Stomach physiology

2019

1. physiology of stomach & Duodenum Dr Sapan Kumar 1 st year PG General Surgery mkcg

2. Physiology of Stomach Quick Anatomy of Stomach Physiology of Stomach Function of Stomach Gastric secretion- Glands, Composition, Regulation, Phases GI motility & gastric emptying Peistalsis Gastrointestinal hormones Disorder of stomach

3. anatomy of stomach Stomach is the most dilated part of the gastrointestinal tract It lies upper left quadrant of abdominal cavity, occupying the epigastric, umbilical & left hypochondriac region. J shaped (vertical) Obese persion - horizontal Length- 25cms Capacity- 1.5 to 2 Ltr

4. Anatomy of stomach It has 4 parts- Cardia Fundus Body Antrum Pylorus

5. Anatomy of stomach 2 Curvatures Greater curvature Lesser curvature 2 Surfaces Anterosuperior surface Posteroinferior surface

6. Anatomy of stomach RELATIONS OF STOMACH ANTERIOR - Liver Diaphragm Transverse colon Anterior abdominal wall POSTERIOR - Diaphragm Splenic flexure of colon Left kidney Pancrease Splenic artery Left suprarenal gland Transverse mesocolon

7. BLOOD SUPPLY OF STOMACH LESSER CURVATURE LEFT GASTRIC ARTERY (COELIAC TRUNK) RIGHT GASTRIC ARTERY (HEPATIC ARTERY) GREATER CURVATURE LEFT GASTROEPIPLOIC ARTERY (SPLENIC ARTERY) RIGHT GASTROEPIPLOIC ARTERY (GASTRODUODENAL ARTERY) FUNDUS SHORT GASTRIC ARTERY (SPLENIC ARTERY)

8. NERVE SUPPLY OF STOMACH SYMPATHETIC T 6 to T 10 spinal segments Motor to pyloric sphincter Carry pain sensation from stomach PARASYMPATHETIC Vagus nerve & its branches Gasric motility Gastric secretion

9. LYMPHATIC DRAINAGE OF STOMACH A - pancreatico -splenic nodes B - right gastroepiploic nodes C - left gastric nodes D - pyloric nodes All ultimately drains into Coeliac nodes. A B C D

10. PHYSIOLOGY OF STOMACH FUNCTION OF THE STOMACH Storage of food until it is processed Mixing of food with gastric secretion and forms a semisolid micture called Chyme. Slow emptying of chyme from stomach into small intestine at a suitable rate for better digestion and absorption.

11. Gastric glands Gastric glands are located beneath the gastric pits within gastric mucosa. Gastric glands are named according to their location. Cardiac glands - found in cardia of stomach Fundic glands- found in fundus of stomach Pyloric glands- located in antrum & pylorus

12. Gastric cells Mucus cell Parietal cell Chief cell Enterochromafin cell

13. Parietal cell Present only in fundus of stomach Secrete HCL & intrinsic factor INTRINSIC FACTOR- required for absorption of vitamin B 12 HCL- main component of gastric juice Kills micro organism present in food Activate pepsinogen(inactive) to Pepsin(active) required for protein breakdown & digestion.

14. Chief cell Present only in fundus Secrete PEPSINOGEN- inactive form of pepsin, required for protein breakdown & digestion.

15. Composition of gastric juice Approx secretion of gastric juice is 1.5 – 2 ltr per day When meal is consumed, it stimulates release of gastric juice from gastric glands. HCL Pepsin Sodium intrinsic factor potassium gastric lipase bicarbonate Gastric Juice water solutes Inorganic Organic

16. Gastric acid secretion

17. Phases of gastric secretion Cephalic phase Gastric phase Intestinal phase

18. Cephalic phase It occurs even before food enters the stomach It results from sight, smell, thought of food. It accounts for 30% of gastric secretion. Neurogenic signal transmit through vagus nerve (dorsal motor nuclei).

19. Gastric phase Once food enters the stomach, it excites local enteric reflex, gastrin mechanism, which causes stimulation of gasric juice secretion. It accounts for 60% of gastric secretion.

20. Intestinal phase Presence of food in duodenum or upper part of small intestine , stimulate stomach to secrete small amount of gastric juice. This is due to relase of gastrin in duodenal mucosa. It accounts of 10% of gastric secretion.

21. Regulation of gastric acid secretion Stimulated by – acetylcholine, gastrin, histamine. Inhibited by- presence of food in small intestine. presence of acid, fat, protein breakdown product. secretin. gastric inhibitory peptides VIP somatostatin

22. Gi motility & Gi emptying When food enters stomach the fundus and upper part of body relax and accommodate the food. Peristalsis begins in the lower portion of body, mixing and grinding the food and permitting chyme pass through pylorus and enter the duodenum. In regulation of gastric emptying the antrum, pylorus, upper duodenum function as unit. Contraction of antrum is followed by sequential contraction of the pyloric region and duodenum.

23. Regulation of gastric motility & emptying The rate at which the stomach empties into duodenum depends on the type of food ingested. Food rich in carbohydrate empties fast Protein rich food leaves slowly. And fat containing food leaves stomach very slowly. The rate of emptying also depends on osmotic pressure of the chyme. CCK is also an inhibitor of gastric emptying.

24. Peristalsis Peristalsis is the radial symmetrical contraction and relaxation of muscles that propagates in a wave down the tube, in anterograde direction. In stomach the co ordinated contraction of circular & longitudinal muscle result in movement of chyme in forward direction. Presence of food in stomach result in gastric secretion and peristalsis. In order to stop or decrease the peristalsis (during OT), we need to decompress the stomach with ryle’s tube.

25. Pacemaker for gastric peristalsis The source of myogenic activity in GIT has been tracked down to INTERSTITIAL CELLS OF CAJAL, which act as pacemaker, that generates slow wave in smooth muscle.

26. Interstitial cell of cajal These are the type of interstitial cell found in GIT. Myenteric interstitial cell of cajal (ICC MY) serve as a pacemaker bioelectrical slow wave potential that leads to contraction of smooth muscle. These contraction of smooth muscle result in peristalsis.

27. Gastrointestinal hormones

28. achlorhydria Failur of stomach to secrete HCL, despite maximum stimulation. It also prevent the function of pepsin.

29. Gastric atrophy Normally gastric secretion contains Intrinsic factors. In case of atrophy there is reduced intrinsic factors. Results in decrease absorption of vitamin B12 in ileum. This may lead to pernicious anemia.

30. gastritis Inflammation of gastric mucosa. May be associated with H. Pylori Upper abdominal pain, nausea, vomiting, indigestion, heart burn. Diagnosis can be done by endoscopy + biopsy Rx antibiotic, PPI

31. Gastric ulcer Break in the inner lining of stomach.. Due to H. Pylori infection or NSAIDS. Presented with upper abdominal pain and dyspepsia. Dx by upper GI endoscopy + biopsy. Rx antibiotic, PPI

32. motility disorder Gastroesophageal reflux disorder Achalasia cardia

33. GErd It’s a type motility disorder due to malfunction of lower esophageal sphincter. It cause backflow of stomach content & acid into esophagus. That irritate and damage the esophageal lining. Pt may experience nausea, heartburn, regurgitation, bitter taste, dry cough. Diagnosis by Upper GI endoscopy. Complications- esophagitis, esophageal stricture, barrett’s esophagus. Treatment includes – Antacids, PPI

34. Surgical treatment of gerd Fundoplication – wrapping the top of stomach around lower esophageal sphincter, thus prevent reflux. LINX DEVICE - ring of magnetic beads wrapped around the junction of stomach & esophagus. The magnetic attraction between the beads is strong enough to prevent acid reflux, but weak enough to allow food.

35. Achalasia cardia Due to failure of lower esophageal sphincter to relax. Difficulty for food to pass down to stomach People may complain of heart burn, regurgitation, difficulty in swallowing. Diagonsis by barium swallow, esophageal manometry, endoscopy Treatment – esophageal dilatation, myotomy.

36. PHYSIOLOGY OF DUODENUM Quick anatomy of duodenum. Physiology of duodenum function of duodenum Duodenal Glands & Scecretion Disorder of Duodenum

37. Anatomy of duodenum Duodenum is the first portion of small intestine. C shaped. 10-15 inch It has four parts- 1st part / superior part (L1) 2 nd part / descending part( L3) 3 rd part / horizontal part 4 th part / ascending part (L3)

38. Blood supply of duodenum Proximal to 2 nd part- Gastroduodenal A & Superior Pancreaticoduodenal A Distal- superior mesenteric A & Inferior Panceraticoduodenal A

39. Lymphatic drainage of duodenum Anterior - Panceaticodudenal lymphnode , pyloric lymphnode Posterior- superior mesenteric lymphnode ,

40. Physiology of duodenum Duodenum is lined by mucus secreting columnar epithelium. Endocrine cells in duodenum produce CCK & secretin in response to acid and fatty food. These inhibit gastric acid secretion.

41. Function of duodenum Gate controller of food from stomach to jejunum. This is the first site of contact for gastric secretion, bile, digestive enzymes from gall bladder and pancreas. Play important role in digestion and absorption of nutrients.

42. Duodenal glands & Secretion BRUNNER’S GLAND Found only in duodenenal submucosa. It produce mucus (bicarbonate rich) Protect duodenum from acidic content of chyme. Provide alkaline medium for activation of intestinal enzyme Lubricate the intestine.

43. duodenitis Inflammation of duodenal mucosa May be due to H. pylori bacterial infection NSAIDS Autoimmune (Crohn’s disease) Dx by endoscopy + biopsy RX antibiotics, PPI

44. Duodenal ulcer Ulcer due to infection by H.pylori . This bacteria erodes the protective barrier of duodenal mucosa, predisposing it to damage by gastric acids. Pt presented with upper abdominal pain & dyspepsia. Diagnosis by Endoscopy + biopsy Managed by antibiotics, PPI, Antacids.