The cardiac cycle

The cardiac cycle: The cradiac cycle is a sequence of events in one heartbeat

Sequence of contraction

Filling phase

• Both atria & ventricles are relaxing
• Internal volume increases & blood flows into heart from the major veins
• Blood flows into atria- then through open atrioventicular valves & into ventricles
• This phase is called diastole

Atrial contraction

• Heart beat starts when atria contract- left & right contract together
• small increase in pressure (from contraction)- helps…