Subject Physiology

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Jun 07, 2018

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GASTROINTESTINAL TRACT

1.       Site of absorption of iron: Duodenum

2.       Intrinsic factor is secreted by: Oxyntic/ parietal cells

3.       HCl is secreted by: Oxyntic/ parietal cells

4.       Gastrin is secreted by: G cells of stomach, duodenum etc.

5.       Action of gastrin:

a.       Stimulates secretion of gastric juice,

b.     Increases gastric motility etc.

6.       Action of secretin:

a.       Stimulates secretion of watery, alkaline & pancreatic secretions, Inhibit gastric secretion,

b.     Causes contraction of pyloric sphincter,

7.       Most potent stimulator of secretion of secretin is:Acidic chyme

8.       Action of cholecystokinin: Stimulates contraction of gallbladder

9.       CCK-PZ secretion is stimulated by: Proteins

10.   Gastric secretion is stimulated by:

a.       Gastrin,

b.     Histamine etc.

11.   Gastric phase of gastric secretion is mediated by: Hormones

12.   Intestinal motility is stimulated by:

a.       Distension,

b.     Acetylcholine etc.

13.   Fat is maximally absorbed in: Jejunum

14.   Calcium is maximally absorbed in: proximal intestine

15.   Electrolytes are absorbed in: Colon

16.   Effect of dietary fibres (e.g. pectin):

a.       Increases bulk of stool,

b.     Increases metabolism or sugar in GIT

17.   Largest reserve of energy in body: Fat

18.   Gastric lipase helps in digestion of: Fats

Indicator of malabsorption: Fat in stool (> 6 gms/ day) 

Auerbach’s plexus - regulate the movements of GIT.

Meissner’s plexus - regulate the secretory functions of GIT.

GIT -mouth TO  anus ,total  length -30 feet.

Volume of stomach

empty - 50 ml  

expand  - 4 liters.

gastric juice:

Volume: 1200 – 1500 ml / day.

Reaction: pH 0.9 – 1.2.

Specific gravity: 1.002 – 1.004

Enzymes-

Pepsinogens -  proteolytic enzyme

-  Pepsinogen is activated by HCl to pepsin 

gastric lipase -

- weak lipolytic enzyme becomes active only when pH is between 4 & 5. 

Gastrin -

secreted by G cells present in pyloric glands of stomach. 

Pancreatic Juice: -

Volume: 500 – 800 ml / day.

Reaction: pH 8 – 8.3.

Specific gravity: 1.010 – 1.018

Total volume of pancreatic secretion per day  -  2.5 liters. 

Most sensitive method for assessing pancreatic exocrine function - Secretin Stimulation Test.

principal site of iron absorption -  Duodenum 

only organ that contains Trypsinogen -  Pancreas 

Bile 

- Most potent stimulus for bile secretion - bile salt.

- Best stimulus for CCK secretion - Fat

Properties of Bile:

• Volume: 800 – 1200 ml / day
• Reaction: alkaline
• pH: 8 – 8.6

Composition of Bile:

• Water: 97.6%
• Solids: 2.4%

Functions of bile salts:

• Emulsification of fats, due to emulsification, fat globules are broken down into minute particles.

•  Prevention of gall stone formation
  
• . Stimulate the secretion of bile from liver

succus entericus:-

• Proteolytic enzymes: peptidases – amino peptidases, dipeptidase & tripeptidase.
• .Lipase & enterokinase
• Amylolytic enzymes: sucrase, maltase, isomaltase, lactase, dextrase & trehalase
  

Properties of succus entericus:

• Volume: 1800 ml / day

• pH: 8 – 8.3

Vomiting center - bilaterally in medulla oblongata 

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