Proteins

essential life substance of all living matter . act as structural unit to build our bodies . specific structural chemical units amino acids amino [alkaline substance carbon, hydrogen ,o2& NH2. Essential amino acid are 9 in number : Significant in our diet . The body unable to syntheses these 9 amino acid so get it from our food

*types of protein : 1-myosin : found in muscle ,has role in contraction & relaxation of muscle . 2-collagen: has role in strength of bone . 3-hemoglobin attach with iron in the RBCs ,help in carrying o2. 4- albumin : major plasma protein . 5- globulin : alpha beta gamma globulin ,act as antibodies of immuno system

N.B: complete protein foods comes from animal source as egg ,milk, cheese , meat . Incomplete proteins food : plant food ,deficient of one or more essential amino acid , mostly of plant origin grains ,legumes ,nuts seeds . Mixture of protein animals & plant animals give balance in the ratio of amino acid .

Functions of protein : A- growth & tissue building maintenance . B- specific physiological roles : Some types of amino acid used as neurotransmitter substance in the brain . Aid in metabolic hormones as thyroxin C- available energy

**digestion ,absorption & metabolism of proteins: @ mouth : mechanical break down of food by chewing food mix it with saliva ,push it to stomach . @ stomach : break down of protein to small particles by secreting enzymes pepsin ,HCL ** provide acidic media to convert pepsinogen to pepsin . Rennin : found in infancy & childhood to digest milk , rennin prevent too rapid passage of food from the child stomach . @ small intestine :alkaline media in the intestine ,also pancreatic secretion like trypsin & chemotropism.

** absorption of amino acid : the end product of protein digestion is the amino acid ,which is water soluble so absorption occur through blood stream . absorption of amino acid at duodenum carried by pyridoxine [ vit B 6 ]. Metabolism of protein : Important protein balance is anabolism & catabolism . Protein more found in liver ,pancreas ,kidney & plasma lower protein in the brain ,muscle ,& skin .

Tissue catabolism occur in case of starvation & aging process { tissue break down are exceed than tissue building } . Destruction of protein resulted in ; urea , uric acid ,ammonia . Protein requirement : Protein is essential nutrient . Under develop countries protein energy malnutrition . Primary role of amino acid important for growth ,& maintenance of tissue .

Age ,body size ,general physical state has role in protein requirement . Disease increase need of protein diet especially in case of fever . Traumatic injury ,post surgical state require protein for wound healing . In case of burn , the need of protein increased . Protein should be adequate in quantity & quality. The need of protein increase in case of pregnancy .