The neural control of breathing Flashcards
How is breathing initiated?
→ Neural activation of respiratory muscles which provide the movement required for ventilation
What do respiratory muscles consist of?
→ Skeletal muscle
What do respiratory muscles require to contract?
→Neural inputs/stimulation to contract
What provides the contractile signal?
→ Innervation from motor neurons synapsing from descending spinal tracts
Which muscles (including accessory muscles) are utilised in quiet/ forced inspiration and expiration?
INSPIRATION:
→quiet breathing: diaphragm
→increased/ forced ventilation: external intercostal muscles (pectorals, sternomastoid and scalene muscles as accessories)
EXPIRATION:
→quiet breathing: elastic recoil
→increased/ forced ventilation: elastic recoil and internal intercostal muscles (abdominal muscles as accessories)
How are basic breathing patterns generated?
→ By neuronal systems within the brainstem
What is the PRG?
→ Pontine respiratory group
What is the DRG?
→ Dorsal respiratory group
What is the VRG?
→ Ventral respiratory group
What are the signals that the CPG receives?
→ pH of arterial blood
→ Amount of CO2 and O2 in arterial blood
→Current lung volume
→ How stretched the lungs are
→ The CPG integrates data from these various neuronal inputs to regulate ventilation
What does the CPG do with these signals?
→ Integrates data from these neuronal inputs to regulate ventilation
Where are the CRC (central chemoreceptors) found?
→ In the medulla
What do CRC do?
→ Indirectly monitors changes in arterial CO2
Why doesn’t the CRC directly respond to changes in blood pH?
→ Responds to changes in H+ within the cerebrospinal fluid
→ H+ cannot cross the blood brain barrier so CRC cannot directly respond to changes in pH
Where are peripheral chemoreceptors found?
→ In the aortic body
What do peripheral chemoreceptors detect?
→ Changes in blood oxygen and CO2, but not pH
What is the hypoxic drive?
→Increased ventilation in response to decreased PaO2
What is sleep apnoea?
→ temporary cessation of breathing during sleep
What are 4 causes of sleep apnoea?
→ Stroke
→ Drugs
→ Central hypoventilation syndrome
→ Altitude
What are the 3 categories of sleep apnoea?
→ Central
→ Obstructive
→ Mixed
What is Cheyne- stokes respiration?
→ Oscillating hyperpnoea and apnoea
How does Cheyne-stokes respiration occur?
→ Apnoea causes compensatory hyperventilation
→ Hyperventilation overcompensates producing hypocapnia
Why is it impossible to asphyxiate yourself?
→ Urge to breathe caused by excess CO2 will be overpowering
→ Acute hypoxaemia results in loss of consciousness ( involuntary breathing begings)
