A2 Biology Unit 5 Keywords

• SAN is a distinct group of cells found in the right atrium
• SAN is known as the pacemaker of the heart because it initiates a heartbeat as well as determines heart rate
• SAN is said to be myogenic, meaning it can cause the heart muscle to contract and relax without recieving nerve signals from neurones.
• SAN set up a wave of electrical excitation causing myocytes in the atrium to depolarise and contract
• The activity of the SAN can be changed by nerve impulses from the medulla oblongata

• The heart is said to be myogenic.
• This means it can stimulate the myocytes to contract and relax without an external stimuli/stimulus comes from within the heart.
• The result of stimulation results in myocytes becoming depolarised

A device that measures the electrical activity of the heart.

Redistribution of ions across the cell membrane causing {change in / different} potential difference / return to resting potential.

A test taken while someone excerising