Salivary glands/Gastric juice/peptic ulcer

Salivary glands are glands in the mouth that produce saliva, or spit. They help with digestion, swallowing, and keeping teeth health

1. Dr. K. Ambareesha PhD,. Associate Professor, Physiology GMC Jangaon SALIVARY GLANDS

2. LEARNING OBJEVTIVES Composition Mechanism of secretion Functions And regulation of saliva

3. Salivary Glands Type Histology % contribution to salivary secretion Parasympathetic nerve supply via 1. Parotid Contains pure serous cells 25% IX nerve 2. Submandibular or submaxillary Serous: mucous cells : : 4:1 70% VII nerve 3 . Sublingual Serous : mucous cells : : 1:4 5% VII nerve

4. Composition of Saliva Daily secretion: 1500 mL /day. Enzymes: Ptyalin (salivary α - amylase) Lysozymes (bactericidal) Lingual lipase Mucin IgA : → local protection against bacteria and viruses. Electrolytes – cations : Na + , K + , Ca 2+ ; Anions: Cl – , HCO 3 – pH: 7.0 (resting states); 8.0 (during active states)

5. Functions of Saliva Ptyalin (salivary α - amylase) digest starch to α - limiting dextrin and maltose (optimal action at pH 6.5) readily inactivated at pH ≤ 4.0. Mucin lubricates the food, facilitates swallowing protects oral mucosa aids speech Serves as a solvent → activate taste buds. Prevents dental caries (contains lysozymes , IgA and lactoferrin- bacteriostatic ). Maintains oral pH at 7.0 → protects tooth enamel.

6. MECHANISM OF SALIVARY SECRETION Primary secretion Modification of saliva

7. Control of Salivary Secretion 1. Acinar cells → primary secretion ( isotonic ); flnal salivary secretion hypotonic . (Rich in K + and HCO 3 – )

8. As salivary flow increases, Na + , Cl – and HCO 3 – concentration ↑ s, K + concentration ↓ s → isotonic final salivary secretion. Stimulation of parasympathetic nerves → profuse watery saliva (Atropine ↓ s salivary secretion). Stimulation of sympathetic nerve → secretion of small amounts of saliva rich in organic constituents and mucus. Increases by: taste of food ( inborn reflex ) by sight, smell or thought of food ( psychic or conditioned reflex ) dry food

9. Aptyalism ( xerostomia ) Causes: anxiety, fear, fever, duct obstruction Sialorrhoea Causes: pregnancy, tumour , VII CN damage Aldosterone : ↑ [K + ] and ↓ [Na + ] of saliva. In Addison’s disease → high salivary Na + /K + ratio.

10. Mumps: viral infection of parotid Xerostoomia : reduced salivary secretion resulting in dryness of mouth Applied:

11. Regulation of salivary secretion by the parasympathetic nervous system .

12. GASTRIC JUICE SECRETION

13. GASTRIC JUICE Composition Mechanism of secretion Functions Regulation of gastric juice secretion Gastric function tests

14. Composition and Functions of Gastric Juice

15. Composition and Functions of Gastric Juice

16. Mechanism of Secretion Gastric glands are made up of six types of cells Type of cell …………………………..>Secretion 1. Parietal or oxyntic cell ……> HCl , Intrinsic factor 2. Chief cells …………………..> Pepsinogen 3. Mucous cell…………………..> Mucus 4. Enterochromaffin Like Cell (ECL cell>Histamine 5. “D” cells …………………> Somatostatin 6. “G” cells ………………….> Gastrin

17. Mechanism of HCl secretion in the parietal cells of the stomach.

18. Mechanism Of HCl secretion:

19. Regulation of HCl secretion

20. Regulation of HCl secretion Agents → Regulation of HCl secretion by the parietal cell and their mode of action ↓ by: PGE 2 ↑ by: histamine, A- ch , gastrin ; (M 3 : M 3 muscarinic receptor; G R : gastrin receptor; AC : adenylate cyclase ; ECL : Enterochromaffin like cells; G s and G i protien : ‘s’ and ‘ i ’ denotes stimulatory and inhibitory actions respectively)

21. Factors affecting HCl secretion

22. R egulation of Secretion of Gastric Juice 1. Nervous regulation: Vagus is secretomotor nerve to stomach → ( vagal juice). Mechanism ( i ) release of GRP → ↑ gastrin secretion → ↑ acid secretion. (ii) release of A- ch → ↑ acid and pepsinogen secretion. 2. Humoral regulation: Psychic stimuli, food in stomach → (+) vagus nerve → release of gastrin → ↑ gastric juice secretion.

23. Phases of gastric juice secretion Cephalic Phase Gastric Phase Intestinal Phase 1. Cause: Psychic stimulation (called appetite juice ). 1. Stretching of the receptors in stomach wall ( mechanical stimulus ), and products of digestion ( chemical stimulus ). 1. It occurs when food enters the duodenum. 2. Mediated by: Vagus. 2. ‘Local reflex’ responses and ‘gastrin’. 2. ‘Reflex’ and ‘hormonal feedback’ effects from small intestine. 3. Contribution to the total secretion: 30–50%. 3. 50- 60%. 3. Much less.

24. Gastric secretion occurs in four phases: a) Cephalic phase b) Gastric phase c) Intestinal phase d) Interdigestive phase

25. a) Cephalic phase

26. Inhibition of Gastric secretion Presence of food in the intestine inhibit it, inhibitory influences are both neural and chemica Neural inhibition : is by enterogastric reflex; strech of intestine by chyme and products of protein digestion. The presence of acid, fat, products of protein breakdown in the upper part of small intestine helps in the secretio n of secretin , GIP, VIP and somatostatin which inhibits gastric secretion

27. Experimental Evidences- Sham feeding Sham feeding experiment to demonstrateinitiation of cephalic phase of gastric secretion.

28. Heidenhain’s pouch

29. Gastric function tests Fractional test meal Histamine test Augumented histamine test Pentogastrin test Insulin test Barium meal Blood and urine pepsinogen IF secretion Applied: Total Gastrectomy Deficiency of I.F. → pernicious anaemia . Protein digestion normal. Iron deficiency anaemia Rapid absorption of glucose → hyperglycemia → abrupt rise in insulin secretion → hypoglycemia. Dumping Syndrome: Weakness, dizziness and sweating after meals:

30. Peptic Ulcer Definition: Pathogenesis Mucosal-bicarbonate barrier disruption with bacteria Helicobacter pylori inf. or ↑ acid secretion. Hypersecretion of gastric acid → ulcers of duodenum and pre- pyloric portion of the stomach. ↑ sensitivity to gastrin .

31. Increased pepsinogen I levels →↑ gastric acid secretion → 5 fold increase in incidence of peptic ulce

32. Sequence of events of pathophysiology of peptic ulcer by H. pylori.

33. ZOLLINGER-ELLISON SYNDROME is characterized by secretion of excess hydrochloric acid in the stomach. Caused by Tumor of pancreas which produces gastrin in large amount Gastrin increases the hydrochloric acid secretion in stomach by stimulating the parietal cells of gastric glands .

34. THANK YOU