Structure and Function of the Heart
The heart is located on the left breastbone of your body, it is shaped like an upsidedown fist and sits ontop of the diaframatic muscle. The heart is made up of 4 chambers the two atria ( which collect the blood) and the two ventricles that pump the blood out of the heart. The tricuspid valve which controls blood flow through the right atrium and right ventricle and the bicuspid valve pumps blood through the left atrium into the left valve. When the left side of the heart contraccts the blood transports out of the aorta around the body, oxygenated. When the blood gets deoxygenated this means that it has collected waste products and therfore it transports to the right side of the heart back to the lungs where then, through respiration it will get oxygenated.
Blood is carried through five different types of blood vessels, arteries, arterioles, capillaries, venules and veins. Arteries have large blood vessels and thick muscular walls witch contract and relax to send the blood to all areas of the body. The aorta is one of the main artery, when this leaves the heart it splits up into smaller vessels, called the arterioles (meaning little arteries). The flexible wall allows vessels to expand and contract this helps push blood around the long arteries this process is called peristalsis, this is how the smooth muscle contracts. When the arteries and arterioles divide they eventually feed blood into the into smaller blood vessels called capillaries. These are mainly found in the muscles and because the cell is only one cell thick it allows oxygen and other nutrients to pass through (process called diffusion). The blood flows slowly through the capillaries and picks up carbon dioxide and lactic acid. The capillaries eventually go back into larger blood vessels (venules) which eventually become veins. Veins have to contract to take blood back to the heart, they contain non-return valves to prevent backflow and predominantly carry deoxygenated blood except the pulmonary vein that carried oxygenated blood to the heart from the lungs.