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The name of the nerve is vagus nerve. It is the tenth cranial nerve. It comes all the way from skull to supply the organs from thorax and most from the abdomen also. It is purely parasympathetic nerve.
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What causes the pacemaker to change the rate at which the heart beats?
The sympatetic nerve increases the SA node to speed up the heart rate The parasympathetic nerve uses the vagus nerve which decreases HR
What causes the heart's pacemaker to change the rate at which the heart beats?
Nerves The sympatetic nerve increases the SA node to speed up the heart rate The parasympathetic nerve uses the vagus nerve which decreases HR
What is the cardiac effect of a drug that blocks parasympathetic activity?
Increased firing of the sinoatrial node (SA) and conduction through the atrioventricular node (AV) of the heart, because the actions of the vagus nerve are opposed/blocked.
Is the atrioventricular node starts each heart beat and is often called the pacemaker of the heart for that reason?
No, the sino-atrial node is the pacemaker of the heart. It receives signals from the heart centre in the medulla oblingata via either the parasympathetic nerve or sympathetic nerve. It the sends a signal to the right- and left artrium and then to the atrioventricular node which stimulates the right- and left ventricles to contract
The correct sequence in the conduction system of the heart is?
SA node, Internodal pathways, AV node, Bundle of His, Bundle branches, Purkinje fibers.
Does the sino-atrial node recieve both sympathetic and parasympathetic innervation?
Yes.
What is Saltatory conduction made possible by?
Saltatory conduction is made possible by myelinated nerve fibers. This is the means through which one node of Ranvier will communicate with the next.
What pickup the signal after the sinoatrial node?
Electricity fires from the SA node to the AV node. It then goes to the bundle of his and out the perkinji fibers.
Describe how the nerve impulse travels in the heart?
The brain can influence the heart in two ways. Sympathetic and parasympathetic stimulation. Parasympathetic stimulation of the heart is through the vagus nerve. Sympathetic stimulation of the heart is via cervical and thoracic splanchnic nerves. The heart has its own pacemaker cells, so the brain only changes the rate and contractility of the heart.
What nerve initiates the SA node to initiate an impulse?
vagus nerve
What do node cells of the heart depolarize?
purkinje fibers
6 Explain why the SA node generates action potentials at a frequency of approximately 100 beats per minute even though the average resting heart rate is 70 beats per minute?
This is because parasympathetic nerve innervation synapsing in the SA node reduces heart rate from 100bpm to 70bpm as its basal tone
