Disorders of the heart
The cardiovascular system is an elaborate network that performs 2 major tasks. Firstly it delivers oxygen and nutrients to body organs and secondly it removes waste products of metabolism from tissue cells.The major components of the heart are a hollow muscular pump and a circulatory system of large and small elastic vessels that transport blood throughout the body.The heart is the central organ of the cardiovascular system and it is located between the two lungs in the middle of the chest, although two-thirds of the heart lies to the left of the breastbone and one-third to the right. The adult heart is approximately the size of two clenched fists and it is shaped like a cone, weighing between 7 to 15 ounces depending on the size of the individual.The human heart is divided into four chambers - the right atrium and the right ventricle and the left atrium and the left ventricle. The walls of the chambers are made up of myocardium muscle that contracts rhythmically under the stimulation of electric currents. A wall of muscle called the septum separates the left and right atria and the left and right ventricles from each other. (See Appendix 1a)
During diastole, the sinus node generates an impulse that forces the two atria to contract. Congenital defects and rheumatic valvular disease are major predisposing factors along with bicuspid or calcific aortic valves, mitral valve prolapse, hypertrophic sub aortic stenosis, and prosthetic valves. From the rioventricular node, they travel along the bundle of His and along the purkinje fibres pathways (named after the scientists who first discovered them). The Circulation SystemBlood returning from the body through the venous system enters the heart through the right atrium, where it collects and is then pumped to the right ventricle. PericarditisInfections resulting in acute percarditis may be caused by bacteria, parasites, protozoa, viruses or fungi. The Cardiac CycleElectrical activity coordinates the rhythmic contraction and relaxation of the hearts chambers known as the cardiac cycle. The cardiac cycle consists of two phases, which are called Diastole and Systole. Another sensation may be that patients sometimes mention a fluttering feeling in the chest or neck. Abnormal heart rhythms fall into two general classes:Excessively slow heart rates known as Bradycardias Over rapid heart rates known as TachycardiasThe classic symptoms of arrhythmias include palpitations, dizziness, fainting, chest pain and shortness of breath. On the outside the heart is encased in a fibrous double layered sac called the pericardium. By recognising the fundamental defects in channelopathies may provide the basis for new strategies of treatment including tailor made pharmacotherapy and gene therapy. The Conduction SystemElectrical currents that regulate the heart rhythm originate in cells of the heart muscle and travel through a network of specialised fibres referred to as the hearts conduction system. This coronary shows only mild atherosclerosis, with only an occasional yellow-tan lipid plaque and no narrowing Appendix 2a) This is the left coronary artery from the aortic root on the left. In advanced cases abnormalities include; breathlessness, palpitations, heart arrhythmias, swollen feet, dizziness and chest pain. High blood pressure results when the hearts efforts to pump blood meet with higher than normal resistance in the blood vessels outside the heart.
Common topics in this essay:
Arrhythmias Abnormalities,
Endocarditus ABE,
Pericarditis Infections,
Rheumatic Fever,
Systole Diastole,
Normal Heart,
Heart Circulation,
Valves Blood,
Physiology Seeley,
Wrong Heart,
heart disease,
heart muscle,
cardiac cycle,
rheumatic fever,
congenital heart,
coronary artery,
left ventricle,
heart valves,
infective endocarditis,
left atrium,
tricuspid mitral valves,
congenital heart disease,
low density lipoproteins,
pulmonary artery aorta,
bundle purkinje fibres,
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