the Body
Think of the body as divided into seven systems:
(click on the underlined links to learn more)
- [ bones ]
- [ brain and nerves ]
- [ muscles ]
- [ respiration ]
- [ circulation ]
- [ digestion ]
- [ glands ]
All are connected and interdependent, though each has a special network of its own.
Food provides energy and building matter for the body; digestion is the automatic process that converts it into usable units, and storage ones if necessary. The digestive system consists of the alimentary canal through which food passes; it begins at the mouth and ends at the rectum and can be anywhere from 6 to 9 meter's long, twisting and winding to fit in the space provided. Accessory organs are the liver, kidneys, pancreas and spleen.
From the moment food is eaten, it can take from fifteen to twenty-five hours to pass through the body. It is swallowed by automatic contractions in the oesophagus (the foodpipe from mouth to stomach) that propel it onward. The wave of contraction is at the rate of 2 cm or so per second and is so effective that fluids will get to the stomach even if one is upside down.
On entering the stomach, the proteins, carbohydrates and fats are broken down and changed into smaller particles of protein, glucose, amino acids, fatty acids and glycerine. This is both a chemical and mechanical process; the walls secrete digestive juices and rhythmically contract, causing food units to move into the duodenum, the first part of the small intestine. The stomach's acidity is often a problem, caused by living tissue producing fairly strong hydrochloric acid; this is sometimes diluted and neutralised by food components, but the stomach walls are always protected by alkaline juices.
Practically all digestion is carried out in the small and large intestines and a great proportion of actual absorption of food takes place through the walls. The extraction of valuable food elements is done by enzymes.
LIVER: The largest single organ in the body, it weighs about 2 kg's. One cannot live without the liver. It is made of soft, red-brown tissue divided into lobes and covered with a tough fibrous coat. A remarkable feature is that it has a double blood supply: it receives fresh arterial blood and also blood-carrying products of digestion from the intestines. At rest a quarter of the body's blood is in the liver, though a 600 - 1200 ml. can leave when exercising. The liver is the central organ of metabolism; its functions are formidable and listed as five hundred. It is capable of replacing its own tissue and its powers of self regeneration are very high.
KIDNEYS: Each kidney is a collection of filter units that absorb virtually everything small from the blood, returning to it what is required. The kidneys eliminate waste products with the formation of urine, regulate salt and liquid intake of the body and maintain the slight alkalinity of body fluids.
PANCREAS AND SPLEEN: Pour crucial digestive juices - 600 - 900 ml. daily - into the duodenum. One part of the pancreas is pure gland, secreting insulin.
[ the Body ]
Think of the body as divided into seven systems:
(click on the underlined links to learn more)
- [ bones ]
- [ brain and nerves ]
- [ muscles ]
- [ respiration ]
- [ circulation ]
- [ digestion ]
- [ glands ]
All are connected and interdependent, though each has a special network of its own.
Return to [ the Body ] Index page!