1. Lec GIT March 14

2. Stomach Objectives 1.Physiological anatomy 2.blood supply
3.innervation
4.Gastic secretion

3. Physiological Anatomy
The stomach is a j – shaped.
( rugae) stomach to change size and adapt its
content.
Anatomically the stomach is divided into
a. Cardiac region
b. Fundic---filled with swallowed air
c. Body region
d. The pyloric region ( antrum)

6. Blood and lymphatic supply.
Gastric Innervation----para & symp

7. Gastric Secretion

8. Composition of normal gastric juice (fasting state
hydrochloric acid----
intrinsic factor
pepsinogen
mucus,
hormone gastrin
cations and ( such as Na+ ,K+ , Mg2+ , H+ )
, anions ( Cl- , HCO3- , So42-,Hpo42-)
digestive enzymes

9. chief cells ----- pepesinogen.
Oxyntic Glands HCL ,intrinsic factor, pepsinogen, , and mucus.
composed of three types cells :
chief cells pepesinogen.
b. parietal ( or oxyntic cells ) -----HCl and intrinsic factor
c. mucous neck cells----- mucus .

11. Basic mechanism of HCL Secretion
HCL--150–160 mmol/L in amounts of 1–2 L/day
PH is 0.8 highly acidic
Basic steps for HCl formation

13. Q: Any factor inhibits the enzyme carbonic acid anhydrase (CA) or H-K ATPase will abolish the secretion of HCL from oxyntic cells. Why?

14. Postprandial(enteroprandial) alkaline tide:.
Increase in H secretion ----increase HCO3-
To blood -----increase PH ( Alkaline)---alkaline urine

15. Q.explain why a slight increase in blood PH may occur following a heavy meal?.

16. Stimulation of gastric acid secretion
Histamine: Acid secretion is stimulated by histamine via H2 receptors
acetylcholine . by acetylcholine via M3
muscarinic receptors
GASTRIN----GASTRIN RECEPTOS EITHER:
directly by gastrin receptors
indirectly ---- ECL cells---Gastrin is the major regulator of the ECL cells. .

19. 2.Pepsinogen
inactive precursor pepsinogen--- intragastric pH lower than active enzyme pepsin Pepsinogen detected in the plasma and in the urine, where it is called uropepsinogen 3.Intrinsic factor ----with dietary vitamin B absorption distal ileum,

20. 3. Intrinsic factor
Intrinsic factor is secreted by the parietal cells. It combines with dietary vitamin B12, forming a complex necessary for the absorption of the vitamin in the distal ileum.

21. 4.Surface Mucous Cells viscid mucus mucus alkaline. Lubrication
1 millimeter thick, thus providing a major shell of protection
Substances cause gastric irritation are : ethanol , vinegar , bile salts , aspirin , and other non steroidal anti – inflammatory drugs ( NSAIDs).

22. 4.Digestive Enzymes
Gelatinase---liquefies gelatin
. lingual lipase---for partial digestion of fats..
gastric lipase----for partial digestion of fats..

23. Pyloric Glands no parietal cells
mucus neck cells---mucus ,small amount of pepsinogen
Secrete hormones gastrin

25. Phases of Gastric Secretion
Cephalic phase .
. Gastric Phase .
Intestinal Phase

27. Cephalic phase before food enters the stomach
sight, thought----cerebral cortex----hypothalamus &MO---para.vagal---gastric secretion
smell,, or taste of food, tactile sensation ---hypo &MO-----Para. Vagal---gast.secre.
Loss of appetite –---gastric secretion
Account 20% of gastric secretion .

29. Gastric phase A.Distention ---1.vagovagal---MO—vagus--stomach
2. local enteric reflexes,
3.GRP---. gastrin SECRETION---acid secretion
Food ,caffein,low acid--- G – cells--gastrin secretion
B,stress,high acid ----gastric secretion

30. by vagal stimulation about 500ml of HCl is secret daily),while by gastrin release about 200ml /day is released

31. Q. What happens when Surgeon cuts the vagal nerve(parasympathetic cranial nerve) to the stomach

32. Intestinal phase 1.Entergastric inhibitory reflex :
1.myenteric nervous system
2.extrinsic sympathetic and vagus nerves-----inhibits gastric secretion
2.Hormonal . inhibitory hormones (VIP CCK,GIP,secretin)—inhibit gastric and motility secretion