CV system - Heart and cardiovascular system The heart an...

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Heart and cardiovascular system The heart – an amazing organ! Beats constantly, never rests, about 100,000x per day and circulates 8000 L blood/day… a big job… but necessary so that all the cells of the body will have access to nutrients and O2, and a way to get rid of waste. Organization of the CV system – basically 2 loops, one small (pulmonary) and one large (systemic), both of which begin and end at the heart. Blood LEAVING the heart travels in arteries Blood ARRIVING AT the heart travels in veins… this is regardless of the O 2 content of the blood. Capillaries aka exchange vessels, where nutrient/gas exchange takes place. Heart: contains 4 chambers, 2 atria and 2 ventricles, R and L. From body blood enters R atrium, goes to R ventricle, and is pumped into pulmonary circuit (lungs); enters L atrium from lungs, enters L ventricle, and is pumped into systemic circuit. Atria: relatively thin muscular walls, highly expandable. Ventricles, more muscular Right atrium (RA): Receives blood from systemic circuit through vena cavae –superior, from head, neck, upper limbs, and chest; inferior, from the rest of the body. Cardiac veins also return blood to RA. Right ventricle (RV): Blood leaves RA and travels through the right AV valve, aka the tricuspid valve. The three flaps of the AV valve are attached to chordae tendinae, which originate at the papillary muscles on the inner surface of the right ventricle. The AV valve closes when the ventricle contracts, keeping blood from backing up into the atrium. The chordae tendinae keep the flaps from just flapping all the way open the other direction. Pulmonary semilunar valve – similar to AV valve, valve at entrance to pulmonary trunk (artery that goes to lungs from RV). R and L pulmonary arteries go to R and L lungs. Left atrium (LA): L and R pulmonary veins bring oxygenated blood from lungs. Left AV valve, aka bicuspid valve or mitral valve is between LA and LV. Left ventricle (LV): Much larger than RV, has very thick muscular walls. This allows LV to push blood with a lot of force into the systemic circulation… this requires a lot more force than sending blood to pulmonary circulation. Blood leaves through aortic valve, aka aortic semilunar valve, and goes into ascending aorta. R and L coronary arteries branch off from this, and then aortic arch and descending aorta. Coronary circulation: supplies blood to the heart, as the tissue of the heart is highly metabolically active and requires a lot of O 2 ! The heartbeat:
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CV system - Heart and cardiovascular system The heart an...

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