INTESTINE INTESTINAL JUICE Dr Pushpa Lata Sachan Associate

INTESTINE & INTESTINAL JUICE Dr Pushpa Lata Sachan Associate Prof. Dept. Physiology CIMS & H

SMALL INTESTINE & INTESTINAL JUICE �Small Intestine: - from pyloric sphincter ‘up to Ileocecal value. �. �Length = 300 cm, – Diameter = Smaller than large intestine. � 3. Part : - (1. )Duodenum (2. ) Jejunum, & (3. ) Ileum

Histology All 4 layers �(1)Serosa �(2. ) Longitudinal & Circular muscles layer, �(3) Sub mucosa, � (4) mucosa, with Intestinal glands. �[with Meissen’s & myenteric (i. e. intrinsic) nerve plexuses] � Villi - -Lined by enterocytes �Enterocytes – show microvilli. �Both increases surface area for absorption. Contain lacteal and also blood vessels.

�Both increase surface area for absorption � Contain Lacteal (central channel) & also blood vessel. �Intestinal glands, or crypts of lieberkuhan – - Simple tubular glands - Opened into lumen of intestine , between villi. - Secrets intestinal juice or, succus entericus

� intestinal juice enzymes, carbohydrates , proteins and fat. �Intestinal juice (Succus- Entericus) -Volume 1800 ml/day - PH – 8. 3 -Reaction -Alkaline - for digestion of

�Composition of intestinal juice - (A) Water 99. 5 % - (B) Inorganic substances – e. g –Na , K Po 4, Cl, So 4, Hco 3, ect - (C) Organic substances – - (a) Mucus secreted by goblet cells and brunners glands. - (b) Intrinsic factor – Secreted by Argentaffin –cells.

�(c ) Enzymes for digestion – Secreted by – enterocytes cells. �(1) Proteolytic enzyme – Peptidases -Aminopeptidases -Dipeptidases Tripeptidases (2) Amylolytic enzymes – Disaccharidases - Sucrase - Maltase - Lactase , etc.

(3) –Lipolytic –enzymes – Intestinal Lipase (4) – Enterokinase Functions of Intestinal Juice – (A) Digestive Function – (1) Carbohydrate Digestion – by Amylolytic – enzymes. Maltase -Maltose Glucose (2 molecules)

Sucrose Lactose Dextrin, Maltose& Maltriose Sucrase Lactase Glucose and Fructose Glucose and Galactose Glucose (Dextrinase)

�Trehalose Trehalase Glucose �So Disaccharides ( Enzymes) � Monosaccharides (2) –Protein – Digestion - by proteolytic enzyme

�Polypeptides ( Aminopeptidases) Aminoacids �Tripeptides ( Tripeptidase) Amino-acids �Dipeptides (Dipeptidases) Aminoacids -So Peptides (Enzymes) Aminoacids

3 -Fat Digestion by lipolytic enzymes �Triglycerides Intestinal -Fatty -acids (Lipase ) B –Activator- functions – -Trypsinogen (Activation) Trypsin Enterokinase of intestinal- juice Trypsin – Activates other pancreatic enzyme.

�(C) Protective Function – - Mucus , of intestinal juice protects the intestinal wall , from acid chyme, and prevents intestinal ulcer. (D. )Haemopoietic - Function: � Intrinsic Factor of Intestinal juice plays important role in erythropoiesis & maturation of RBCS - by helping in absorption of vit. B 12.

�(E. )Hydrolytic - Function : - Intestinal juice provides water ; which help in all the hydrolytic processes of enzymatic reactions for the digestion of various food stuffs.

FUNCTIONS OF SMALL INTESTINE �Digestive functions : �Activator functions : - (Functions of intestinal juice �Protective functions: - or Succus -entericus) �Haemopoeitic functions: �Hydrolytic functions: -

FUNCTIONS OF SMALL INTESTINE �Absorptive function : - Absorption of digested products of carbohydrates , proteins , fats �Also absorption of vitamins , mineral , water , drugs etc. �With the help of – villi & microvilli.

�Mechanical functions: - by mixing movements & also by peristalsis - helps in movements of foods (chyme). �Secretory functions : - -Secretion of Intestinal juice , Enterokinase & G. I. T. hormones.

Ø Hormonal functions : - by secreting G. I. T. hormones which help in movements & secretions of enzymes etc. Ø e. g. – �- Entero Gastrone �- Secretin �-Cholecystokin , pancreozymin (C. C. K. - P. Z. ) �-G. I. P. �-V. I. P. �-Glucagon, - Somatostatin , motilin , substance P, ect.

FUNCTIONS OF LARGE INTESTINE: �Absorptive – functions: - -Help in absorption of water , electrolytes , glucose , alcohol & some drugs like anesthetics , sedatives & steroids etc. �Secretory – functions: - Secretion of mucin , chlorides & bicarbonates etc.

�Synthetic – Functions: - Synthesis of vit. B 12, folic acid & vit K; with the help of its bacterial flora. �Formation of faeces (stool ): - - After absorption of water , nutrients & other Substances.

�Excretory functions : �Excretion of faeces which are unwanted substances �Also excretion of heavy metals, like Hg, Pb , Bi, As, etc. though faces.