HSF 2 Test 2 PDF

HSF 2 test 2 The heart 1. Describe the size, shape, location, and orientation of the heart in the thorax. 2. Name the coverings of the heart. 3. Describe the structure and function of each of the three layers of the heart wall 4. Describe the structure and functions of the four heart chambers. Name...

HSF 2 test 2 The heart 1. Describe the size, shape, location, and orientation of the heart in the thorax. 2. Name the coverings of the heart. 3. Describe the structure and function of each of the three layers of the heart wall 4. Describe the structure and functions of the four heart chambers. Name each chamber and provide the name and general route of its associated great vessel(s). 5. Name the heart valves and describe their location, function, and mechanism of operation 6. Trace the pathway of blood through the heart. 7. Name the major branches and describe the distribution of the coronary arteries. 8. Describe the structural and functional properties of cardiac muscle, and explain how it differs from skeletal muscle. 9. Briefly describe the events of excitation-contraction coupling in cardiac muscle cells. 10. Describe and compare action potentials in cardiac pacemaker and contractile cells. 11. Name the components of the conduction system of the heart, and trace the conduction pathway. 12. Draw a diagram of a normal electrocardiogram tracing. Name the individual waves and intervals, and indicate what each represents. Name some abnormalities that can be detected on an ECG tracing.” 13. Describe the timing and events of the cardiac cycle. 14. Describe normal heart sounds, and explain how heart murmurs differ. 15. Name and explain the effects of various factors regulating stroke volume and heart rate. 16. Explain the role of the autonomic nervous system in regulating cardiac output. The heart (answers) 1. The heart's size varies among individuals but is generally comparable to a closed fist. Its shape is asymmetrical, with the apex forming a pointed tip while the base is broader. Located within the mediastinum, a central compartment in the chest, the heart is positioned posterior to the sternum, medial to the lungs, and anterior to the vertebral column. Its orientation leans slightly to the left, creating a distinct border known as the cardiac notch on the left lung. 2. The fibrous pericardium serves as a protective outer layer, anchoring the heart in place and preventing overstretching. The serous pericardium further comprises the parietal layer, lining the fibrous pericardium, and the visceral layer, closely adhering to the heart's surface, forming the epicardium. 3. The epicardium is a thin, protective layer covering the heart's outer surface. The myocardium, consisting of cardiac muscle cells, forms the bulk of the heart wall and is responsible for the vigorous contractions that propel blood throughout the circulatory system. The endocardium, lining the inner chambers and valves, ensures smooth blood flow, preventing clot formation. 4. The left and right atria, located in the upper chambers, receive blood. The left atrium collects oxygenated blood from the lungs, while the right atrium receives deoxygenated blood from the body. The left ventricle pumps oxygenated blood into the systemic circulation through the aorta, and the right ventricle sends deoxygenated blood to the lungs via the pulmonary artery. 5. Tricuspid and bicuspid (mitral) valves are AV valves separating atria from ventricles. The aortic and pulmonary semilunar valves guard the exits of the left ventricle and right ventricle, respectively. Valves prevent blood backflow, ensuring unidirectional flow during each heartbeat. 6. Blood flows from the superior and inferior vena cava into the right atrium, through the tricuspid valve to the right ventricle, then is pumped into the pulmonary circulation via the pulmonary artery. Oxygenated blood returns to the left atrium through the pulmonary veins, flows through the bicuspid valve to the left ventricle, and is ejected into the systemic circulation through the aorta. 7. The coronary arteries supply oxygenated blood to the heart muscle. The left coronary artery bifurcates into the left anterior descending artery, providing blood to the interventricular septum and anterior walls, and the circumflex artery, supplying the left atrium and lateral ventricular walls. The right coronary artery nourishes the right atrium and ventricle. 8. Cardiac muscle is characterized by striations and involuntary contractions. Intercalated discs facilitate communication between cells, ensuring coordinated contractions. Unlike skeletal muscle, cardiac muscle contracts rhythmically and continuously without fatigue. 9. Excitation-contraction coupling involves the depolarization of cardiac cells, leading to calcium release from the sarcoplasmic reticulum. Calcium binds to troponin, initiating muscle contraction. 10. Pacemaker cells in the sinoatrial (SA) node generate spontaneous action potentials, initiating the heartbeat. Contractile cells exhibit stable resting potentials and generate action potentials upon stimulation, allowing for muscle contraction. 11. The conduction system includes the SA node, initiating the electrical impulse; the AV node, delaying the signal for atrial contraction; the bundle of His, conducting the signal through the septum; and the Purkinje fibers, distributing the impulse to the ventricular myocardium. 12. An ECG tracing displays the P wave (atrial depolarization), QRS complex (ventricular depolarization), and T wave (ventricular repolarization). Abnormalities such as arrhythmias, conduction blocks, or irregularities in wave patterns can be detected. 13. The cardiac cycle consists of systole, where the heart contracts, and diastole, the relaxation phase. Atrial contraction precedes ventricular contraction, allowing for efficient blood ejection and refilling. 14. Normal heart sounds, S1 and S2, result from the closure of heart valves during the cardiac cycle. Heart murmurs, abnormal sounds, can indicate valve dysfunction, stenosis, or regurgitation. 15. Stroke volume, the amount of blood pumped per heartbeat, is influenced by preload (volume of blood in the ventricles before contraction), afterload (resistance the heart faces during ejection), and contractility (force of myocardial contraction). Heart rate is regulated by factors such as autonomic activity, hormones, and ion concentrations. 16. The autonomic nervous system modulates cardiac output. Sympathetic stimulation increases heart rate and contractility through norepinephrine release, while parasympathetic stimulation, mediated by the vagus nerve, slows heart rate by releasing acetylcholine. This dynamic balance ensures the heart responds appropriately to changing physiological demands.