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Structure of heart
- 2. HEART •The heart is a roughly cone-shaped hollow muscular organ. • That is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions. •The term cardiac means "related to the heart" and comes from the Greek word, kardia, for "heart".
- 4. CONTI.. •The human heart is about the size of a fist and has a mass of between 250 and 300 grams. •It is about 10 cm long •It is located slightly left of middle in the chest, anterior to the vertebral column and posterior to the sternum.
- 5. POSITION OF HEART •The heart situated in thoracic cavity in mediasternum, the space between the lungs. •It lies little more to the left than the right, and have base above and an apex below.
- 6. CONTI.. •The apex is about 9 cm to the left of the midline at the level of the 5th intercostal space, little below the nipple and slightly nearer the midline. •The base extends to the level of the 2nd rib.
- 7. ORGANS ASSOCIATED WITH THE HEART •Inferiorly: Central tendon of the diaphragm. •Superiorly: The great blood vessels; aorta, superior venacava, pulmonary artery and vein. •Posteriorly: Oesophagus, trachea, bronchus, descending aorta.
- 8. CONTI.. •Laterally: The lungs •Anteriorly: The sternum, ribs and intercostal muscle.
- 9. STRUCTURE OF THE HEART The heart is composed of three layers of tissue 1.Pericardium 2.Myocardium 3.Endocardium
- 10. PERICARDIUM: •The pericardium is a triple-layered fluid- filled sac that surrounds the heart. •The outer layer of this sac is the fibrous pericardium. •It is a strong layer of connective tissue. •It adheres to the diaphragm inferiorly, and superiorly it is fused to the roots of the great vessels that leave and enter the heart.
- 12. CONTI.. •The fibrous pericardium acts as a tough outer coat that holds the heart in place and keeps it from overfilling with blood. •Deep to the fibrous pericardium is the double layered serous pericardium. •The serous pericardium is a closed sac sandwiched between the fibrous pericardium and the heart.
- 13. CONTI.. •The outer layer is the parietal layer of the serous pericardium and adheres to the inner surface of the fibrous pericardium. •The parietal layer is continuous with the visceral layer of the serous pericardium, which lies on the heart and is considered a part of the heart wall.
- 15. MYOCARDIUM •The myocardium is the basic muscle that makes up the heart. •This muscle is involuntary. •The cardiac muscle structure consists of basic units of cardiac muscle cells known as myocytes. Coordinated contraction of the cardiac muscles is what makes the heart propel blood to various parts of the body.
- 16. CONTI.. •It is the function of the coronary arteries to supply blood and oxygen to the cardiac muscles. •This is the thickest of all the layers of the heart. •The cardiac muscles cannot afford to rest even for a single second.
- 17. CONTI.. •It is absolutely essential that these muscles get blood supply and nutrition continuously, as any kind of disruption in the blood and nutrition supply to these muscles can result in death of a part of the cardiac muscle, which is known as myocardial infarction or heart attack. •This could in turn lead to a complete cessation of functioning of the heart muscles, known as cardiac arrest.
- 18. ENDOCARDIUM •The endocarium is the innermost, thin and smooth layer of epithelial tissue that lines the inner surface of all the heart chambers and valves. •This layer is made of thin and flat cells that are in direct contact with the blood that flows in and out of the heart.
- 19. CONTI.. •Each heart valve is formed by a fold of endocardium with connective tissue between the two layers. •However, rather than just being an inner lining of the heart, the endocardium also has an endocrine function.
- 20. CONTI.. •This is one of the only layers of the heart that has a single cell lining that secretes the hormone endocardin, which is responsible for prolonging myocardial contraction.
- 22. CHAMBERS OF HEART The heart is a hollow organ divided into four chambers: 1. Right atrium 2. Right ventricle 3. Left atrium 4. Left ventricle
- 25. RIGHT ATRIUM •The right atrium is a broad, triangular structure. •The superior vena cava opens into dome of right atrium and the inferior vena cava into its lower posterior part. •The right atrium is a thin-walled chamber that receives the blood retuning from the body tissues.
- 26. CONTI.. •This blood, which is low in oxygen, is carried in the veins, the blood vessels leading to the heart from the body tissues.
- 27. RIGHT VENTRICLE •The right ventricle extends from the right atrioventricular (tricuspid) orifice nearly to the cardiac apex. •It then reaching the pulmonary orifice and supporting the cusps of the pulmonary valve.
- 28. CONTI.. •The ventricle possesses an inlet component which supports and surrounds the tricuspid valve. •The right ventricle pumps the venous blood received from the right atrium and sends it to the lungs.
- 29. LEFT ATRIUM •Although smaller in volume than the right, the left atrium has thicker walls (3 mm on average). •Its cavity and walls are formed largely by the proximal parts of the pulmonary veins. •The left atrium receives blood high in oxygen content as it returns from the lungs.
- 30. LEFT VENTRICLE •The left ventricle is constructed in accordance with its role as a powerful pump •Its cavity is oval or nearly circular, with walls about three times thicker (8–12 mm) than those of the right ventricle.
- 31. CONTI.. •The left ventricle, which has the thickest walls of all, pumps, oxygenated blood to all parts of the body. •This blood goes through the arteries, the vessels that take blood from the heart to the tissues
- 32. VALVES OF HEART •The ventricles are the pumping chambers, the valves, which are all one way, are located at the entrance and the exit of each ventricle. •The entrances valves are the atrioventricular valves, while the exit valves are the semilunar valves. Semilunar means “resembling a half moon.”
- 33. CONTI.. •The two Atrioventricular (AV) valves , which are between the atria and the ventricles; I. Mitral valve II. Tricuspid valve •The two Semilunar (SL) valves, which are in the arteries leaving the heart. I. Aortic valve
- 35. MIRTAL VALVE •The left atrioventricular valve is the bicuspid valve, but it is usually referred to as the mirtal valve. •It has two rather heavy cusps that permit blood to flow freely from the left atrium into the left ventricle. •Both the tricuspid and mitral valves are attached by means of thin fibrous threads to the wall of the ventricles.
- 36. CONTI.. •The tricuspid valve is the three-flapped valve on the right side of the heart, between the right atrium and the right ventricle which stops the backflow of blood between the two. •It has three cusps.
- 37. TRICUSPID VALVE •The right atrioventricular valve also is known as the tricuspid valve, since it has three cusps, or flaps, that open and closes. •When this valve is open, blood flows freely from the right atrium into the right ventricle. •However, when the right ventricle begins to contract, the valve closes so that blood cannot return to the right atrium.
- 38. AORTIC (SEMILUNAR) VALVE •The aortic (semilunar) valve is located between the left ventricle and the aorta. •Following contraction of the left ventricle, the aortic valve closes to prevent the flow of blood back from the aorta to the ventricle.
- 39. PULMONIC (SEMILUNAR) VALVE •The pulmonic (semilunar) valve is located between the right ventricle and the pulmonary artery that leads to the lungs. •As soon as the right ventricle has finished emptying itself, the valve closes in order to prevent blood on its way to the lungs from returning to the ventricle.
- 40. BLOOD SUPPLY TO THE HEART •Arterial supply: The right & left coronary arteries supply blood to the heart. These are the branches arise from the aorta. The coronary artery further divided to from a network of capillaries. •Venous return: Most of the blood is collected into several small veins. These join to form the coronary sinus. The coronary sinus opens into the right
- 41. BLOOD CIRCULATION THROUGH THE HEART •The heart is a large muscular organ which constantly pushes oxygen-rich blood to the brain and extremities and transports oxygen-poor blood from the brain and extremities to the lungs to gain oxygen.
- 42. CONTI.. •Blood flow from superior & inferior vena cava to Right atrium. •From the right atrium blood moves into the right ventricle through the tricuspid valve and is pushed into the pulmonary arteries (Deoxygenated blood) in the lungs. •Where the blood get purified and process of exchange of gasses takes
- 43. CONTI.. •After picking up oxygen, the blood travels back to the heart through the pulmonary veins (oxygenated blood) into the left atrium. •From the left atrium through the bicuspid valve blood moves to the left ventricle. •From the left ventricle oxygenated blood goes to Aorta where the blood circulate to the rest of the body parts.