Monday, 11 July 2016

SUPPLY OF PROTEIN TO THE BODY

DEFINITION: Protein can be defined as an organic compound composed of carbon , iron, hydrogen, oxygen, nitrogen and other element such as phosphorous and sulfur.


CLASSIFICATION OF PROTEIN
Protein are classified into animal and plant proteins. Animal protein are referred to as complete or first class protein because they contain full range of  the eight essential amino acids.

                          Plant protein or vegetable protein are referred to as partial/incomplete or protein of low biological value because their protein do not contain the full range of the eight essential amino acids. For example, the protein of cereal/grain (e.g. maize) is deficient in essential amino acid Lysine, while the protein found in legumes such as the soya bean is relatively low in methionine. The value of each of these foods is therefore enhanced if eaten as cereal-legume mixture , thereby providing the whole range of essential amino acids.

FOOD SOURCES OF PROTEIN

ANIMAL PROTEIN: Meat , fish , shellfish , eggs, cheese , milk, yogurt, snail, edible insects etc.
PLANT PROTEIN: Groundnut, melon seed , locust bean seed, beans, peas, lentis, soya bean etc.

FUNCTIONS OF PROTEINS
  • They are needed for the growth and development of tissue cell from birth until growth stops.
  • They are important for the repair and renewal of the tissues cell which constantly undergo wear and tear e.g the sole of the feet , nails , hair and skin.
  • They are needed for the formation of enzyme, hormones, antibodies , hemoglobin and antitoxins.
  • They help to control alkalinity of blood and the osmotic pressure in the blood vessels.
  • They can be used for the production energy if insufficient  energy foods are eaten .
DAILY REQUIREMENT OF PROTEIN 
       The daily requirement of protein for an adult is 60-90g while the daily requirement for children up to eighteen years is 20-70g.

DIGESTION AND ABSORPTION OF PROTEIN
         The chemical digestion of protein in the stomach with the conversion of pepsinogen by hydrochloric acid into the enzyme pepsin.
          Caseinogen which is the protein in milk is converted by another enzyme called rennin into casein. Protein then converts all protein and casein into peptones.

          In the intestine, Enterokinase of the intestine juice convert pep tone into peptides and polypeptides. Further down the intestine , peptidase of the intestinal juice convert peptide and polypeptide to amino-acids . The amino-acids are then conveyed via the portal circulation to the liver. For their metabolism , amino acid pass from the liver into the general circulation and in this way reach the various cell which utilize them. Excess amino acids are deaminated, that is the nitrogenous content is removed and converted into urea for elimination in the urine. The remaining part is converted to glucose and use to provide energy and heat.
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