Anatomy internal organs human body.

• published: 28 Feb 2015
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The human body includes the entire structure of a human being and comprises a head, neck, trunk (which includes the thorax and abdomen), arms and hands, legs and feet. Every part of the body is composed of various types of cell.[1] At maturity, the estimated average number of cells in the body is given as 37.2 trillion. This number is stated to be of partial data and to be used as a starting point for further calculations. The number given is arrived at by totalling the cell numbers of all the organs of the body and cell types.[2] The composition of the human body is made up of a number of certain elements including carbon, calcium and phosphorus. The study of the human body involves anatomy and physiology. The human body can show anatomical non-pathological anomalies known as variations which need to be able to be recognised. Physiology focuses on the systems and their organs of the human body and their functions. Many systems and mechanisms interact in order to maintain homeostasis. Skeletal structure frames the overall shape of the body and does not alter much over a lifetime. General body shape (and female body shape) is influenced by the distribution of muscle and fat tissue and is also affected by various hormones. The average height of an adult male human (in developed countries) is about 1.7–1.8 m (5'7" to 5'11") and the adult female is about 1.6–1.7 m (5'2" to 5'7") .[3] Height is largely determined by genes and diet. Body type and composition are influenced by factors such as genetics, diet, and exercise. The human body has several body cavities the largest of which is the abdominopelvic cavity. These cavities house the various body organs including the spinal cord which also accommodates the production and flow of cerebrospinal fluid in the ventricular system of the brain. Many other smaller cavities exist throughout the body called sinuses, which have varied functions. Sinuses in general usage refers to the paranasal sinuses which are involved in the condition sinusitis. The paranasal sinuses are four pairs of vital air-cavities in the cranial bones. These air-filled spaces are paired between the eyes, above the eyes, deeper behind the eyes and around the nasal cavity. Human anatomy (gr. ἀνατομία, "dissection", from ἀνά, "up", and τέμνειν, "cut") is primarily the scientific study of the morphology of the human body.[4] Anatomy is subdivided into gross anatomy and microscopic anatomy (histology)[4] Gross anatomy (also called topographical anatomy, regional anatomy, or anthropotomy) is the study of anatomical structures that can be seen by the naked eye.[4] Microscopic anatomy involves the use of microscopes to study minute anatomical structures, and is the field of histology which studies the organization of tissues at all levels, from cell biology (previously called cytology), to organs.[4] Anatomy, human physiology (the study of function), and biochemistry (the study of the chemistry of living structures) are complementary basic medical sciences,[5] that are generally taught together (or in tandem) to students studying medicine. Front view of viscera In some of its facets human anatomy is closely related to embryology, comparative anatomy and comparative embryology,[4] through common roots in evolution; for example, much of the human body maintains the ancient segmental pattern that is present in all vertebrates with basic units being repeated, which is particularly obvious in the vertebral column and in the ribcage, and which can be traced from the somitogenesis stage in very early embryos. Generally, physicians, dentists, physiotherapists, nurses, paramedics, radiographers, and students of certain biological sciences, learn gross anatomy and microscopic anatomy from anatomical models, skeletons, textbooks, diagrams, photographs, lectures, and tutorials. The study of microscopic anatomy (or histology) can be aided by practical experience in examining histological preparations (or slides) under a microscope; and in addition, medical and dental students generally also learn anatomy with practical experience of dissection and inspection of cadavers (corpses). A thorough working knowledge of anatomy is required for all medical doctors, especially surgeons, and doctors working in some diagnostic specialities, such as histopathology and radiology. Human anatomy, physiology, and biochemistry are basic medical sciences, generally taught to medical students in their first year at medical school. Human anatomy can be taught regionally or systemically;[4] that is, respectively, studying anatomy by bodily regions such as the head and chest, or studying by specific systems, such as the nervous or respiratory systems. The major anatomy textbook, Gray's Anatomy, has recently been reorganized from a systems format to a regional format, in line with modern teaching.[6][7]