CVS: Autonomic Control Of The CVS Flashcards
Where does the parasympathetic system originate?
Cervical sacral sections
Where does the sympathetic system originate?
Lumbar-Thoracic regions
What neurotransmitters are released in the parasympathetic system?
ACh
What neurotransmitters are released in the sympathetic nervous system?
Noradrenaline/adrenaline
Where does the parasympathetic system innovate the heart?
SA and AV node
Where does the sympathetic system innovate the heart?
SA, AV and myocardium
How does the sympathetic system effect pacemaker potentials?
Act on beta-1 receptors. Gs protein coupled receptors stimulate the production of adenyl Cyclase which stimulates an increase in cAMP. This directly affects HCN receptors making the depolarisation occur faster and hence speeding you the pacemaker potential.
How does the parasympathetic system effect pacemaker potentials?
It slows the rate of depolarisation.
Mediated by M2 G-protein coupled receptors. Increases potassium conductance and decreases cAMP (therefore decreasing the activity of HCN channels)
How does noradrenaline increase the force of contraction?
- NA acting on B1 receptors in myocardium causes an increase in cAMP which activates PKA.
- Phosphorylation of calcium channels increasing calcium influx
- Increased uptake of calcium into SR
- Increased sensitivity of contractile machinery to calcium
Do most vessels receive sympathetic or parasympathetic innervation?
Sympathetic
Does circulating adrenaline have a higher affinity for B2 or A1 receptors?
B2
TRUE OR FALSE: at higher concentrations, adrenaline will also activate A1 receptors?
True
What does activating B2 receptors cause?
Vasodilation
What does activating A1 receptors cause?
Vasoconstriction
True or false: Metabolites are more important for ensuring adequate perfusion of skeletal and coronary muscle than activation of β2-receptors.
True
