1. THE MECHANISMS OF THE BODY SYSTEM
The Mechanisms of the systems in our body are working automatically and consistent with one another. We have to learn and understand how to manage and maintain the efficiency of the mechanisms of the body to last as long as possible.
Each body systems have a different function but work systematically together. The 5 significant systems in our body have the following functions and associated organs:
1. THE DIGESTIVE SYSTEM
Human beings consume food so that the body can grow, maintain and reconstruct damaged organs. Humans thus have a digestive system to transport nutrient and water and convert it into energy for the body to use.
Digestion is the process of changing larger food particles into smaller ones which the body can absorb and use. The digestive system can be divided into 3 sections.
1. Digestion within the mouth. This is the first step in the process of digestion. The body organs related to this step are the teeth and salivary glands. The gastrointestinal (GI) tract of the body begins with the mouth and the teeth for chewing food and the salivary glands to digest starch. The saliva has a slimy consistency to help swallowing any food substances easier. The amount of saliva produced depends on the taste and smell of the food. After the food has been ground in the mouth, it can be swallowed through the GI tract.
2. Digestion within a stomach. The next organ in the GI tract is the stomach. It is under the left diaphragm and above the small intestine It is a bag in the shape of the letter J. Its wall is a smooth and flexible muscle. The strong stomach muscle is very flexible and can be expanded to hold 1,000 – 1,200 c.c. There are 2 sphincter muscles, one is connected to the upper GI tract; the other is connected to the small intestine. Glands within the stomach wall secret enzymes and acids to aid in the digestion of food. Whenever food passes into the stomach, the glands will be given an impulse to produce the enzymes and acids. The hydrochloric acid can change pepsinogen and trirennin secreted from the stomach wall into pepsin and rennin which digest protein. The acid in the stomach also destroys bacteria in the food. Depending on the kind of food digestion will last from about 30 minutes to 3 hours. Proteins will be digested within the stomach by the pepsin enzyme. The stomach absorbs some nutrients; for example, it can absorb 30 – 40 percent of alcohol present in the food.
3. Digestion within the small intestine. The small intestine is connected to the stomach via the pyloric sphincter. The small intestine looks like a curling tube in the abdominal cavity. It is 5-7 meters long. The small intestine produces enzymes to digest proteins, carbohydrates, and fats.
For further digestion in the small intestine, the food moves from the stomach through the pyloric sphincter into the small intestine. Digestion in the small intestine is aided by three organs; the pancreas, the small intestine wall and the liver.
The pancreas builds hormones to control the blood sugar and enzymes to digest food. The enzymes produced by the pancreas cannot be used without the enzymes from the small intestine. This mixture of enzymes is able to digest protein. The panaceas also produce enzymes to digest carbohydrates and fats. It also produces sodium hydrogen carbonate which is a base and reduces stomach acidity.
The small intestine wall produces enzymes to digest proteins, carbohydrates, and fats. The small intestine can be divided into 3 structural parts:
• Duodenum
• Jejunum
• Ileum
The liver produces bile which is stored in the gall bladder. Bile helps to disperse and dissolve fat in water. Lipase enzymes from the pancreas and the small intestine help to digest fats into fatty acid and glycerides (acylglycerols).
ABSORPTION
Most absorption of nutrients happens in the small intestine. The inner wall of the small intestine is covered with wrinkles called plicae circulares. Microscopic finger-like pieces of tissue project from the inner wall, they are called villi. At the outer area of a villus cell are some projections of tissue which we call microvilli. The function of the plicae circulares, the villi and the microvilli are to extend the total area available for the absorption of nutrients. Blood and lymph vessels in each villus take the nutrients by permeation from the small intestine wall.
Almost all of the nutrient including a variety of vitamins will be absorbed at the duodenum. The jejunum will absorb the fatty acids while the ileum will absorb vitamin B12 and bile salt. Most of the nutrients and water will be transported into capillaries of the villi. Monosaccharides, amino acids and fatty acids will pass into the capillaries and the veins and will be transported into the liver and finally into the heart. Monosaccharide, of which more is absorbed than we need, will be synthesized into glycogen and is stored in the liver and muscles. Glycogen stored in the liver will be changed into glucose and is brought to cells as energy source.
FATTY ACIDS will get into the blood. It is used as energy source and to build some parts of the cell membrane and other structures of cells. Some fatty acids are changed into glucose, glycogen and amino acids. Fatty acids not needed by the body will be kept in special cells located under our skin, inside the abdomen, in the hips and thighs. Since it is also kept in the kidneys and the heart, the efficiency of those organs will be reduced.
AMINO ACIDS acquired from food will be transformed into proteins. These proteins are used as building elements for cells and other tissues, to produce new cells and assist body growth. Our body can use fats and proteins as an energy source when not enough carbohydrates are available. Unused proteins will be changed in the liver into fat and kept in body tissue. When proteins are changed into fat, amino acids will be produced as by-products. Some of these are dangerous to the liver and kidneys. Our body will have serious problems if we lack protein nutrients because by the time changes in the chemical processes are happening, cells receive only a protein enzyme.
The indigestible food parts will move into the large intestine. Cells inside the large intestine wall are able to absorb water, minerals and vitamins from the waste food and move it into the blood. The waste food then moves to the rectum and finally the anus. The anus has is a very strong ring muscle and used to pass fecal matter from the body. Researchers found that food we eat will move through the digestive system and reach the rectum 12 hours after consumption. The waste food will be in the rectum until it is full then a defecation feeling occurs and the waste is expulsed.