explain our body in two pages
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Answer:
The human body is the structure of a human being. It is composed of many different types of cells that together create tissues and subsequently organ systems. They ensure homeostasis and the viability of the human body.
Female (left) and male (right) adult human bodies photographed in ventral (above) and dorsal (below) perspectives. Naturally-occurring pubic, body, and facial hair has been deliberately removed to show anatomy
It comprises a head, neck, trunk (which includes the thorax and abdomen), arms and hands, legs and feet.
The study of the human body involves anatomy, physiology, histology and embryology. The body varies anatomically in known ways. Physiology focuses on the systems and organs of the human body and their functions. Many systems and mechanisms interact in order to maintain homeostasis, with safe levels of substances such as sugar and oxygen in the blood.
The body is studied by health professionals, physiologists, anatomists, and by artists to assist them in their work.
Explanation:
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The human body is composed of elements including hydrogen, oxygen, carbon, calcium and phosphorus.[1] These elements reside in trillions of cells and non-cellular components of the body.
The adult male body is about 60% water for a total water content of some 42 litres (9.2 imp gal; 11 US gal). 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.[2] The content, acidity and composition of the water inside and outside cells is carefully maintained. The main electrolytes in body water outside cells are sodium and chloride, whereas within cells it is potassium and other phosphates.[3]
Genome Edit
Main article: Genome
See also: Genetics
Cells in the body function because of DNA. DNA sits within the nucleus of a cell. Here, parts of DNA are copied and sent to the body of the cell via RNA.[8] The RNA is then used to create proteins which form the basis for cells, their activity, and their products. Proteins dictate cell function and gene expression, a cell is able to self-regulate by the amount of proteins produced.[9] However, not all cells have DNA; some cells such as mature red blood cells lose their nucleus as they mature.
Tissues Edit
External video
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video icon Human Body 101, National Geographic, 5:10
The body consists of many different types of tissue, defined as cells that act with a specialised function.[10] The study of tissues is called histology and often occurs with a microscope. The body consists of four main types of tissues – lining cells (epithelia), connective tissue, nerve tissue and muscle tissue.[11]
Cells 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. Endothelial cells are cells that line internal cavities including blood vessels and glands. Lining cells regulate what can and can't pass through them, protect internal structures, and function as sensory surfaces.[11]
Organs Edit
See also: List of organs of the human body
Organs, structured collections of cells with a specific function,[12] mostly sit within the body, with the exception of skin. Examples include the heart, lungs and liver. Many organs reside within cavities within the body. These cavities include the abdomen (which contains the stomach, for example) and pleura, which contains the lungs.
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Immune system Edit
Main article: Immune system
The immune system consists of the white blood cells, the thymus, lymph nodes and lymph channels, which are also part of the lymphatic system. The immune system provides a mechanism for the body to distinguish its own cells and tissues from outside cells and substances and to neutralize or destroy the latter by using specialized proteins such as antibodies, cytokines, and toll-like receptors, among many others.[20]
Answer
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Digestive system Edit
Main article: Digestive system
The digestive system consists of the mouth including the tongue and teeth, esophagus, stomach, (gastrointestinal tract, small and large intestines, and rectum), as well as the liver, pancreas, gallbladder, and salivary glands. It converts food into small, nutritional, non-toxic molecules for distribution and absorption into the body. These molecules take the form of proteins (which are broken down into amino acids), fats, vitamins and minerals (the last of which are mainly ionic rather than molecular). After being swallowed, food moves through the gastrointestinal tract by means of peristalsis: the systematic expansion and contraction of muscles to push food from one area to the next.[17][18]
Digestion begins in the mouth, which chews food into smaller pieces for easier digestion. Then it is swallowed, and moves through the esophagus to the stomach. In the stomach, food is mixed with gastric acids to allow the extraction of nutrients. What is left is called chyme; this then moves into the small intestine, which absorbs the nutrients and water from the chyme. What remains passes on to the large intestine, where it is dried to form feces; these are then stored in the rectum until they are expelled through the anus.[18]
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Endocrine system Edit
Main article: Endocrine system
The endocrine system consists of the principal endocrine glands: the pituitary, thyroid, adrenals, pancreas, parathyroids, and gonads, but nearly all organs and tissues produce specific endocrine hormones as well. The endocrine hormones serve as signals from one body system to another regarding an enormous array of conditions, and resulting in variety of changes of function.[19]