Digestive system IIHistology

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Digestive system II:

Digestive system II Dr Pankaj Maheria

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Digestion is the process by which food is enzymatically broken down into molecules that are small enough to be absorbed into circulation. Consist of oral cavity and a hallow tubular gastrointestinal tract plus digestive gland associated with it Main function Digestion of food Absorb the nutrients

Gastrointestinal tract :

Gastrointestinal tract A muscular tube line by mucous membrane that exhibits regional variations reflecting the changing functions of system from mouth to anus. Break down of food for absorption Five main process Ingestion Fragmentation Digestion Absorption Elimination of waste products Gut associated lymphoid system

Part of gastrointestinal tract:

Part of gastrointestinal tract

General structure of GIT:

General structure of GIT Four distinct coat From inner to outer side Mucosa Submucosa Muscularis externa Adventitia

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Mucosa: three layers Epithelium Lamian propria Connective tissue Glands GALT

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Mucosa: three layers Muscularis mucosa Smooth muscle Two layers: Inner: circular Outer: longitudinal Keeps the mucosal surface and gland in constant state of general agitation which expels secretion from deep glandular crypts , prevent clogging and enhance contact between epithelium and luminal contents for absorption.

Sub-mucosa:

Sub-mucosa Fibro-elastic tissue Adipose tissue Highly vascular May contain gland ( esophagus and duodenum) Meissner’s nerve plexus

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Muscularis externa Two layers of smooth muscle Inner circular Outer longitudinal Peristaltic contraction Esophagus skeletal muscle Contains Auerbach’s plexus ( myentric ) and parasympathetic ganglia

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Adventitia/ Serosa Adventitia: loose connective tissue without peritoneum Serosa : peritoneum over a layer of connective tissue.

Oesophagus :

Oesophagus

Mucosa:

Mucosa Epithelium: Stratified squamous non keratinized. Lamina propria : More collagenous Oesophageal gland in lower part.

Mucosa:

Mucosa Muscularis mucosa More prominat Single layer of longitudinal layer of smooth muscle.

Submucosa :

Submucosa Loose with many elastic fibres . Oesophageal gland seromucous

Muscularis externa :

Muscularis externa Upper one third Only skeletal muscle Middle one third Both skeletal and smooth muscle Lower one third: Only smooth muscle

Adventitia :

Adventitia Same as general plan of GIT .

stomach:

stomach

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Muscular bag that receive food bolus from oesophagus . Acidify and convert the ingested food into a thick viscous pulp called chyme . Absorbs water , salt , alcohol and certain drugs. Mucosa show longitudinal rugae with disappear when stomach is full. Gastric pit or foveolae gastricae . All gland open in bottom of gastric pits. Histological divide in three part Cardia Fundus or body Pylorus

Mucosa :

Mucosa Epithelium Simple tall columnar epithelium Secretes mucus that lubricates and protects the epithelium from acid contains. Gastric pit. Renewed every three day.

Mucosa :

Mucosa Lamina propria Gastric gland Muscularis mucosa Two layers Muscle fibres extend into lamina propria between glands .

Submucosa :

Submucosa Same as general plane

Muscularis externa:

Muscularis externa Three layers Inner oblique Middle circular Outer longitudinal

Serosa:

Serosa Same as general plan

Salient features of each region of stomach:

Salient features of each region of stomach

Cardia :

Cardia Change in epithelium Stratified squamous to simple columnar. Cardiac gland in lamina propria Presence of shallow gastric pit.

Fundus and body:

Fundus and body Shallow gastric pit lined by simple columnar epithelium. Pit form one fourth of thickness of mucosa. Lamina propria: Simple branched tubular fundic gland.

Cell in fundic gland:

Cell in fundic gland Mucous neck cells Parietal or Oxyntic cells Chief or Zymogenic cells Enteroendocrine cells

Mucous neck cells:

Mucous neck cells Low columanr in neck region of gland. Secreting acid mucus.

Parietal or Oxyntic cells :

Parietal or Oxyntic cells Large pyramidal cells found in upper part of gland. Acidophilic cytoplasm Attached to periphery of gland. Secrete : Hydrochloric acid Gastric intrinsic factor

Parietal or Oxyntic cells :

Parietal or Oxyntic cells Copious eosinophilic cytoplasm and central nucleus Fried egg appearance

Chief, Peptic or Zymogenic cells:

Chief, Peptic or Zymogenic cells Small cuboidal cells Bordering the glandular lumen Deeper part of gland. Basophilic cytoplasm. Condensed basally located nuclei. Secrete Pepsinogen Lipase Amylase

Enteroendocrine cells:

Enteroendocrine cells Unicellular endocrine cells Basal part of gland Special stain Secretory granules in basal part of cytoplasm. Secrete Enteroglucogon Amines

Pylorus :

Pylorus Deep gastric pit Pits form one half thickness of mucosa. Pyloric gland in lamina propria. G cells Middle circular layer thicken to for pyloric sphincter.

Stomach :

Stomach Fundic stomach Pyolric stomach

PowerPoint Presentation:

Gastric ulcer Pernicious anemia

Thank you………:

Thank you………

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