Lecture 8 -control And Regulation Of Contraction Flashcards
How do you measure strength?
You look at the volume of blood that is ejected
What does the sympathetic nervous system do to the heart?
Increases heart rate as it innervates the nodes of the cell
What do the right sympathetic nerves do?
Innervates the SA node and causes the heart rate to go up
What is a positive chronotropic affect?
Increase in heart rate
What do the left side of the sympathetic nerves do?
Innervates the ventricular muscle which increases the stroke volume (increasing contractility)
What does the parasympathetic nervous system do to the heart?
Decreases heart rate
What does the right side of the parasympathetic nerves do?
Innervates the SA node
What does the left side parasympathetic nerves do?
Innervates the AV node
Can parasympathetic innervation happen in the ventricular muscle?
No only in the nodal tissues
What is a negative chronotropic affect?
Decrease in heart rate
What type of receptors do sympathetic nerve cells have?
Beta 1 receptors
What does sympathetic stimulation do to the regulation of heart rate?
Depolarises the SA node and increases the rate of depolarisation - depolarises the pacemaker of the cell
What happens when the rate of depolarisation increases?
Calcium channels are opened quicker as you have reached the threshold more quickly - more action potentials
What receptors are involved in the parasympathetic regulation of heart rate? And what is the neurotransmitter involved?
M2 muscarinic receptors and acetylcholine
What does parasympathetic stimulation do to the SA node (pacemaker)?
Hyperpolarises the cell and slows the heart rate - membrane potential becomes more negative
What happens when there is a slower depolarisation?
Means it takes longer to reach the threshold so the calcium channels don’t open as quick which decreases the heart rate
What drug blocks the muscarinic receptors?
Atropine
What does Adenylyl cyclase reduce?
Cyclic AMP and produces PKA