4 Autonomic Control of the CVS Flashcards
What nerve is responsible for parasympathetic control of the heart?
Vagus - CNX
Where does the Vagus nerve synapse with the heart?
Epicardial surface or within the walls of the heart at the SA and AV node
What neurotransmitter does the vagus nerve release?
ACh
What neurotransmitter acts on M2 receptors and what is the result?
ACh, decrease heart rate and decreased AV node conduction velocity
What nerve is responsible for sympathetic input to the heart?
Postganglionic fibres of the sympathetic trunk, the cardiac nerve
What does the cardiac nerve innervate?
SA node, AV node, myocardium
What receptor does it act on mainly?
beta 1 adrenoreceptors
What do beta 1 adreno receptor do?
Increase heart rate and increase force of contraction
Label the SA node action potential?
cool
What are the names of the channels that set up the funny current?
Hyperpolarization-activated cyclic nucleotide gated channels
What is the affect of increased sympathetic activity on the funny current?
Increased slope
What is the affect parasympathetic activity on the funny current?
Decreased slope
Explain why the sympathetic activity increases the slope?
- released NA
- acts on the Beta1 receptor
- causes an increase in the cAMP
- leads to more HCN channels being open
- speeds up depolarization
How does NA increase the force of contraction?
NA–>beta1–>increase cAMP–>PKA–> phosphorylation of the calcium channels, leading to increased calcium entry, more calcium, more contraction
What adrenoreceptors are found on blood vessels?
- most arteries and veins have alpa1-adrenoreceptors
- coronary and skeletal muscle vasculature also have beta2 receptors
