Disorders of Digestive System

The inflammation of the intestinal tract is the most common ailment due to bacterial or viral infections. The infections are also caused by the parasites of the intestine like tape worm, round worm, thread worm, hook worm, pin worm, etc.

Jaundice: The liver is affected, skin and eyes turn yellow due to the deposit of bile pigments.

Vomiting : It is the ejection of stomach contents through the mouth. This reflex action is controlled by the vomit centre in the medulla. A feeling of nausea precedes vomiting.

Diarrhoea: The abnormal frequency of bowel movement and increased liquidity of the faecal discharge is known as diarrhoea. It reduces the absorption of food.

Constipation: In constipation, the faeces are retained within the rectum as the bowel movements occur irregularly.

Indigestion: In this condition, the food is not properly digested leading to a feeling of fullness. The causes of indigestion are inadequate enzyme secretion, anxiety, food poisoning, over eating and spicy food.

NUTRITIONAL REQUIREMENTS OF HUMANS

Energy Yielding Nutrients

Carbohydrates are used primarily as sources of chemical energy, to be either metabolised immediately as glucose or stored as glycogen.

The synthesis of glycogen is called glycogenesis.

The liver can store enough glycogen to maintain blood glucose level for several hours. Under acute starved conditions, the liver cells begin to convert fatty acids and the glycerol (digestive products of fat molecules) into glucose.

Such production of new glucose is known as gluconeogenesis. Proteins are used as structural components of tissues, as channels, transporters, regulatory molecules and enzymes.

Proteins can also be utilised as energy sources, when broken down to amino acids.

Out of the 20 amino acids identified so far as the constituents of proteins, 8 (10 in children) cannot be synthesised in human body.

These must be provided in the diet from outside are designated as essential amino acids.

Lipid (fat) molecules are especially suitable as concentrated energy reserves.

The fat cell of adipose tissues are often called the fat depot of body.

Triglycerides are used as fuel.

Human body is able to synthesise most of the lipids in enough quantity, except three polyunsaturated fats, such as linoleic, linolenic and arachidonic acids.

These essential fatty acids must be provided to the human body through diets.

Minerals and Vitamins

Both minerals and vitamins occur as small molecules and mostly, do not require digestion.

Minerals are ingested as salts dissolved in water or as part of organic compounds (food).

Still, a few of the minerals are absorbed with the aid of digestive Juices (like bile) and gastric juices.

Of the twenty-one essential minerals required by man, some are important for maintaining fluid balance whereas others help to regulate metabolism by acting as a component of enzymes.

Vitamins are essential for normal metabolism, growth and sound health.

Humans can synthesise vitamin A (retinol) with the help of plant pigment, carotene, which is available in yellow and green leafy vegetables.

Vitamin A forms retinal pigment of human eyes, such as rhodopsin of rod cells and iodopsin of cone cells.

Humans can also synthesise vitamin D (calciferol) in their skin in presence of ultra-violet rays. Although most animals can synthesise vitamin C from glucose, humans cannot; hence, they require it in their diet.

Nutritional Deficiencies and Disorders

Deficiencies of nutrients, like vitamins, minerals and proteins, in the food are related to specific disorders, diseases and abnormalities in humans.

Impairment of health due to improper intake of food or nutrients results in malnutrition.

Malnutrition is a term which covers problems of both undernutrition and overnutrition.

An individual or a group of individuals, may be undernourished due to non-availability of food, and hence, deficiency of minimum required food and nutrients.

In this situation of undernutrition, the intake of food is too insufficient to meet the needs for metabolic energy.

Consequently, the individual shall have to make up the shortfall by metabolising some molecules of its own body.

Excess intake of food and nutrients may cause a great deal of harm to the body.

The excess nutrients are stored as increased body mass. Such a situation is attributep as overnutrition.

Excess intake of saturated fats, like butter, ghee, vegetable oils, red meat, eggs, etc., often leads to hypercholesterolemia, a condition in which blood cholesterol content becomes abnormally high, ultimately leading to cardiac disorder.

Deposition of cholesterol on the walls of blood vessels stiffens the blood vessels and increases blood pressure.

Besides, excessive intake of calories (sugar, honey, ghee etc.) may produce overweight and obesity (excessive accumulation of fat in tissues), which is the most common form of overnutrition.

Very high intakes of minerals and fat-soluble vitamins (obtained from food sources alone) can be toxic.

This is because they are stored in the body.

With the exception of folic acid (women of child-bearing age), people who have well-balanced diet that supply enough energy, do not usually need to take dietary supplements.

But, if they do decide to take supplements, then they should follow the advice on the label to reduce the risk of an overdose.