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Dr.Sisara Bandara Gunaherath MBBS CVS consists of: Heart Blood vessels heartarteries arterioles veinsvenules capillaries What is the function of CVS Circulate blood throughout entire body for ◦ ◦ ◦ ◦ Transport of oxygen to cells Transport of CO2 away from cells Transport of nutrients (glucose) to cells Movement of immune system components (cells, antibodies) ◦ Transport of endocrine gland secretions Heart The heart is a cone-shaped, muscular organ An adult human heart weighs between 200 and 425 grams (7 and 15 ounces) and is slightly larger than a fist. The heart is located between the lungs in the middle of the chest, behind and slightly to the left of the sternum and in front of the spine A double-layered membrane called the pericardium surrounds the heart like a sac. Layers of the heart wall Three layers of tissue form the heart wall. The outer layer of the heart wall is the epicardium, the middle layer is the myocardium, and the inner layer is the endocardium. Epicardium The epicardium is the outer layer of the wall of the heart. It is composed of connective tissue ( mainly Adipose Tissue) covered by epithelium. Coronary vessels and cardiac nerves The epicardium is also known as the visceral pericardium Provides an outer protective layer for the heart. Cardiac Muscle/Myocardium Intercalated Disc Myocardium is the muscular middle layer of the wall of the heart. It is composed of spontaneously contracting cardiac muscle fibers which allow the heart to contract. Stimulates heart contractions to pump blood from the ventricles and relaxes the heart to allow the artria to receive blood. Endocardium The endocardium is the inner layer of the heart. It consists of epithelial tissue and connective tissue. Lines the inner cavities of the heart, covers heart valves and is continuous with the inner lining of blood vessels. Purkinje fibers are located in the endocardium. They participate in the contraction of the heart muscle. Pericardium The pericardium is the fluid filled sac that surrounds the heart and the proximal ends of the aorta, vena cava, and the pulmonary artery. Pericardial Membranes The pericardium is divided into two layers: Fibrous Pericardium - the outer fibrous sac that covers the heart. Serous Pericaridum – The membranous covering on the outside The serous pericardium is divided in to Parietal Pericardium Visceral Pericardium Functions of Pericardium Keeps the heart contained in the chest cavity. Prevents the heart from over expanding when blood volume increases. Limits heart motion. Chambers of the heart The human heart has four chambers. The upper chambers are called the left and right atria, and the lower chambers are called the left and right ventricles. A wall of muscle called the septum separates the left and right atria and the left and right ventricles. The two atria are thin-walled chambers that receive blood from the veins: the right atrium receives deoxygenated blood from systemic veins, while the left atrium receives oxygenated blood from the pulmonary veins. The two ventricles are thick-walled chambers that forcefully pump blood out of the heart. Differences in thickness of the heart chamber walls are due to variations in the amount of myocardium present, which reflects the amount of force each chamber is required to generate. The left ventricle is the largest and strongest chamber Valves Valves are flap-like structures that allow blood to flow in one direction. The heart has two kinds of valves, atrioventricular and semilunar valves. Atrioventricular Valves The atrioventricular valves are thin structures that are composed of endocardium and connective tissue. They are located between the atria and the ventricles. Mitral Valve Tricuspid Valve Semilunar Valves The semilunar valves are flaps of endocardium and connective tissue reinforced by fibers which prevent the valves from turning inside out. They are shaped like a half moon, hence the name semilunar (semi-, -lunar). The semilunar valves are located between the aorta and the left ventricle and between the pulmonary artery and the right ventricle. Aortic Valve Pulmonary Valve Function of the Heart Right Side of the Heart The right side of the heart receives deoxygenated blood from the body tissues (from the upper- and lower-body via the Superior Vena Cava and the Inferior Vena Cava, respectively) into the right atrium. This de-oxygenated blood passes through the tricuspid valve into the right ventricle. This blood is then pumped under higher pressure from the right ventricle to the lungs via the pulmonary artery Left-Hand Side of the Heart The left-hand side of the heart receives oxygenated blood from the lungs (via the pulmonary veins) into the left atrium. This oxygenated blood then passes through the bicuspid valve into the left ventricle. It is then pumped to the aorta under greater pressure This higher pressure ensures that the oxygenated blood leaving the heart via the aorta is effectively delivered to other parts of the body via the vascular system of blood vessels (incl. arteries, arterioles, and capillaries).