Functions of Carbohydrates
The most important function of carbohydrates is to provide energy to the body. They are also structural components of tissues. Carbohydrates are important in the regulation of fat metabolism, protein sparing functions in the digestive tract.
1) Structural components of cells:
Carbohydrates serves as an important structural material in some animals and plants. Carbohydrates constitutes the cellulose frame work.
2) Major source of energy:
Carbohydrates are essential to life. Almost all animals use them as respiratory fuels. Breakdown of a gram of carbohydrate yields four calories of energy. Glucose supplies the immediate energy needed by other nervous tissue. Lack of glucose or of oxygen for its metabolism leads to rapid damage to brain.
3) Storage substance of potential energy:
Carbohydrates, is stored in the body in the form of glycogen. The glycogen, stored in liver, controls glucose level in the blood. In plants, starch is the storage substance.
4)Regulation of fat metabolism:
Some carbohydrates are essential for the normal oxidation of fats. If carbohydrates are restricted in the diet, there is more rapid metabolization of fats. This results in the accumulation of incompletely oxidized intermediate products leading to keto sis. This is common in uncontrolled diabetes mellitus.
5) Protein sparing function:
As long as carbohydrates are present in the body, it is used as a source of energy. If it is not supplied in required amount, fat and then protein will be utilized as a source of energy. This is known as protein sparing function.
6) Role in gastrointestinal function:
Lactose promotes the growth of desirable bacteria in the small intestine. These bacteria synthesize certain B-complex vitamin. Lactose also increases calcium absorption.
7) Key role in metabolism:
Carbohydrates play a key role in the metabolism of amino acids and fatty acids.
8) Cell recognition: The glycoproteins, oligosaccharides present in the cell membrane serve as identifiers that assist the cells in their recognition of each other.
9) Supportive function:
Cellulose in plants and chondroitin sulfate in bone tissue offer supportive function.
10) Biological lubricants:
High viscosity and mucous for their role as biological lubricating material for protection of the cell surface. They protect the friction surfaces such as blood vessels, urogenital tracts, digestive tract, mucous membranes of the nose, trachea, bronchus, joints, etc. against mechanical damage.
Extracellular damage like mucopolysaccharides impart mechanical strength to the internal organs against compression and vibration. In aquatic plants, they are responsible for strength and resistance against hydraulic shocks.
11) Biological cement:
Acidic heteropolysaccharides such as hyaluronic acid function as inter-cellular cementing substances.
12) Osmotic and ionic regulation:
Acidic heteropolysaccharides, owing to their high hydrophilicity and negative charge, can retain large amounts of water and cations. For example, hyaluronic acid is an extremely hydrophilic polysaccharide. It controls the extracellular osmotic pressure by binding extracellular water and cations. Acting as an osmometer, this acid impedes excessive accumulation of free water in the extracellular space.
13) Co factors:
Certain heteropolysaccharides such as hepatrin and heparin sulfate function as enzyme co-factors.
Heparin elicits the activity of the enzyme proteins for which, it acts as a cofactor. Therefore, heparin exhibits an anticoagulative function and in antilipmic function.
Dermatan sulphate found in the aorta, also possesses anticoagulative properties.
14) Anticoagulants:
Heparin and synthetic sulphated polysaccharides are widely used as anticoagulants and antiatherosclerotic drugs( preventing the deposition of lipids in vessels).