The Cardiovascular System
The cardiovascular system is made up of the heart, blood vessels and the blood and its main functions include the transportation of blood around the body, protection from invading microorganisms and to prevent blood loss through haemostasis. (Widamaier, et al 2011:5)
One of the main organs of the cardiovascular system is the heart; the heart is made up of four chambers. The blood enters the right atrium of the heart from body through the venae cavae, it then travels though the tricuspid atrioventricular valve into the right ventricle. The blood is then pumped through the pulmonary semilunar valve out of the heart to the lungs using the pulmonary arteries. It is then ...view middle of the document...
The internal layer, called the endocardium, is a smooth squamous lining on the inside of the heart its function is to prevent blood sticking to the inside of the heart and causing clots. (Taylor 2013)
The heart is controlled by an electrical signal that originates from within the heart. The signal starts in the sinoatrial node, also known as the pacemaker, when the electrical signal is initiated the atria contract. It travels to the atrioventricular node which delays the signal to allow time for atrial systole. It travels down the bundle of his where it then splits into the left and right bundle branches then to the purkinje fibres which cause the ventricles to contact. This electrical signal controls the cardiac cycle. The heart beats starts with atrial systole in this phase the atria contact forcing blood into the ventricles. Atrial systole ends and atrial diastole begins where the atria relax. Ventricular systole first phase begins the ventricles contract, pressure increases forcing the atrioventricular valves shut. The second phase begins pressure opens the semilunar valves open pushing the blood into the blood vessels. Ventricular systole ends and ventricular systole begins, in early ventricular diastole the pressure drops in the ventricles and the semilunar valves close. In late ventricular diastole all chambers relax, the atrioventricular valves open and the blood fills the heart to begin a new cycle. (Moran, No Date)
The heart has its own blood supply to keep it alive. The blood enters the myocardium of the heart through coronary arteries. Both coronary arteries start from the aorta just above the aortic valve. The left originates from the left aortal sinus and the right from the right aortal sinus. The coronary arteries then run on the surface of the heart these are called epicardial arteries. The epicardial arteries can be affected from atherosclerosis. Atherosclerosis is a condition where fatty deposits clog the arteries blocking the artery or creating a greater chance for a clot blocking the artery. When the coronary arteries run deep into the heart they are referred to as subendocardial arteries. The blood then returns from the heart muscle through cardial veins to the right atrium. (Fuster, Alexander, O'Rourke 2001:53)
Another circuit of the circulatory system is pulmonary circulation. Pulmonary circulation Is where the blood leaves the heart to be oxygenated by the lungs and to release carbon dioxide and travels back to the heart to be pumped around the body. Deoxygenated blood leaves the heart from the right ventricle through the pulmonary artery. It then enters the pulmonary capillaries where gaseous exchange happens between the capillaries and the alveoli. The blood, now oxygenated, returns through the heart in the pulmonary vein back into left atrium of the heart. The oxygenated blood leaves the left ventricle of the heart to and around the body, this is called systemic circulation. In systemic circulation blood travels...