drydecay-
Two pumps
Oxygenated (pink/red) Deoxygenated (blue)
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The human heart has four chambers
Two thin-walled atria on top, which receive blood. Two thick-walled ventricles underneath which pump blood.
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Vein direction
Carry blood into the atria
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Atria direction
Carry blood away from the ventricles
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Blood vessels
Superior vena cava, inferior vena cava, left pulmonary veins, left pulmonary artery and aorta
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Parts of the heart
Right atrium, right ventricle, septum, left ventricle and left atrium
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Valves
Right atrio-ventricular valve (tricuspid), Chordae tendineae (cords), Left atrio-ventricular (bicuspid), semi-lunar valves
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Structure of arteries
Thick tunica externa (collagen) to resist high pressure, tunica media allows elastic recoil and aids propulsion of blood, small lumen diameter to favour high pressure and no valves
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Structure of veins/venules
Thin tunica media/externa and large lumen. No need of high pressure. Valves to prevent back flow and veins carry blood towards the heart under low pressure
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Structure of capillaries
No muscle, no elastic, no valves and one thin layer of cells (endothelium layer) only
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Structure of Arterioles
Similar to in structure to arteries but have more muscles. They constrict and dilate to control the flow of blood to capillaries
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Myogenic contraction
The heartbeat is initiated within the muscles themselves. They are not dependent on nervous or hormonal stimulation.
