Heart Dissection Process - Assignment Example

Written practical report on heart dissection HEART DISSECTION The first and the foremost step in heart dissection is the removal of the heart from the pericardial cavity and studying its features. Secondly, the epicardium which is also called the visceral pericardium and epicardial fat is removed. While doing this procedure, it is important to take care and avoid any kind of injury to the minute cardiac veins that cross the artery on the surface. Each and every incision needs to be done with utmost care. During this process it is important to identify all the branches of coronary arteries and veins. Once all these are studied carefully it is essential to cut open the heart chambers and study the chambers of the heart by opening them in the sequence of the blood flow. Now it is time to clean the heart chambers from the clogged blood that remains in the heart. Clean out the chambers and recognize their anatomical features such as the endocardium, right atrium, superior and inferior venae cavae, and coronary sinus (valve), pectinate muscle, Left atrium, pulmonary veins, Left ventricle, and all other features. It is also vital to study the specific functions as well as the exact name of each part of the heart (The University of Michigan, 2000). While each and every part of heart has its distinctive functions, it is very essential to understand the problems linked to each part. Heart is often compared to a machine that pumps blood to each and every part of out body. (i) Specify the general functions of blood and describe the structure and function of all blood components including plasma. Blood is the life-supporting fluid that circulates the oxygen and nutrients to each and every cell in our body. Blood cells are made in the bone marrow which is a spongy material in the center of the bones. It is estimated that human blood is made up of about 22 percent solids and 78 percent water. The components of human blood are: Plasma is the fluid part of the blood, in which the blood cells are suspended. Red blood cells or the erythrocytes have a 120 days lifespan and carry oxygen from the lungs to the rest of the body. White blood cells or the leukocytes are our major help to fight infections and aid in the immune process. There are different types of WBCs and they are lymphocytes, monocytes, eosinophils, basophils, neutrophils and platelets or the thrombocytes which help in clotting process. Hemoglobin is a key protein in the red blood cells that carries oxygen from the lungs to all parts of our body. Platelets are much smaller in size than the other blood cells. During a clotting process platelets group together to form clumps to stop bleeding (The University of Michigan, 2000). (ii) Humans have a double circulation, blood enters the heart and it is pumped to the lungs and returns to the heart where further pumping propels it through the rest of the body. a) draw a flow diagram to show the movement of blood around the body and indicate whether the blood is oxygenated or deoxygenated. Name the major vessels in circulation. Double Circulation (Source: Polar Electro, 2005) b) Evaluate the differences between arteries, veins and capillaries. Arteries are muscular blood vessels that originate from the heart and carry oxygenated blood to all parts of the body including each and every cell in the body. However, the exception is with the pulmonary and umbilical arteries that carry deoxygenated blood. Veins are blood vessels that carry deoxygenated blood from each and every part of the body and bring it back to the heart for further oxygenation. The deoxygenated blood is then sent for purification into the lungs. The exceptions with the veins are with the pulmonary and umbilical veins that are known to carry oxygenated blood. Capillaries are the smallest vessels in the human body that actually enable the interchange of water, oxygen, carbon dioxide, and many other nutrient and waste chemical substances between blood and surrounding tissues. These vessels are of the size of 5-10 μm in diameter and connect arterioles and venules (Wikipedia, 2008a). (iii) The cardiac cycle refers to the sequence of events of a heartbeat. Use diagram to illustrate the cardiac cycle and describe each stage. Explain how it's coordinated referring to the SA node, AV node, Bundle of His and the Purkinje fibres. A single cycle of cardiac activity can be mainly being divided into two basic stages i.e. the diastole and the systole. When the blood pressure is checked it is basically the measure of the diastolic and the systolic pressure that is measured. During the diastole, ventricular filling takes place and begins from a short period just former to filling during which the ventricles are relaxing.  The second stage is systole and is defined by the contraction and ejection of blood from the ventricles (Klabunde, 1999). Scientist have further divided these two stages into seven stages (See Figure) that include the Stage I- Atrial Contraction; Stage II-Isovolumetric Contraction, Stage III- Rapid Ejection, Stage IV- Reduced Ejection, Stage V- Isovolumetric Relaxation, Stage VI- Rapid Filling and the final Stage VII- Reduced Filling. In fact the rhythmic sequence of contractions and relaxation of the heart is controlled and coordinated by the sinoatrial (SA), atrioventricular (AV) nodes, bundles of His and the Purkinje fibers. The sinoatrial node is also known as the cardiac pacemaker. It is located in the upper wall of the right atrium and initiates the wave of electrical stimulation that starts the atrial contraction by creating an action potential. Soon this wave reaches the atrioventricular nodes which that are located in the lower right atrium. The wave is delayed there prior to being conducted through the bundles of His and back up the Purkinje fibers, resulting in the contraction of the ventricles (Wikipedia, 2008b). (iv) The heart rate or pulse always goes up after exercise. Deduce the reason for the increase in heart rate during exercise. What is blood pressure? Outline the causes of high blood pressure and explain how blood pressure is normally maintained. The reason for the increase in the heart rate during exercise is just as all other muscles in the body, the heart also becomes stronger and larger, so that during exercise it can pump more blood through the body. Regular exercise is essential to maintain a good health and efficient heart. In fact studies have proven that the resting heart rate of the people who do regular exercise is also slower for the reason that less effort is required to pump blood (The HealthCentral Network, 2005). Blood pressure is defined as the force by which the blood pushes against the walls of the arteries. The heart beats on an average 70 times a minute and every time the heart beats it pumps out blood into the arteries. When we measure the blood pressure of a person it is always represented by the two numbers, the systolic and diastolic pressures. In general, a normal blood pressure is below 120/80 mmHg. A person who has a blood pressure of 140/90 mmHg or higher is suffering from hypertension. In this case the heart will have to works harder, and the chances of a stroke, heart attack, and kidney problems are higher (National heart lung and blood institute, 2006). While there are several studies that have found the causes of hypertension there is a small number of people who have secondary hypertension. In other words in such cases the there is an underlying cause of their high blood pressure. Some develop high blood pressure if they have problems with their kidneys or adrenal glands that are known to produce hormones that are important in controlling blood pressure (Blood pressure association, 2005). Some of the common reasons for high blood pressure are as follows: hereditary, mental tension and stress, excess intake of common salt, over-weight and obesity, sedentary life- style, smoking and excess intake of alcohol (Blood pressure association, 2005). Today with the advancement of medical sciences, there are several treatments using drugs to control hypertension. Other than drugs, regular exercise, calcium supplements, reducing the intake of salt, using monounsaturated fats instead of polyunsaturated fats are known for their roles in reducing high blood pressure. Additionally a combination diet that emphasizes on fruits, vegetables, and low-fat dairy products and also includes whole grains, poultry, fish, and nuts is considered as very good for people with hypertension. A diet reduced in fats, red meat, sweets, and sugar-containing beverages has also shown to decrease blood pressure (Plaisted, et al. 1999). (v) Heart disease is a major killer in the UK. Explain in detail how atherosclerosis leads to coronary heart disease. Outline some of the treatments available to reduce mortality. Atherosclerosis is a gradual, complex disease that probably begins at a very young age and progresses at older age. There are several causes of damage to the arterial wall. Some of the most common causes include: an elevated levels of cholesterol and triglyceride in the blood; hypertension; active or passive tobacco smoking; and diabetes.  Arthrosclerosis occurs in the walls of arteries mainly due to the damage to the endothelium. At this site fats, cholesterol, platelets, cellular debris, calcium and other substances are deposited causing in the build up of plaque. As a result of these cells and surrounding material, the endothelium thickens and the artery's diameter reduces and blood flow decreases, reducing the oxygen supply especially to the cardiac muscles. “Often a blood clot forms next to this plaque and blocks the artery completely, stopping the blood flow” (American Heart Association, 2008). Treatments for atherosclerosis may include lifestyle changes, medicines, and medical procedures or surgery. Angioplasty is a procedure to open blocked or narrowed coronary arteries with the help of stent. Angioplasty is a simple and very common procedure carried out in many cardiac care hospitals. This process can improve the blood supply to the heart, relieve chest pain, and possibly prevent a heart attack. Coronary artery bypass grafting (CABG) is another type of procedure that is done in patients suffering from atherosclerosis. It is a surgical procedure and involves complicated processes when compared to angioplasty. In this process arteries or veins from other parts of the body particularly from the hand or the legs are used to bypass the narrowed coronary arteries. CABG can improve blood flow to the heart, relieve chest pain, and possibly prevent a heart attack (National heart lung and blood institute, n. d). vi) Blood transfusions might sometimes be necessary to save lives. Blood will need to be matched for compatibility by testing the blood groups. Explain how blood groups are determined explaining the significance of blood groups referring to the ABO blood groups and Rhesus factor in your answer. Blood can be considered as the most important element in the body. It is the carrier of oxygen, nutrients and also helps in the immune process. Additionally it also allows removing the harmful wastes from the body. Each individual has a particular blood group which is classified based the presence or absence of inherited antigenic substances on the surface of the RBCs. Blood types are inherited and correspond to contributions from both parents. There are four different blood types and has Rh factors that make it even more unique. Blood groups can easily be determined in a laboratory. If a person has blood group A then he/she has the A antigens covering the RBCs and if the person has blood group B, it is the B antigens that cover the RBCs. People with group O have neither of the antigens, and group AB has some of both. “The ABO system is the most significant blood group system in human blood transfusion. The related anti-A antibodies and anti-B antibodies are generally "Immunoglobulin M", abbreviated IgM, antibodies. ABO IgM antibodies are formed in the initial years of life by sensitization to environmental substances like food, bacteria and viruses. The "O" in ABO is often called "0" (zero/null) in other languages”. Secondly, “the Rhesus system (Rh system) is the most significant blood group system in human blood transfusion. Among the rhesus antigen the most significant Rhesus antigen is the RhD antigen. This is because RhD antigen is the most immunogenic among the five main rhesus antigens. RhD negative individuals can produce IgG anti-RhD antibodies soon after a sensitizing event such as a delivery” (Wikipedia, 2008c). References American Heart Association, (2008) Atherosclerosis Retrieved on 23 February 2008 from http://www.americanheart.org/presenter.jhtml?identifier=4440 Blood pressure association, (2005) What is High Blood Pressure? Retrieved on 23 February 2008 from http://www.bpassoc.org.uk/information/what_is/what_is.htm Klabunde, R.E. (1999) Cardiovascular Physiology Concepts, Retrieved on 23 February 2008 from http://www.cvphysiology.com/ National heart lung and blood institute, (2006) What Is High Blood Pressure? Retrieved on 23 February 2008 from http://www.nhlbi.nih.gov/health/dci/Diseases/Hbp/HBP_WhatIs.html National heart lung and blood institute, (N.D) How Is Atherosclerosis Treated?, Retrieved on 23 February 2008 from http://www.nhlbi.nih.gov/health/ Plaisted, C.S. et al. (1999) The effects of dietary patterns on quality of life: a substudy of the Dietary Approaches to Stop Hypertension trial, J Am Diet Assoc. Aug;99 (8 Suppl) : S84-89. Polar Electro, (2005) Why Heart Rate Monitoring, Retrieved on 23 February 2008 from http://www.pursuit-performance.com.au/polar/html/polar/about_hrm.html The HealthCentral Network, (2005) impact of exercise on heart beat, Retrieved on 23 February 2008 from http://www.healthcentral.com/diet-exercise/exercise-000029_3-145.html The University of Michigan, (2000) Lab Manual – Heart, Retrieved on 23 February 2008 from http://anatomy.med.umich.edu/cardiovascular_system/heart.html Wikipedia, (2008a) Arteries, Veins and Capillaries, Retrieved on 23 February 2008 from http://en.wikipedia.org/wiki/ Wikipedia, (2008b) Cardiac cycle, Retrieved on 23 February 2008 from http://en.wikipedia.org/wiki/Cardiac_cycle Wikipedia, (2008c) Blood type, Retrieved on 23 February 2008 from http://en.wikipedia.org/wiki/Blood_type Read More