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PHYSIOLOGY-DIGESTION & ABSORPTION(Pt1_1/2) - Coggle Diagram
PHYSIOLOGY-DIGESTION & ABSORPTION(Pt1_1/2)
Digestion
Chemical Process
-enzymes
Mechanical Process
-chewing & peristalsis movement
Human gut
:90-97% efficiency excl. plant origin carb(dietary fibre)-no enzymes
Brush Border
valvulae connivates
- folds in the mucosa of small intestines from 2nd part of duodenum.
Large & thick
in duodenum & jejunum , decrease in size distally in the ileum. Disappear in the lower part of ileum.
Function
:Slow passage of food & ↑ intestinal surface for absorption
Valvulae conivates covered with
Villi
>>Villi covered with
microvilli
that absorbs the nutrients & digestive products from the chyme
200 – 300 m2 absorptive surface for nutrients
Enterocytes
-3-5 days lifespan>migrate from crypts to top of villi>then sloughed off>fall off into intestinal lumen
Hight Turnover of enterocytes
>vulnerable to nutrient def.,toxins,food allergy,blood supply damage,malnutrition
Mouth
Lubrication via saliva(1.5l/day)
Enzymatic digestion:
Linguinal lipase
-TG>>DG
Deactivated in stomach
Amylase
-starch>>dextrins& maltose
teeth grind food>small particles
Bolus
>swallowed voluntarily , peristalsis in the oesophagus
Stomach
HCL, Pepsinogen ,gastric lipase,mucus ,intrinsic factor:B12
Less absorption
dilution
by fluids(2-2,5l/d)
Germicidal action
-acidic conc.(pH1-4) kills the microorganisms(some may enter Small intestines)
Pyloric sphincher
>controls the emptying of acidic chyme to small int.
Emptying
=1-3 hrs, carbs(rapid),protein, fat, fibre food , energy dense(slowly)
Small Intestine
Most Digestion & secretions:proteolytic enzymes,pancreatic enzyme,bile salts,Pancreatic lipase,SI enzymes>
duodenum
Digestion & absorption-
Jejunum
Duodenum(0.5),jejenum(2-3m),ileum(3-4)
Fluids & electrolytes, B12, Bile reabsorbed in
ileum
3-8 hrs to move through SI into the
iliocoecal valve
(control movement in colon)
Large intestine
Bicarbonate secretion
neutralizes acidity
absorption=2L, excreted=150 ml
1.5 long(coecum, colon,rectum , anal tract)
Bacterial fermentation
of protein & carbs
Vit. K produced
18-72hrs ,
stool
=sloughed cells , GIT secretions,bacteria,mucous,undigested food