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Physiology of Gastrointestinal System - last moment revision for competitive exam

Wednesday, 4 January 2017


Physiology of Gastrointestinal System for last moment revision

The length of Alimentary Canal - 30ft (9m)

Length of adult Oesophagus is 25 cm

GIT - Mouth, pharynx, oesophagus, stomach, small intestine, large intestine

Accessory organs - salivary glands, liver, gallbladder and pancreas

Serosal layer not seen in Rectum

1Kg solid & 1-2 L liquids consumes per day

GIT receives 9L water /day

Total GI secretion 8L/day

Mechanical and Chemical Digestion begins in Mouth 

Largest salivary gland is Parotid gland, but 70% saliva production by submaxillary gland

K maximum in saliva > colonic/rectal fluid

Protein digestion begins in Stomach

No proteolytic enzyme in saliva

Stomach volume 50ml(empty), expandable upto 4L

Gastric Juice pH 0.9 - 1.2

HCL by Parietal cells or oxyntic cells

Pepsin by Chief cells

Gastric lipase active only when pH 4-5

Proteolysis begins in Stomach

No Saccharolytic enzyme in gastric juice

Trypsinogen(only one organ) pancreas

Most alkaline secretion - Brunner’s gland mucous > Hepatic Bile > Pancreatic Juice

Stomach absorbs Alcohol (20%) & Aspirin

Iron absorption at Duodenum

Max water reabsorption by Jejunum

Vit B12 & Bile salt absorption by terminal ileum

Absorption: Galactose > Glucose > Fructose > Mannose

Insulin has no effect on absorption of glucose in GIT

Large Intestine receives 500ml indigestible food/day

Faeces Volume: 150ml

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