GIT Lecture PDF

1. Salivary glands 2. Pancreas 3. Liver 4. Gall bladder - **Oral cavity** - **Oropharynx** - **Oesophagus** - **Stomach** - **Small Intestine** - **Large intestine** - **Rectum & Anal canal** ### [Structure of the wall of the digestive tract:] 4 laye...

1. Salivary glands 2. Pancreas 3. Liver 4. Gall bladder - **Oral cavity** - **Oropharynx** - **Oesophagus** - **Stomach** - **Small Intestine** - **Large intestine** - **Rectum & Anal canal** ### [Structure of the wall of the digestive tract:] 4 layers: 1. **[Mucosa]** Epithelium Lamina propria Muscularis mucosa 2. ### [ Submucosa:] CT 3. [ **Musculosa:**] ### [ Serosa:] A. **Epithelial lining:** 1. ### [ Mucosa] ### B. **Lamina propria:** Loose connective tissue C. **Muscularis mucosa:** Two thin layers of smooth muscle cells: Inner circular & outer longitudinal ### [Su​bmucosa:] - **Loose C.T** contains mucous glands in duodenum and oesophagus. ### [ Musculosa:] - 2 layers **Inner circular & Outer longitudinal.** Forms wall proper of the tract. Responsible for the peristaltic movement to propels the content of the gut to the anus. ### Serosa \\Adventitia: - **loose C.T** ± **Mesothelium** 2. [ **Mucosa:**] 3. [ **Submucosa:**] #### esophageal glands 4. [ **Musculosa:**] Stomach ======= Stomach ------- 1. [ **Cardiac region:** ]Surrounds the oesophageal orifice 2. [ **Fundus and body:**] The main part 3. [ **Pylorus:**] The termination A. [ **Mucosa:**] 1. #### Epithelium: - Simple columnar cells - Secrete neutral mucous to protect surface of the stomach from the 2. **Lamina propria:** LCT with glands 3. #### Muscularis mucosa: B. [ **Submucosa:**] LCT C. [ **Musculosa:**] 3 layers: Inner oblique Middle circular Outer longitudinal D. [ **Serosa:**] LCT covered by ### [Fundic glands: ] #### 1- Mucous neck cells: 2. **Parital or oxyntic cells:** Acidophilic cells do not reach lumen Secrete HCL 3. #### [P]eptic (chief) cells: #### Enteroendocrine (Argentaffin cells): 5. **Stem cells.** ### [Pyloric region:] ### [Pyloric glands contain only:] A. Mucous cells B. Enteroendocrine cells C. Stem cells ### [Musculosa:] - 2 layers (Inner circular & outer Longitudinal. - The inner circular layer prominent ### [Function of Small intestine:] 1. Complete digestion of food 2.Absorption ### [It is composed of:] 1. Duodenum 2. Jejunum 3. Ileum ### [General structure of the small intestine:] A. [ **Mucosa:**] #### 1- Epithelium: 2. **Lamina propria:** Loose CT 3. #### Muscularis mucosa: B. [ **Submucosa:**] LCT C. [ **Musculosa:**] D. [ **Serosa:**] LCT ± mesothelium ### [Intestinal villi] ### Intestinal epithelium: A. [ **Epithelial cells covering the vil**]**li:** 1. Simple columnar absorptive cells **( Enterocytes)** 2. **Goblet cells:** 3. **Enteroendocrine cells:** B. #### Epithelial cells lining the crypts : 4. **Enterocytes** **Jejunum shorter Tonguelike** **Ileum Long,slender Fingerlike Absentover peyer\'spatches** -- -- -------------------------------- -------------------------------------------------------------- **Numerous** **Numerous** **Neitherglands norpeyer\'s** **Peyer\'spatches** - **Brunner\'s gland:** Mucous glands open into the base or sides of the crypt. They secrete alkaline mucous which protect the duodenal mucosa from the acid chyme. - **Peyer\' s patches: Lymphoid aggregations.** The large intestine =================== - **Cecum** - **Ascending colon** - **Transverse colon** - **Descending colon** - **Sigmoid (pelvic colon)** ### Structure of large intestine 1. [ **Mucosa:**] Differs from that in small intestine in: - [ **Lamina propria:**] - **Crypts are lined with:** 4. **Stem** cells - [ **Muscularis mucosa**] inner circular and outer longitudinal 2. **[Submucosa:]** LCT rich in lymphatic nodules 3. **[Musculosa:]** - Continuous inner circular - Outer longitudinal muscle fibers arranged into 3 bundles called #### taeniae coli. 4. **[Serosa:]** +-------------+-------------+-------------+-------------+-------------+ | **Esophagus |  | | | | | | **St.Sq. | | | | | | non- Kerat. | | | | | | Epith.** | | | | +-------------+-------------+-------------+-------------+-------------+ | | **Fundic | | | | | | glands** | | | | +-------------+-------------+-------------+-------------+-------------+ | | **Pyloric | | | | | | glands** | | | | +-------------+-------------+-------------+-------------+-------------+ | **Duodenum* | **Leaf | | | | | * | shaped | | | | | | villi, Few | | | | | | goblet | | | | | | cells** | | | | +-------------+-------------+-------------+-------------+-------------+ | | **Tongue | | | | | | shaped** | | | | | | | | | | | | **villi, | | | | | | Moderate | | | | | | goblet | | | | | | cells** | | | | +-------------+-------------+-------------+-------------+-------------+ | | **Finger | **Payer\'sp | | | | | like villi | atches** | | | | | with, many | | | | | | Goblet | | | | | | cells** | | | | +-------------+-------------+-------------+-------------+-------------+ | **Largeinte | **Crypts | | | | | stine** | only full | | | | | | Of goblet | | | | | | cells** | | | | +-------------+-------------+-------------+-------------+-------------+  1. **Salivary glands** 2. **Pancreas** 3. **Liver** 4. **Gall Bladder** Salivary glands --------------- Types of salivary glands ======================== 1. **Parotid.** 2. **Submandibular** 3. **Sublingual glands.** Pancreas -------- **Stroma** **Acini** **Parenchyma** Pancreatic Parenchyma --------------------- - basal Nuclei - Basal basophilia - Apical acidophilia - Basal striations - centroacinose cells 1. **Beta cells: 70%** 2. **Alpha cells: 25%** 3. **Delta cells: 3%** 4. **Pancreatic polyeptide cells: 1-2 % Unknown function.** ### Liver ### [Blood supply:] 1. 75% comes from the portal vein (02 poor & nutrient rich), 2. 25% by hepatic artery (02 rich). 1. **Cells (hepatocytes)** 2. **Hepatic artery carrying O2** 3. **Portal vein carrying blood from GIT** 4. **Bile ducts to secrete bile** A.  [ **Portal tract contains:**] 1. A branch of the portal vein: widest, with thin wall. 2. A branch of hepatic artery: rounded, with narrow lumen. 3. A branch of the bile duct: lined with cubical epithelium. 4. Lymph vessel.  ### [ Hepatocytes] ### [EM of hepatocyte:] A. #### The cell membrane: 1. **Facing the blood sinusoids:** long microvilli 2. **Facing the bile canaliculus:** short microvilli. B. **The Cytoplasm:** Hepatocytes are very active cells So they are very rich in organelles & inclusions: 3. **Mitochondria:** very numerous (1000-2000/cell) 4. [ **rER & ribosomes**]**:** abundant to synthesize proteins 5. **sER:** (metabolism + drug & poison detoxification). 6. **Golgi Apparatus:** well developed, concerned with secretion (plasma proteins), turnover of the cell membrane & formation of Iysosomes. 7. **Lysosomes:** also numerous to destroy worn out cellular components, and to digest & eliminate waste products. 8. **[Microbodies (peroxisomes):]** very numerous, concerned with metabolism of H202, lipid degradation into glucose & alcohol metabolism. 1. fenestrated endothelial cells that are surrounded by 2. a special type of macrophages (von Kupffer) cells. ### [Von Kupffer Cells: macrophage of liver] ### [Their main functions:] ### [The Space of Disse (Perisinusoidal Space):] 1. [ Long microvilli] projecting from the surface of hepatocytes 2. [ Reticular fibers] that support the wall of the sinusoids. 3. [Blood plasma] containing all the nutrients 4.  [Lipocytes (Ito cells);] branching lipid storing cell that store the fat soluble vitamin A in the form of retinyl ester in lipid droplets.