* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Heart Dissection
Survey
Document related concepts
Electrocardiography wikipedia , lookup
Quantium Medical Cardiac Output wikipedia , lookup
Heart failure wikipedia , lookup
Hypertrophic cardiomyopathy wikipedia , lookup
Management of acute coronary syndrome wikipedia , lookup
Coronary artery disease wikipedia , lookup
Artificial heart valve wikipedia , lookup
Cardiac surgery wikipedia , lookup
Myocardial infarction wikipedia , lookup
Mitral insufficiency wikipedia , lookup
Lutembacher's syndrome wikipedia , lookup
Arrhythmogenic right ventricular dysplasia wikipedia , lookup
Atrial septal defect wikipedia , lookup
Dextro-Transposition of the great arteries wikipedia , lookup
Transcript
Biology 212 – Heart Dissection Heart Dissection Hold the heart in your hands. Identify anterior, posterior, superior, and lateral surfaces of the heart. This can be difficult. 1. Observe and describe the texture of the pericardium. 2. Where is pericardium attached to the heart? 3. What is the purpose of the pericardium? 4. 5. 6. 7. If the pericardial sac is still intact, slit open the pericardium and remove it from the heart. Observe the visceral pericardium (epicardium). Using a sharp probe, carefully prick a little of this serous membrane away from the myocardium. How does the visceral pericardium differ from that of the parietal pericardium? Examine the external surface of the heart. Notice the accumulation of adipose tissue, which in many cases marks the separation of the chambers and the location of the coronary arteries that nourish the myocardium. Carefully scrape away some of the fat with a probe or scalpel to expose the coronary blood vessels. Where is the greatest accumulation of fat? Identify the base and apex of the heart, and then identify the two wrinkled auricles, earlike flaps of tissue projecting from the atrial chambers. The balance of the heart muscle is ventricular tissue. To identify the left ventricle, compress the ventricular chambers on each side of the longitudinal fissures carrying the coronary blood vessels. The side that feels thicker and more solid is the left ventricle. The right ventricle feels much thinner and somewhat flabby when compressed. Why is the myocardium of the left ventricle thicker then that of the right? Identify the vessels at the base of the heart. Identify the superior vena cava, inferior vena cava, pulmonary trunk (dividing into pulmonary arteries), pulmonary veins, and the aorta. Where do the superior and inferior vena cavas take blood? What other structure delivers blood to the same area as the vena cavas? Is it oxygenated or deoxygenated blood? Biology 212 – Heart Dissection 8. How many pulmonary arteries do we have on our heart? Where do the pulmonary arteries take blood? Is it oxygenated or deoxygenated blood? 9. How many pulmonary veins do we have? Where do the pulmonary veins take blood? Is it oxygenated or deoxygenated blood? 10. Where is the aorta taking the blood? Is it oxygenated or deoxygenated blood? What are the first five branches off of the aorta? 11. Which has thicker walls, the aorta or the vena cavas? Why? 12. 13. Carefully clear away some of the fat between the pulmonary trunk and the aorta to expose the ligamentum arteriosum, a cordlike remnant of the ductus arteriosus. What is the purpose of the ductus arteriosus in the fetus? This particular ligament plays an important role in “deceleration” injuries (an injury incurred when your body slows down very quickly, like in a car accident). Many people die from these injuries. Why? What do you suppose might happen to the ligamentum arteriosum in a deceleration injury? Cut through the wall of the aorta until you see the aortic semilunar valve. Identify the two openings to the coronary arteries which supply the heart. Insert a probe into the superior vena cava and use scissors to cut through its wall so that you can view the interior of the right atrium. Do not extend your cut entirely through the right atrium or into the ventricle. Observe the right atrioventricular valve. 14. How many flaps/cusps does the right atrioventricular valve have? Pour some water into the right atrium and allow it to flow into the ventricle. Slowly and gently squeeze the right ventricle to watch the closing action of this valve. (If you squeeze too vigorously, you’ll get a face full of water!) Drain the water from the heart before continuing. Return to the pulmonary trunk and cut through its anterior wall until you can see the pulmonary semilunar valve. Pour some water into the base of the pulmonary trunk to observe the closing action of this valve. Biology 212 – Heart Dissection 15. How does the action of the atrioventricular valves differ from that of the semilunar valves (hint…What is the purpose of these valves? What direction does blood flow through these valves?) After observing the semilunar valve action, drain the heart once again. Return to the superior vena cava, and continue the cut made in its wall through the right atrium and right atrioventricular valve into the right ventricle. Parallel the anterior border of the interventricular septum until you “round the corner” to the dorsal aspect of the heart. Reflect the cut edges of the superior vena cava, right atrium, and right ventricle. Observe the comb-like ridges of muscle throughout most of the right atrium. This is called pectinate muscle (pectin means “comb”). 16. This muscle is covered in a layer of endothelium that makes it extremely smooth. Why is it important that this muscle be extremely smooth, smoother then other muscles in the body? Identify, on the ventral atrial wall, the large opening of the inferior vena cava and follow it to its external opening with a probe. Notice that the atrial walls in the vicinity of the vena cava are smooth and lack the roughened appearance (pectinate musculature) of the other regions of the atrial walls. Just below the inferior vena caval opening, identify the opening of the coronary sinus, which returns venous blood of the coronary circulation to the right atrium. Nearby, locate the oval depression, the fossa ovalis, in the interatrial septum. This depression marks the site of an opening in the fetal heart, the foramen ovale, which allows blood to pass from the right to the left atrium, thus bypassing the fetal lungs. 17. What would be the consequence to a child if the foramen ovale failed to close? Identify the papillary muscle in the right ventricle, and follow their attached chordae tendineae to the flaps of the tricuspid valve. Notice the pitted and ridged appearance (trabeculae carneae) of the inner ventricular muscle. Make a longitudinal incision through the aorta and continue it into the left ventricle. Notice how much thicker the myocardium of the left ventricle is than that of the right ventricle. Compare the shape of the left ventricular cavity to the shape of the right ventricular cavity. 18. Are the papillary muscle and chordae tendineae observed in the right ventricle also present in the left ventricle? Biology 212 – Heart Dissection 19. How many flaps/cusps are found on the left atrioventricular valve? Continue your incision from the left ventricle superiorly into the left atrium. Reflect the cut edges of the atrial wall, and attempt to locate the entry points of the pulmonary veins into the left atrium. Follow the pulmonary veins to the heart exterior with a probe. Notice how thin-walled these vessels are. Properly dispose of the organic debris, and clean the dissecting tray and instruments with warm, soapy water before leaving the laboratory.