Option D.4

Cardiac muscle cells are…

Cardiac muscle cells are…

Striated

Systole

Contraction of the heart’s chambers

Diastole

Relaxation of heart chambers

Sinoatrial node

Also known as pacemaker of the heart

Signal from the SA node reaches the…

Atrioventricular (AV) node

Signal from SA to AV node spreads throughout the heart via…

Purkinje fibers

Purkinje Fibres

Specialized heart muscle tissue

Ventricles begin diastole…

The AV valves open and ventricles start filling with blood

AV node cells have a smaller or bigger diameter?

Smaller diameter

Normal heart sounds are caused by the atrioventricular valves and semilunar valves…

Closing causing changes in blood flow

‘lub’ sound

When AV valves snap shut

‘dub’ sound

Semilunar valves close

Variables that can influence heart rate:

exercise, recovery from exercise, relaxation, breath holding, etc.

Artificial pace makers

Inserted into patients with a malfunctioning Sinoatrial node (part that initiates heartbeat)

Purpose of pacemaker

Maintain the rhythmic nature of the heart beat when the heart doesn’t beat fast enough or when there’s a fault in the heart’s electrical conduction system

Atherosclerosis

Hardening of arteries caused by the formation of plaques, or atheroma, on the inner lining of arteries