Coronary heart disease
Introduction to the heart
The structure and function of the heart
- Pulmonary valve → this valve restricts blood flow between the right ventricle and the pulmonary artery
- Pulmonary arteries → this arteries carries deoxygenated blood from heart to the lungs
- Right atrium - it is one of the four chambers in the heart, which receives deoxygenated blood from the inferior vena cava and the superior vena cava, and pups the blood into the right ventricle through the tricuspid valve
- Right ventricle → it is one of the four chambers in the heart. It is situated below the right atrium, and it receives deoxygenated blood from the right ventricle through the tricuspid valve (as seen before) and pumps the deoxygenated blood pulmonary artery through the pulmonary trunk (not labelled).
- Aorta → this is the largest (i.e. it is the artery with the biggest diameter) in human body. The aorta stretches from the left ventricle to the abdomen
- Pulmonary veins → these veins carries oxygenated blood from lungs to the hearts
Inside the heart, there are four chambers/cavities fill with blood. Two of these cavities are called atria. The other two are called ventricles. The two atria are situated at the top of the heart (as seen in the diagram). The ventricles are situated at the bottom of the heart. The left ventricle contracts most forcefully because it needs to pump blood around the body, whereas the right ventricle only needs to pump blood to the lungs. so you can best feel your heart pumping on the left side of your chest. That is why the wall of the left ventricle is thicker than of the right ventricle. Each side of the heart houses one ventricle and one atrium. A wall, called the septum, separates the right and left sides of the heart. A valve connects each atrium to the ventricle below it. The mitral valve connects the left atrium with the left ventricle. The tricuspid valve connects the right atrium with the right ventricle.Now, lets look at the heart as a whole. Many large vessels are connected to the top of the heart. One of the vessels is the largest artery (in the body), called the aorta, which carries nutrient-rich blood away from the heart. Another important vessel is the pulmonary artery which connects the heart with the lungs as part of the pulmonary circulation system. The two largest veins that carry blood into the heart are the superior vena cava and the inferior vena cava. They are called "vena cava" because they are the "heart's veins." The superior is located near the top of the heart. The inferior is located beneath the superior. The heart's structure makes it an efficient, never-ceasing pump. From the moment of the heart appears in our body (when we are a fetus) till the moment we die, the heart pumps constantly. The heart, therefore, has to be strong. The average heart's muscle, called cardiac muscle, contracts and relaxes about 70 to 80 times per minute involuntarily (you don’t need initiate the action). As the cardiac muscle contracts it pushes blood through the chambers and into the vessels. Nerves connected to the heart regulate the speed with which the muscle contracts (these nerves regulate the pacemaker cells). The heart is split into two different parts, the right side and the left side. The right side of the heart receives deoxygenated (blood with low levels of oxygen) blood from the body tissues (the blood from the upper part of the body is received by Superior Vena Cava whereas the blood from the lower part of the body is received from the Inferior Vena Cava) into the right atrium. This deoxygenated blood passes through the tricuspid valve into the right ventricle. This blood is then pumped under higher pressure from the right ventricle to the lungs via the pulmonary artery The left-hand side of the heart receives oxygenated blood from the lungs (via the pulmonary veins) into the left atrium. This oxygenated blood then passes through the bicuspid valve into the left ventricle. It is then pumped to the aorta under greater pressure.This higher pressure ensures that the oxygenated blood leaving the heart via the aorta is effectively delivered to other parts of the body via the vascular system of blood vessels.
Coronary heart disease So what is Coronary Heart Disease, why does it happen and what are the risk factors?Coronary heart disease(sometimes abbreviated as CHD)is also known as atherosclerotic heart disease or ischemic heart disease. CHD is the most common type of heart disease and cause of heart attack. This disease is caused by the build-up of fatty material, which obstructs the flow of blood to the heart, building up in the wall of the coronary arteries. This is detrimental to the health of the heart because heart needs a constant supply of blood for muscle contraction to happen, which requires cells to respire, and without enough supply of blood, the cell that make up the heart will not be able to respire as fast as they should. As the fatty deposits builds up, the inner lining of the coronary arteries slowly become filled with substance called plaque, which is formed from cholesterol. This process of fat clogging up in coronary arteries is called atherosclerosis. Not only does the plaque narrow the coronary arteries, but also it block nutrients being delivered to the artery walls, which means the arteries lose their elasticity. In turn, this can lead to high blood pressure, which also increases the risk of heart disease. This same process goes on in the arteries throughout the body, and can lead to high blood pressure which puts further strain on the heart. Some people who have CHD have it because of genetic factors - which made them more vulnerable to atherosclerosis. A clue to know if one has a higher risk of getting CHD is by checking family history of heart disease in middle-age. Genetic factors are not the only reason one might develop, lifestyle factors (environmental factors) also increase the risk include an unhealthy diet, lack of exercise, diabetes, stress, obesity/overweight, high blood pressure and, most importantly, smoking. Also, some research suggest that gender and age may affect the probability of one getting CHD. Historically, men were thought to have more chance getting CHD than women, but in recent years, CHD has claimed women and men in nearly equal numbers.
The symptoms of CHDAs discussed earlier, coronary heart disease happens when a plaque forms in the arteries (called coronaries) that deliver blood to the heart. If the arteries are partially blocked (meaning that the plaque does not completely clog-up the artery’s cavity), the person with CHD could experience angina. Angina is severe chest pain that can spread across the upper part of the body because the heart experiences difficulties while trying to pump blood around the body without adequate supply of oxygen. Angina is the most common symptom of CHD. When one’s artery becomes completely blocked with plaque, he/she gets a heart attack. During a heart attack, one can experiences these symptoms:
- sweating
- light headedness
- nausea
- breathlessness
How can CHD be preventedAs discussed before, some risk factors of CHD can be controlled. The first step one can take to prevent CHD is to exercise and follow a healthy diet/balanced diet. Specifically, one needs to eat:
- vegetables
- fruits
- whole grains
- fat-free (or low fat) dairy products
- food high in unsaturated fat which help us to reduce our cholesterol - e.g. oily fish (cod), avocados, sunflower, rapeseed, olive and vegetable oils.
- protein food
- seafood
- processed soy products
- nuts
- seeds
- beans
- peas
- less sugary foods
A good diet is important because it keeps our blood pressure under control. Furthermore, obesity affects the risks of CHD, so if a person is obese, he or she needs to go to the doctor to create a reasonable weight-loss plan. Quitting smoking also helps. Smoking can damage and tighten the blood vessels in our body. If there is a family-history of problems with CHD, one may need to go to the doctor. Sometimes, controlling lifestyle choices may not be enough, one may need to take medicine that have been prescribed to them by doctor to mitigate the risk of having CHD.
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