Anatomy of the Cardiovascular System PDF - Al-Farahidi University

College of Pharmacy Al-Farahidi University Anatomy of the Cardiovascular system Human Anatomy for 1st-year Pharmacy Students 24-23 ‫ رائد ضياء هاشم‬.‫د‬.‫م‬.‫ا‬ Al-Farahidi University...

College of Pharmacy Al-Farahidi University Anatomy of the Cardiovascular system Human Anatomy for 1st-year Pharmacy Students 24-23 ‫ رائد ضياء هاشم‬.‫د‬.‫م‬.‫ا‬ Al-Farahidi University College of Pharmacy Human Anatomy for 1st year pharmacy students Anatomy of the Cardiovascular system Human anatomy is the study of the structure of the human body and the relationship between its parts. Anatomy goes back to the Greek roots ana, meaning "up," and temnein "to cut." The cardiovascular system is responsible for supplying the whole-body organs with blood to perform their function. Its function is regulated by various stimuli in order to control the amount and the pressure of blood reaching a certain organ. The circulatory system is composed of the cardiovascular system and the lymphatic system which is composed of lymphatic vessels in addition to the lymphoid tissues (spleen, lymph nodes, thymus). The cardiovascular system is composed of the following structures: 1- The heart 2- The arteries 3- The veins 4- The capillaries HEART The heart is a conical, hollow muscular organ, consisting of four chambers, covered by the pericardium situated within the middle mediastinum and acts as a central pumping organ of the cardiovascular system. It is connected at its base to the great blood vessels but otherwise lies free within the pericardium. (the Greek name for the heart is cardia). Mediastinum: It is the compartment of the chest that lies between For practical purposes, the heart may be the pleural sac of the lungs. It extends from the thoracic inlet to the upper surface considered to have both an apex and four of the diaphragm. borders. The apex, formed by the left ventricle, It contains many vital structures such as heart, great vessels, trachea, and essential nerves. corresponds to the apex beat and is found in the fifth left intercostal space 9 cm from the midline. The heart is considered as an enlarged, internally subdivided blood vessel specialized for pumping. Its major unique and dominant functional feature is a myocardial layer 1 Al-Farahidi University College of Pharmacy Human Anatomy for 1st year pharmacy students composed largely of cardiac muscle. About two-thirds of the heart lies to the left of the midline and one third to the right of the midline. The heart contains four chambers, two atria and two ventricles. The atria and ventricles are connected via atrioventricular valves. The atria receive venous blood, pump blood only to the immediately adjacent ventricles, and therefore are low-pressure chambers. The ventricles pump arterial blood out of the heart, must convey pulmonary and systemic pulses of blood, and therefore are comparatively high-pressure chambers. The ventricles are the major sources of energy for the circulation of blood. Surface markings of the heart The superior border Formed by the roots of the great blood vessels, extends from a point on the second left costal cartilage (1.3 cm) from the edge of the sternum to a point on the third right costal cartilage (1.3 cm) from the edge of the sternum. The right border Formed by the right atrium, extends from a point on the third right costal cartilage 0.5 in. (1.3 cm) from the edge of the sternum downward to a point on the sixth right costal cartilage (1.3 cm) from the edge of the sternum. The left border Formed by the left ventricle, extends from a point on the second left costal cartilage (1.3 cm) from the edge of the sternum to the apex beat of the heart. The inferior border Formed by the right ventricle and the apical part of the left ventricle, extends from the sixth right costal cartilage (1.3 cm) from the sternum to the apex beat. The apex beat can usually be seen and palpated in the living patient. The heart has two functional circuits, the right heart and the left heart. The right heart (right atrium and right ventricle) is the pulmonary circuit pump. In this, blood travels a relatively short distance to the lungs and back against low peripheral resistance. The left heart (left atrium and left ventricle) is the systemic circuit pump. Here, blood travels a long distance through the body against high peripheral resistance. 2 Al-Farahidi University College of Pharmacy Human Anatomy for 1st year pharmacy students The anterior surface of the heart The posterior surface of the heart 3 Al-Farahidi University College of Pharmacy Human Anatomy for 1st year pharmacy students The structure of the heart The heart wall has three layers, these are: the pericardium, the myocardium and the endocardium. 1- The visceral layer of the serous pericardium (epicardium) makes up the external layer. 2- The cardiac muscle (myocardium) is the primary constituent of the middle layer. 3- A layer of the endothelium (endocardium) lines the inner surface and forms the internal layer of the heart. The atrial portion of the heart has relatively thin walls, whereas the ventricular portion of the heart has thick walls. In addition, two internal septa divide the heart into its four chambers. The atrial (interatrial) septum separates the right and left atria. The ventricular (interventricular) septum separates the right and left ventricles. The ventricular septum has a lower, thicker muscular part and a smaller upper, thinner membranous part. Chambers of the heart 1- Right Atrium The right atrium received the deoxygenated blood from the whole body through: The superior vena cava which drains blood from the upper half of the body and has no valve. The inferior vena cava which drains blood from the lower half of the body (larger than the superior vena cava) which has a valve although it is non-functioning in adults. The coronary sinus which drains returning blood from the heart wall itself. 2- Right Ventricle Blood flows from the right atrium to the right ventricle through the right atrioventricular orifice. The pulmonary orifice allows blood to exit the ventricle and enter the pulmonary trunk. The walls of the right ventricle are much thicker than those of the right atrium and show many internal projecting ridges formed from muscle bundles. It has a triangular shape and comprises the majority of the heart's anterior surface. 4 Al-Farahidi University College of Pharmacy Human Anatomy for 1st year pharmacy students 3- Left Atrium The left atrium gets oxygenated blood from the four pulmonary veins and pumps it into the left ventricle through the left atrioventricular orifice (protected by the mitral valve). The left atrium forms the heart's posterior boundary (base) in its anatomical position. The left auricle protrudes from the chamber's superior wall, overhanging the pulmonary trunk's root. The four pulmonary veins, two from each lung, open through the posterior wall and have no valves. 4- Left ventricle The left ventricle collects oxygenated blood from the left atrium and pumps it into the aorta through the aortic orifice (which is protected by the aortic valve). The apex of the heart, as well as the left and diaphragmatic boundaries, are formed by the left ventricle in its anatomical location. It is separated into an inflow and outflow portion, similar to the right ventricle. The walls of the left ventricle are three times thicker than those of the right ventricle and the left intraventricular blood pressure is six times higher than that inside the right ventricle. Interventricular Septum The interventricular septum is made up of a superior membranous part and an inferior muscular part that connects the two ventricles. The muscular portion of the septum has the same thickness as the left ventricular wall and makes up the majority of the septum. The membranous component of the heart is thinner and forms part of the fibrous skeleton. Pericardium The pericardium is a fibrous sac that encloses the heart and great vessels. It consists of two layers: the fibrous (external) and the serous (internal). The pericardium has the following functions: 1- Fixation of the heart: The heart is fixed in the mediastinum and its mobility is limited. Because the pericardium is linked to the diaphragm, sternum, and the tunica adventitia (outside layer) of the major vessels, the heart can be fixed. 2- Preventing overfilling: The pericardium is a somewhat inextensible fibrous layer that stops the heart from becoming too large too quickly, putting a physical limit on the organ's maximum growth. 3- Lubrication: The friction caused by the heart as it moves through the thoracic cavity is reduced by a thin film of fluid between the two layers of the serous pericardium. 5 Al-Farahidi University College of Pharmacy Human Anatomy for 1st year pharmacy students 4- Preventing infection: The fibrous pericardium acts as a physical barrier between the heart's muscular body and infection-prone organs such as the lungs. Heart Arterial Supply The heart has a small margin for error in its physiology and function. Therefore, it requires a dense vascular system for the regulation of blood gases and nutrients. The right and left coronary arteries provide the arterial supply of the heart. These are the first branches of the aorta. They arise from the ascending aorta immediately above the aortic valve and initially pass around the opposite sides of the pulmonary trunk. The coronary arteries and their major branches are distributed over the surface of the heart and lie within subepicardial connective tissue. Cardiac valves The valves of the heart are structures that ensure blood flows in only one direction. The valves prevent regurgitation of the blood. Cardiac valves are composed of connective tissue and the endocardium (the inner layer of the heart). The heart's valves are found in two pairs: (a) A pair of atrioventricular valves, which transport blood from the atria to the ventricles. (b) A pair of semilunar valves that drain blood from the ventricles (the inner layer of the heart). Except for the mitral valve, which contains two leaflets, all of the valves are trileaflet. 6 Al-Farahidi University College of Pharmacy Human Anatomy for 1st year pharmacy students Mitral valve The left atrium and the left ventricle are connected by the mitral valve. During diastole, the mitral valve opens, allowing blood to pass from the left atrium to the left ventricle. The mitral valve closes during ventricular systole, preventing backflow to the left atrium. Because it contains two cusps, it's also known as the bicuspid valve (anterior and posterior). Like the tricuspid valve, the base of each cusp is anchored to a fibrous ring that surrounds the orifice. The mitral/bicuspid valve has two cusps: a larger anterior/aortic cusp and a smaller posterior cusp. Tricuspid valve The tricuspid valve (the right atrioventricular valve complex) is made up of the 3 valve leaflets, located between the right atrium and right ventricle. It functions similar to the bicuspid valve during systole and diastole. Aortic valve The aortic valve is located between the left ventricular outflow tract and the ascending aorta. The left and right aortic sinuses mark the origin of the left and right coronary arteries. When blood recoils during ventricular diastole, it fills the aortic sinuses and enters the coronary arteries to supply the myocardium. Pulmonary valve The semilunar valve that isolates the right ventricle from the pulmonary trunk is known as the pulmonary valve. It consists of three cusps; anterior, left, and right cusp. Large Thoracic Arteries The aorta and pulmonary trunk are the large arteries in the thorax. These two vessels give rise to all arterial flow in the thorax. The aorta provides the systemic circuit flow, and the pulmonary trunk provides the pulmonary circuit flow. 7 Al-Farahidi University College of Pharmacy Human Anatomy for 1st year pharmacy students Aorta The aorta is the main arterial trunk that delivers oxygenated blood from the left ventricle of the heart to the tissues of the body. It consists of four main parts: ascending aorta, arch of the aorta, descending thoracic aorta, and abdominal aorta Pulmonary Trunk The pulmonary trunk conveys deoxygenated blood from the right ventricle of the heart to the lungs. It leaves the infundibulum (upper part) of the right ventricle and runs upward, backward, and to the left. It is about 2-in. (5-cm) long and terminates in the concavity of the aortic arch by dividing into right and left pulmonary arteries. It lies in the middle mediastinum, together with the ascending aorta, enclosed in the fibrous pericardium and a sheath of the serous pericardium. 8