1. Introduction and Physiological anatomy of Gastro Intestinal tract Every cell of living system needs energy Unicellular organisms: Exists in the sea of nutrients Can satisfy their nutritional need just by Proteins present at the cell membrane

2. Multi cellular organisms In multi cellular organisms, a groups of cells converted to a tissue, to perform specific function A number of systems are evolved in vertebrates including humans To provide nutrients to all the systems The Gastro intestinal tract is accounted for extraction of nutrients from the food

3. The Food The most of the food we eat are macromolecules, it can not cross the cell membrane easily so it must be converted to monomers Gastrointestinal tract is to make the food in absorbable form by help of chewing and mixing with various enzymes in mouth to small intestine

4. Digestive system

5. Components of GIT Various partsGlands includes Oral Cavity Salivary glands Oesophagus Gastric glands Stomach Pancreas Duodenum Jejunum Liver and biliary system Ileum Intestinal glands Jejunum Endocrine glands Cecum Enteric nervous system Colon Circular smooth muscles Rectum and anal canal Longitudinal muscles

6. Structure of wall of the GIT

8. Structure of intestinal villi

9. Salivary functions and its regulation Saliva is the mixed glandular secretion which constantly bathes the teeth and the oral mucosa First secretion encounter the food It is vital for oral health It is constituted by the secretions of the three paired major salivary glands; Parotid, sub mandibular and sublingual It also contains the secretions of the minor salivary glands

10. Structure of salivary Glands

11. Parotid gland Parotid Is large accounts for 50% sec. of saliva (when stimulated) Situated in front of ear behind the ramus of mandible Gland drain in to oral cavity opposite to second molar tooth Secretions are basically serous

12. Structure of sub mandibular and sub lingual gland

13. Submandibular and sub lingual gland The submandibular gland is variable in size being about half the size of the parotid lies above the mylohyoid in the floor of the mouth. It opens into the floor of the mouth underneath the anterior part of the tongue The sublingual is the smallest of the paired major salivary glands, It is situated in the floor of the mouth beneath the sublingual folds of mucous membrane.

14. Structure of salivary gland

15. Composition of saliva Water 99.55% solid 0.45% pH 7.04 Na, K, Ca, Mg, Cl, HCO3- and phosphate Organic substances includes IgA, Lysozymes, albumin, glucose, lactate, urea and ammonia etc. Normal salivary flow rates are 0.3-0.4 ml/min when unstimulated and 1-1.5 litre/day when stimulated Approximately 0.5 – 0.6 litres of saliva is secreted perday

16. Functions of saliva Initiate the digestion of starch Protects oral cavity (IgA and lysozymes) Provide lubrication for food to make bolus Facilitate the taste When salivary flow is reduced, dryness of the mouth occurs and information from osmoreceptors are translated to increase the water intake Helps in speaking, swallowing, chewing Buffer the gastric secretions reflux in to the oesophagus

18. Control of salivary secretion Basically controlled by parasympathetic, sympathetic stimulation causes proteinaceous secretion without affecting the volume

19. Xerostomia (salivary flow< 0.2 ml/min) The presence of saliva is vital to the maintenance of healthy hard (teeth) and soft (mucosa) oral tissues. Severe reduction of salivary output results in a rapid deterioration in oral health Patients suffering from dry mouth can experience difficulty with eating, swallowing, speech, the wearing of dentures, trauma to and ulceration of the oral mucosa, taste alteration, poor oral hygiene, a burning sensation of the mucosa, oral infections including Candida and rapidly progressing dental caries After radio therapy, old age and multidrug therapy