1. Digestion ,Absorption ,& metabolism

2. Digestion in mouth

3. -digestion
- body food component travel together ,through GIT into the cell.
*basic principles of 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.
-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.

4. 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 .
**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

5. 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.
-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 .

6. *factors affect salivary secretion :-
** chemical or secretary digestion : 3 pairs of salivary glands ,parotid ,sub-maxillary , sub-lingual ,secrete salivary amylase this enzyme is specific for starch digestion .
*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

7. 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 .

8. -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 .

9. -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 .

13. Problems related to food digestion
Incomplete digestion
Lack of digestive enzymes
Gallstones

14. 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 .

15. Large intestine : final absorption & waste elimination .
*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.
Mineral absorption :
Essential minerals as Na & K go to blood stream .

16. 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).

17. Villus epithelium epithelial cells Capillary network lacteal
Villi – plural of villus

18. 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 .
*non CHO sources:
-from protein & fat .

19. -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.

20. Glucose converted to glycogen , stored in liver 7 muscle tissue .
-normal blood glucose level mg \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 .

21. **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

22. b-blood sugar raising hormones :
*1-glycogen -produced from alpha cells of pancreas, opposite action of insulin .
*2-somatostatin:
-delta cells of pancreas .
-anti insulin effect .
*3-steroid hormones :
-secreted from adrenal gland .
-anti insulin effect .

23. *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

24. -2-lipid metabolism :
*liver &muscle responsible for fat production& fat breakdown .
*lipo-protein comes from absorption of protein &fat from intestine .
*GH, ACTH, TSH increase release of fatty acid /
*cortisone & hydro-cortisone increase fatty acid production .
*Epinephrine ,non epinephrine ,thyroxin ,insulin * decrease cholesterol secretion . -

25. 3-protein metabolism
: -responsible about tissue building ,&tissue break down .
-GH,gonadotrophine hormone ,thyroxin participate in tissue anabolism tissue catabolism .
-break down of protein give amino acid .
-amino acid divided to :
*1 nitrogen ,end product is ammonia passed in urine & stool .
*2non nitrogen residue (ketoacid).
*3control agent (co-enzymes),enter in metabolic process .