rhythm?
Pneumotaxic centre
What does the pneumotaxic centre lead to?
Termination of inspiration
When is the pneumotaxic centre stimulated?
When the dorsal respiratory group neurones fire
What could be the consequence of the pneumotaxic centre NOT inhibiting inspiration?
Apneusis - breathing would consist of prolonged inspiratory gasps with brief expiration
What do impulses from the apneustic centre lead to?
Excitation of the inspiratory area of the medulla; prolonging inspiration
From where do higher brain centres send stimuli to control respiration?
Cerebral cortex
Limbic system
Hypothalamus
What is the Hering-Breuer Reflex?
Pulmonary stretch receptors are activated during inspiration if tidal volume is much greater than 1L. Afferent discharge inhibits inspiration to prevent over-inflation of lungs during hard exercise
Where are joint receptors located?
In the veins
What do impulses from moving limbs sent to joint receptors lead to?
Increase breathing
What stimulates juxta-pulmonary receptors (J-receptors)?
Pulmonary capillary oedema or pulmonary embolism
What does stimulation of J-receptors leads to?
Rapid shallow breathing
What results when baroreceptors sense a decrease in BP?
Increased ventilatory rate
Which factors may increase ventilation during exercise?
Reflexes from body movement Adrenaline release Impulses from cerebral cortex Increase in body temperature Later on: Accumulation of carbon dioxide and hydrogen ions
Explain the Cough Reflex
Irritation/tightening of the airways leads to afferent discharge stimulating the sequence:
a short breath intake
closure of the larynx
contraction of abdominal muscles (increasing intra-alveolar pressure)
Opening of the larynx
Expulsion of air at high speed
What is the physiological benefit of the cough reflex?
Helps clear airways of dust, dirt or excessive secretions
Where is the cough reflex centred?
In the medulla oblongata
Chemical control of respiration involves negative feedback control of mainly _______ blood cast tension which is measured by chemoreceptors.
Carbon dioxide
