nervouse system

Question 1

describe how a heartbeat is initiated and coordinated

Answer 1

action potential is initiated by the SAN which causes a wave of electrical impulses causing atrial contraction. non conducting tissue prevents immediate contraction of ventricles. AVN delays impulse while ventricles fill. AV node triggers a wave of electrical activity down the bundle of his to the purkyne fibres. ventricles contract from base up

Question 2

explain how a rise in blood pressure results in a decrease in the rate of heartbeat

Answer 2

baroreceptors send electrical impulses to the medulla. impulses via parasympathetic nerves to SAN. release acetylcholene which decreases impulses to AVN

Question 3

Describe how an impulse reaches the base of the ventricles of the heart from the sinoatrial node.

Answer 3

it spreads through the atria through cardiac muscle to the atriovetricular node then through bundle of his.