Chapter 16 Notes
The heart lies in the mediastinum and is surrounded by a doubled layered membrane called the pericardium. The outer most layer of the pericardium is called the fibrous pericardium, which anchors the heart to surrounding structures. The inner layer is called the serous pericardium and is composed of two layers. The outer portion is called the parietal pericardium, the inner portion is called the visceral pericardium (epicardium). Epicardium- outer most layer of the heart wall
Myocardium- The actual muscle of the heart.
Endocardium- innermost layer of the heart.
The heart consists of four hollow chambers two atria that receive blood from the body’s veins. And two ventricles that pump blood into the body’s arteries. There is a thin wall between the atria’s that is called the interatrial septum. There is a wall between the ventricles called interventricular septum. Right Atrium- This is the superior right chamber. It receives deoxygenated blood from the main veins, the superior and inferior vena cava and the coronary sinus. (These veins drain a series of blood vessels called the systemic circuit in which gases and nutrients are exchanged between the blood and the tissue cells) Right Ventricle- Inferior to the right atrium and it receives deoxygenated blood and ejects it into the pulmonary trunk or pulmonary artery. (Pulmonary trunk branches into right and left pulmonary arteries, which deliver deoxygenated blood to the lungs through a series of vessels called the pulmonary circuit). This is where the blood becomes oxygenated. Left Atrium- Superior left chamber that receives oxygenated blood returning from the pulmonary circuit through the pulmonary veins (exception). Left Ventricle- receives oxygenated blood from the left atrium and pumps it into the largest artery in the systemic circuit called the aorta. The aorta then branches off to deliver the oxygenated blood to the body’s cells. The left ventricle is much thicker than the right ventricle because the pressure is much thicker in the systemic circuit than in the pulmonary circuit. There are valves in-between the chambers of the heart and ventricles. These valves prevent the blood from flowing backwards into the heart. The valves between the chambers are called the atrioventricular valves. The tricuspid valve is between the right atrium and the right ventricle. The bicuspid valve (mitral) is located between the left atrium and the left ventricle. Each valve is attached to collagenous strings called chordae tendineae and attached to muscles within the ventricular wall called papillary muscles. The valves between the ventricles and their arteries are called the semilunar valves. The pulmonary valve lies between the right ventricle and the pulmonary trunk. The aortic valve lies between the left ventricle and the aorta. The coronary arteries branch off the base of the aorta and bring oxygenated blood to the cells of the myocardium and they are drained by a set of cardiac veins. The right coronary artery travels in the right coronary sulcus and branches into the marginal artery, which serves the lateral part of the right atrium and right ventricle and the posterior interventricular artery, which serves the posterior heart. The left coronary artery, which branches and forms into the anterior interventricular artery, which supplies the anterior heart and the circumflex artery, which supplies the left atrium and posterior left ventricle. Myocardial Infraction- when a coronary artery is blocked, the reduced blood flow to the myocardium can cause hypoxic injury and result in tissue death. 1.) Small Cardiac Vein- drains the inferolateral heart.
2.) Middle Cardiac Vein- drains the posterior heart.
3.) Great Cardiac Vein- drains most of the left side of the heart. Coronary Sinus- located on the posterior right atrium and drains into the right atrium. Cardiac Monocytes- shorter, wider, and branched and are typically uninucleated. The nucleus is...
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