Human Transport System Essay Example | Topics and Well Written Essays - 1500 words

Human Transport System - Essay Example The atria and ventricle are separated by auricoventricular septum with a aperture guarded by three flaps called as tricuspid valve which prevents back flow of blood from right ventricle to right atria when right ventricle contracts. The opening of pulmary artery is also guarded by semi lunar valves to prevent the back flow of blood from pulmonary artery to right ventricle when it contracts. Thus right side of the heart receives venous blood from all parts of the body and pumps it to lungs for oxygenation. The left side of the heart also comprises of two chambers iii) upper left thin walled atria which receives oxygenated blood from the lungs through pulmonary veins and pumps to iv) lower left ventricle in turn opens to aorta to distribute to all parts of the body. Here again the atrioventricular septum separates upper and lower left atria and the ventricle with an aperture guarded by two flaps called the 'bicuspid valve' and the opening of aorta is guarded by 'aortic valve'. The superior vena cava collecting the deoxygenated blood from upper torso and head and Inferior venacava collecting from the lower torso and legs feeds the right atrium. The right atrium on contraction pours to right ventricle. The right chambers are small compared to left chambers as they carry blood to lungs of about a short distance. From the right ventricle pulmonary artery carries the deoxygenated blood to lungs for reoxygenation. After reoxygenation from lungs the blood is carried through pulmonary vein to left atrium which on contraction pumps to left ventricle. When the left ventricle if full the left atrium contracts pumping the blood in the left ventricle into the aorta which then distributes to entire body by means of small arteries arterioles and capillaries. Types of circulation I) Coronary circulation: Coronary circulation is the circulation of blood through the tissues of the heart for its own nourishment. The two coronary arteries branch from aorta and further branch themselves into smaller arteries capable enough to penetrate the cardiac muscles. II) Pulmonary circulation: The deoxygenated blood in right atrium is pumped to right ventricle and from there to lungs for reoxygenation and back from lungs to left atrium and subsequently to left ventricle is known as pulmonary circulation. III) Systemic circulation: the reoxygenated blood collected from lungs leaves the heart through the main artery-aorta. Aorta supplies the reoxygenated blood to all parts of the body through network of smaller arteries and capillaries. Again after the exchange of oxygen and metabolites it is collected from the capillaries of venous system and directed to the right atrium through two vena cavae. This phase is systemic circulation. During systemic circulation blood passes through kidneys for waste removal known as 'renal circulation' phase and also through small intestine known and 'portal circulation' phase. Structure and functions of the blood vessels Anatomically all blood vessels are made up of three layers i) inner -tunica intima. It is made up of flat endothelial cells resting on a layer of connective tissue with