Proteins PDF

Proteins Proteins have long been recognized as fundamental structural elements of every cell of the body\] Specific proteins and protein derivatives have been recognized as functional elements in certain specialized cells glandular secretion, enzymes and hormones. Proteins in natural foods differ...

Proteins Proteins have long been recognized as fundamental structural elements of every cell of the body\] Specific proteins and protein derivatives have been recognized as functional elements in certain specialized cells glandular secretion, enzymes and hormones. Proteins in natural foods differ widely in the number and theproportion of the 22 or more amino acids. A good quality or a alcomplete protein i is the one that supplies growth and maintenance. In general all proteins from animal source, such as meat, poultry, fish, eggs, milk and milk products provide good quality proteins Call the essential amino acidsin sufficient quantities and in proper ratio for normal Source of proteins Milk products such as cheese, ice cream all derive their protein from milk. Meat, poultry, and fish are all forms of animal tissues Eggs are in a class by themselves a protein food of high nutritive value. Vegetables are poor source of protein Legumes provide more than 4 or 6 percent. They are listed as Meat alternates i in the four-food group chart because they provide One of the better quality plant proteins Bread and cereals make an important contribution to the protein of the diet, the protein of uncooked grain ranges (7 to 14 percent Digestion and absorption of protein The digestion of protein in the alimentary tract is accomplished by the Action of several proteolytic enzymes in the gastric, pancreatic and Intestinal juices. Any of these enzymes that have the power to attack Native proteins must be secreted in an inactive form to prevent Damage to the tissues where they are formed. Types of enzymes Pepsinogen is secreted by the gastric juice and activated by the Hydrochloric acid Trypsinogen is secreted by pancreatic juice and activated by entropeptidase Chemotrypsinogen is secreted by pancreatic juice and activated By the active tripsin Summary of protein digestion Site of action Stomach - Small intestine Protein Protein Polypeptides Polypeptide dipeptides Enzyme Pepsin in acid. Trypsin chemotrypsin بیند Peptidase (secreted by mucosal cells of small intestine ↓ Enter portal blood Liver ↓ ↓ Body tissues END PRODUCT Large peptide poly peptides ↓↓Polypeptides Dipepetides Amino acids Peptides Amino Acids Portal The Amino Acid Pool The amino acids from the food or from the body tissues enter a common pool, which is drawn upon for the synthesis of proteins, hormones, enzymes, blood protein and nucleic acids, or some of the amino acids are degraded for energy needs. Proteins are absorbed as amino acids Ideally, they are used toحول الطاقة or maintain body proteins. If carbohydrates and fats are not meeting the energy needs of the body, amino acids can be used to Danger of the weaning period The weaning period is fraught with dangers for a large proportion of the world\'s children and nutritional disorders are common at this time of life. In the West a general awareness of the nutritional needs of the weanling, together with the ability of the average family to provide the necessary foods, have helped to remove most of the dangers of the weaning period. In the peasant society of developing countries, however, parents are generally are unaware of the dietary needs of children, and several customs associated with weaning are likely to give rise tolnutritional deficiencies) Protein energy malnutrition (PEM) PEM is today the most serious nutritional problem in Africa and other developing countries. Its two clinical forms are Kwashiorkor The diseases occur mostly in children between one and three years Of age, after they have been taken of the breast. Although there is no final clarity about the etiology of kwashiorkor in biomedical terms, it is nevertheless, clear that it is related to nutritional deficiencies. Therefore, all factors that could possibly contribute to the child malnutrition in general should be avoided. These include: Seasonal food shortage Unfavorable family condition, Inadequate water supply and sanitary facilities, Certain traditional attitudes during pregnancy, prenatal period Breast-feeding and weaning periods, and All infectious diseases, which generally reduce immunity. Other diseases may sometime play an important role in precipitating The onset of kwashiorkor in already malnourished child. E.g. Gastrointestinal tract infection Diarrhea Intestinal worms share the diet and cause other ill health and Poor appetite Constipation Childhood diseases such as measles, whooping cough, etc, Signs and symptoms of kwashiorkor Growth failure occurs always Wasting of muscle is also typical but may not be evident because Of edema There may be mental change Hair and skin color change Diarrhea and vomiting Sign of other micronutrient deficiencies **Nutritional** **Marasmus**- There is ✓-Irritability, restlessness and diarrhea are frequent -Many infants are hungry, but some anorexic There are little or no subcutaneous fats The weight is much below the standard for age. Temperature may be subnormal. The abdomen may be shrunken or distended with gas. Because of the thinness of the abdominal wall, peristalsis may be easily visible. The muscles are weak and atrophic and this makes the limbs appear as skin and bone) Evidence of vitamin deficiencies may or may not be found