1. Learning Objectives...
To understand the stages of the cardiac cycle.
To be able to label the different parts of the heart.

2. Heart pictures and information

3. The Heart
The heart is a double pump – two separate pumps that work side by side
The right side pumps deoxygenated blood to the lungs
The left side pumps oxygenated blood to the rest of the body
The heart consists of four chambers –two upper atria and two lower ventricles
The atrio- ventricular valves separate the atria and ventricles
The semi-lunar valves are found in the pulmonary artery and aorta.

4. The cardiac cycle How blood flows through the heart
Two phases systole – contraction phase (atrial and ventricular) – 0.3 secs diastole – relaxation phase – 0.5 secs
DIASTOLE
atria fill with blood
pressure rises
atrioventricular valves open
blood passes by gravity into ventricles
semi lunar valves closed
SYSTOLE
Atrial systole
Atria contract
Forces remaining blood into ventricles
Ventricles remain relaxed
Ventricular systole
Ventricles contract at same time
Blood pressure increases
AV valves forced shut (so no backflow)
Semi-lunar valves forced open
Blood pushed into aorta and pulmonary artery

5. Part I Cardiovascular system
Briefly describe, in order, the events during the cardiac cycle in the diagrams below.
1. Diastole………………………………………
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2. Atrial Systole…………………….………
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…………………………………………………………
3. Ventricular Systole……………………
………………………………………………………..
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