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The heart - Coggle Diagram
The heart
The circulatory system
- The heart pumps blood through blood vessels (arteries, veins and capillaries)
- There are two circuits, one circuit takes blood around the body and another one takes blood to the lungs
- Arteries carry blood from the heart to the rest of the body, have elastic tissue to stretch and recoil as the heart beats, which helps maintain the high pressure.
- The inner lining (endothelium) is folded allowing the artery to stretch.
- All arteries carry oxygenated blood except for the pulmonary arteries, which takes deoxygenated blood to the lungs
- Arteries divide into arterioles, blood is directed to different areas in the body by muscles inside the arterioles, which contract to restrict the blood flow or relax to allow full blood flow.
- veins take blood back to the heart under low pressure. They do contain valves and blood flow is helped by the contraction
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The cardiac cycle
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Diastole (relaxation)
- pressure in the ventricles is lower than the pressure in the arteries so the semi lunar vales close
- All valves in heart close
- Atria and ventricles relax
- Blood fills the atria again from the veins
Valves
- Made up of flaps of tough, flexible, fibrous tissue
- When pressure is greater on the convex side of the cusps, they move apart to let blood pass between cusps
- When pressure is greater on the concave side , blood collects within the 'bowl' of the cusps, this causes them together to form a tight fit which prevents the passage of blood
The right side pumps deoxygenated blood to the lungs and the left side pumps blood to the whole body
- The left ventricle of the heart has thicker more muscular walls than the right ventricle (it needs to contract more powerful to pump blood all around the body)
- The ventricles have thicker walls than the atria because atria only have to push blood into the ventricles, not the entire body
- The atrioventricular (AV) valves link the atria to the ventricles and prevent blood from flowing backwards into the atria when the ventricles contract.