3. Digestion ,Absorption ,& metabolism
- body food component travel together ,through GIT into the cell.
*basic principles of digestion:

4. -digestion:
prepares the food for the body use ,under effect of muscular &chemical reaction.
-muscular layer of the elementary system (serosa,submucosa,&mucosa),&fiber layer longitudinal or circular layer, help in the movement of food &push it forward ,this movement called peristalsis.

5. -chyme:fluid secreted by GIT to help in digestion .
-the action of food is under control of nervous system at GIT wall called intra-mural nervous plexus extend from esophagus to anus responsible for regulation of the rate &intensity of muscle contraction with coordination in various movement.

6. *definition of digestion:
-the process of break down food to release its nutrients for absorption & transport to the cell for use in the body .
*peristalsis:
Wave like progression of contraction & relaxation .

7. **types of GIT secretion:
-1-Enzymes: chemical action e.g. lipase ,amylase .
-2-hydro-choloric acid & buffer ions : necessary ph .
-3-mucous:protect the inside wall tissue of GIT,lubricate &facilitate food mass passage .
-4-water & electrolyte.

8. Mouth& esophagus: preparation &delivery:
-1*mastication:
-chewing break-down food into smaller particles by teeth & jaw muscle with tongue.
-2*swallowing:
-occur at mouth & pharynx.
-rapid less than one second .
-coordination &swallowing comes from(swallowing centre area) in the brain stem.

9. -gravity &muscle at the base of the tongue ,help in the movement of the food down to esophagus ,in the up-right position .
-in the stomach food enter by opening of the sphincter to prevent reflux ,&occurrence of heart burn .
** chemical or secretary digestion : 3 pairs of salivary glands ,parotid ,sub-maxillary , sub-lingual ,secrete salivary amylase this enzyme is specific for starch digestion

10. - :

11. *factors affect salivary secretion :-
1-sight . 2-smell. 3-taste. 4-touch. 5-thought of like & dis-like of food.
-normal range of daily saliva secretion between ML,pH neutral

12. -stomach : storage & initial digestive process .
-as the food enter the stomach ,the muscle of the stomach mix the food ,storage ,&control emptying .
-when the food mixed with chyme ,the pyloric sphincter constrict & relax for control of emptying at duodenum.
**types of stomach secretion :
a-acid : HCL hydro chloric acid .
b-mucous : protect the wall of lining stomach & lubricant .
c- enzymes: pepsin ,break down of protein (pepsinogen converted to pepsin under HCL secretion ),gastric lipase for fat , rennin in child-hood aid in co-agulation of milk ,but absent in adult .

13. الخضار

14. -control process of gastric secretion under effect of :
1-nervous stimulus in response to sense ,ingested food & emotions ,e.g. anger & hostility increase secretion , while fear & depression ,decrease secretion .
2-hormonal stimulus in response to entrance of food into stomach ,e.g. gastric enterogastrone

15. -small intestine: major digestion & absorption
-under control of nervous plexuses or hormonal stimulation ,the wall stretch from pressure of food .
-small intestine is chemical digestion by secrete large number of enzymes & assistance of pancreatic enzyme .

17. ** types of secretion : a- enzymes .
b-mucous from glands near the duodenum to protect the mucosa of intestine .
c-hormones that stimulate pancreas to secrete alkaline juice .
d-bile secreted from liver &store by gall bladder to dissolve fat .

18. Absorption -end product of digestion .
-CHO (glucose, fructose, galactose ).
-fat (fatty acid ,glycerides).
-protein (amino-acid ).
-villi: finger like projection seen under microscope help in absorption

19. *Routes of absorption :
-proteins &CHO become water soluble ,enter to blood stream ,go to liver ,&other tissue ,while fat is not water soluble ,bile secreted in intestine ,help in digestion of fat .
Large intestine : final absorption & waste elimination .
Water absorption take side at colon .
As much as 25% of meal may remain in rectum up to 7 hrs

20. الفواكه

21. Mineral absorption : Essential minerals as Na & K go to blood stream .
Bacteria in the colon syntheses vit K .
-intestinal bacteria affect color & odor of the stool .
Brown stool comes from bile pigment .
Intestinal gas or flatus produced by bacteria .
Fiber does not digested so it contribute to form bulk of the stool .
Normal feces contain 75% water, 25% solids .
Solids ( fiber ,bacteria ,minerals ,small amount of fat , mucous).

22. Metabolism 1-CHO metabolism :
Source of blood glucose *CHO &non CHO substances *
*CHO sources:
-dietary starch & sugars .
-glycogen from liver & muscle tissue , by hydrolysis glycogen to glucose .

24. *non CHO sources: -from protein & fat . -indirect source of glucose .
*in case of protein glycogenic amino-acid could be used in energy , if insufficient CHO .
*in case of fat broken to fatty acid &glycerol ,glycerol converted to glycogen in the liver .
-the process of production of glucose from protein or fat is called gluconeogenesis.

25. -normal blood glucose level 70-120mg \dl.
1- energy production .
2-energy storage :
Glucose converted to glycogen , stored in liver 7 muscle tissue .
Excess glucose converted to fat & stored in adipose tissue (fat tissue ).
3- glucose product :
Glucose enter in DNA &RNA building .

26. الحمضيات

27. **hormonal controls -blood sugar lowering hormones
a- insulin decrease blood sugar ,produced by beta cells in the pancreas.
-convert glucose in the liver to glycogen by process called glycogen sis .
-convert glucose to fat & storage in adipose tissue .
b-blood sugar raising hormones :
*1-glycogen -produced from alpha cells of pancreas, opposite action of insulin .

28. *2-somatostatin:
-delta cells of pancreas .
-anti insulin effect
*3-steroid hormones :
-secreted from adrenal gland .

29. *4-Epinephrine : -secreted from adrenal medulla .
-break down glycogen in the liver to glucose .
*5-grouth hormone :
-secreted from anterior pituitary gland .
-anti insulin effect .
*6-thyroxine :
-increase glucose absorption from intestine