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Parts of the GIT and their Functions

Mention the different parts of parts of Gastrointestinal Tract with the help of a diagram and briefly explain their functions.
Parts of the GIT
1.    Mouth
2.    Pharynx
3.    Esophagus
4.    Stomach
5.    Small intestine - Duodenum, Jejunum, Ileum
6.    Large intestine - Caecum, ascending colon, transverse colon, descending colon, Sigmoid colon
7.    Rectum, anal canal and anus

Functions of mouth
a)    Ingestion of food materials
b)    Chewing and mixing of food with saliva
c)    Appreciation of the taste of food
d)    Swallowing of food

Functions of pharynx
a.    Taste of food
b.    Swallowing of food

Function of esophagus
Transport of food from pharynx to stomach during the act of swallowing

Functions of stomach
a.    Storage function:  acts as a reservoir for food
b.    Mechanical function : by movements of stomach,  the  food gets mixed with gastrid juice and gets converted into chyme.
c.    Stomach propels the  food into the  intestine
d.    Digestive function : Gastric glands secrete gastric juice which contain digestive enzymes. The enzymes digest the  food, The HCl present in the stomach hydrolyses the food.
e.    Absorptive function : Stomach absorbs water, glucose, salin, alcohol and some drugs
f.    Protective function: (Bacteriolytic) HCl present in the gastric juice destroys many  types of bacteria entering the body with food.
g.    Haemopoietic functions : Gastric mucosa seretes intrinsic factor for maturation of the RBCs
h.    Excretory function : Many substances  likke drugs, heavy metal and toxins are excreted through  gastric juice
Functions of Small  Intestine
a.    Mechanical function : Peristaltic movements of small intestine  help mixing of chyme  with digestive juices like succus entericus and pancreatic juices.
b.    Secretory function : Small intestine secretes succus entericus and GI hormones
c.    Hormonal  functions : Small intestine secretes hormones like enterogastrin, secretin, cholecystokinin.
d.    Digestive function :  The digestion of food is completed in the small intestine by the enzymes present in succus entericus   and pancreatic juice.
e.    Activator function : Small intestine secretes enterokinin which activates trypsinogen into trypsin
f.    Haemopoietic function   Small intestine absorbs intrinsic factor which is necessary fo the  absorption of Vit B12.  It is necessary for maturationof  RBCs.
g.    Hydrolytic functions : Succus entericus provides water and helps in all hydrolytic process of enzymatic reactions of foods
h.    Absorptive function : The following are absorbed by  the small intestine : digested products of carbohydrates, proteins, fats, minerals, vitamins, water and other nutrients.

Functions of Large intestine
Secretory functions : Large Intestine secretes mucin, inorganic substances like chlorides and bicarbonates
Synthetic function  the bacterial flora in L.I. synthesize Folic acid, Vitamin B12 and Vitamin K
Absorbtive function : In large intestine water glucose, alcohol, some drugs, anesthetic agents, sedatives steroids are absorbed
Excretory function : L. I. excretes heavy metals like Hg, Pb, Bi, Ar through faeces
After absorption of nutrients, water and other  substances, the  unwanted substances form faeces which is excreted out.

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