IB Biology HL C3.1.14 covers receptor feedback and medullary control of the sinoatrial node. Practise how sympathetic and parasympathetic signals raise or lower heart rate.
Outline how the rate at which the heart beats is controlled.
heart cells can contract on their own / myogenic (muscle contraction);
contractions/heart beat controlled by/starts at pacemaker/sinoatrial node;
pacemaker/sinoatrial node is in the wall of the right atrium;
signal to contract transmitted from across the atria/heart muscle/heart wall;
nerves/impulses from medulla (of brain) to heart;
one nerve increases rate and another nerve decreases it;
epinephrine/adrenalin increases rate;
Marking guidance:
[6 max] Reject noradrenalin.
Details of events in the cardiac cycle are not relevant and should not be rewarded
Do not award marks for reference to the autonomic, sympathetic or parasympathetic nervous systems as these are Option E topics.