Week 17: (A) Control of Heart Rate Flashcards
Is heart rate innervate by para and sympathetic systems?
YES but predominately the autonomic.
How does the autonomic system affect HR?
changing slope of pacemaker potential
What is the changes heart rate called?
chronotropic effect
What neurotransmitter does the parasympathetic neurone release?
ACh to muscarinic receptors
What neurotransmitter does the Sympathetic neurone release?
Noradrenaline
to adrenergic receptors (adrenal receptors)
the effect of parasympathetic stimulation on the SA node?
decrease
What 2 effects does the parasympathetic system effect the pacemaker cells?
1) hyperpolarisation of the SA node membrane potential (takes longer to reach threshold)
2) Decreases the rate of spontaneous depolarisation
What does ACh increase permeability to?
increase K+ permeability by slowing closure of channels
What effect does parasympathetic stimulation have on the AV node?
decreases excitability which prolongs prolongs
How does sympathetic increase HR?
speed up depolarisation, threshold reached more rapidly
How does NorAd speed up depolarisation?
arguments If and T-type channel activity
What hormone is released in the sympathetic system?
adrenaline
What is the collective term for adrenaline and noradrenaline?
catecholamines
What action of catecholamines increases heart rate?
chronotropic action
What action of catecholamines increases contraction?
inotropic action
