![]() ![]() This is because the heart cells quickly stop dividing and all growth occurs through size increase rather than cell division. Cancer can affect the heart, though it is exceedingly rare and has usually metastasized from another part of the body such as the lungs or breasts. Risk factors for coronary artery disease include obesity, smoking, high cholesterol, high blood pressure, lack of exercise and diabetes. It is caused by the buildup of plaque in the coronary arteries supplying the heart, eventually the arteries may become so narrow that not enough blood is able to reach the myocardium, a condition known as myocardial infarction or heart attack, this can cause heart failure or cardiac arrest and eventually death. Ĭoronary artery disease is the leading cause of death worldwide, making up 16% of all deaths. It then travels to the atrioventricular node which makes the signal slow down slightly allowing the ventricles to fill with blood before pumping it out and starting the cycle over again. It starts in the sinoatrial node traveling through the atria causing them to pump blood into the ventricles. The heart has an electrical conduction system to control the contractions and relaxation of the muscle. The purpose of the ventricles is to pump blood to the lungs through the right ventricle and to the rest of the body through the left ventricle. A lack of the atrium would cause a decrease in cardiac output of 75%. This allows enough blood to get into the ventricles during atrial systole. The primary purpose of the atrium is to allow uninterrupted venous blood flow to the heart during ventricular systole. The heart is composed of two atrium and two ventricles. ![]() Lining cells regulate what can and can't pass through them, protect internal structures, and function as sensory surfaces. Endothelial cells are cells that line internal cavities including blood vessels and glands. Ĭells that lie on surfaces exposed to the outside world or gastrointestinal tract ( epithelia) or internal cavities ( endothelium) come in numerous shapes and forms – from single layers of flat cells, to cells with small beating hair-like cilia in the lungs, to column-like cells that line the stomach. These are lining cells ( epithelia), connective tissue, nerve tissue and muscle tissue. The body consists of four main types of tissues. The study of tissues is called histology and often occurs with a microscope. The body consists of many different types of tissue, defined as cells that act with a specialised function. Human Body 101, National Geographic, 5:10 However, not all cells have DNA some cells such as mature red blood cells lose their nucleus as they mature. Proteins dictate cell function and gene expression, a cell is able to self-regulate by the amount of proteins produced. The RNA is then used to create proteins which form the basis for cells, their activity, and their products. Here, parts of DNA are copied and sent to the body of the cell via RNA. Cells Ĭells in the body function because of DNA. The main electrolytes in body water outside cells are sodium and chloride, whereas within cells it is potassium and other phosphates. The content, acidity and composition of the water inside and outside cells is carefully maintained. This is made up of about 19 litres (4.2 imp gal 5.0 US gal) of extracellular fluid including about 3.2 litres (0.70 imp gal 0.85 US gal) of blood plasma and about 8.4 litres (1.8 imp gal 2.2 US gal) of interstitial fluid, and about 23 litres (5.1 imp gal 6.1 US gal) of fluid inside cells. The adult male body is about 60% water for a total water content of some 42 litres (9.2 imp gal 11 US gal). These elements reside in trillions of cells and non-cellular components of the body. The human body is composed of elements including hydrogen, oxygen, carbon, calcium and phosphorus. Trace elements are less than 1% combined (and each less than 0.1%). The body is studied by health professionals, physiologists, anatomists, and by artists to assist them in their work.Ĭomposition Elements of the human body by mass. Many systems and mechanisms interact in order to maintain homeostasis, with safe levels of substances such as sugar and oxygen in the blood. Physiology focuses on the systems and organs of the human body and their functions. The body varies anatomically in known ways. The study of the human body involves anatomy, physiology, histology and embryology. It comprises a head, neck, trunk (which includes the thorax and abdomen), arms and hands, legs and feet. They ensure homeostasis and the viability of the human body. It is composed of many different types of cells that together create tissues and subsequently organ systems. The human body is the structure of a human being. Naturally-occurring pubic, body, and facial hair has been deliberately removed to show anatomy Female (left) and male (right) adult human bodies photographed in ventral (above) and dorsal (below) perspectives. ![]()
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