L1-Esophagus & Stomach Team 443.pdf

Esophagus & Stomach Color index: -Main text -important -female slides -male slides -Dr.note -Extra Editing File [ Gastrointestinal & Nutrition Block | Histology ] Objectives At the end of this lecture, you should be able to answer the following (objectives): ● Describe the microscopic structure...

Esophagus & Stomach Color index: -Main text -important -female slides -male slides -Dr.note -Extra Editing File [ Gastrointestinal & Nutrition Block | Histology ] Objectives At the end of this lecture, you should be able to answer the following (objectives): ● Describe the microscopic structure in correlation with the function of: 1. Esophagus. 2. Stomach. Table of contents: Alimentary canal Stomach glands cell types Fundus vs pylorus Esophagus Stomach This lecture was presented by: Prof. Aly Mohamed Prof. Raeesa Abdultawab Alimentary Canal Is the tubular portion of digestive system Subdivided into: Esophagus,Stomach,Small intestine,large intestine. small intestine (duodenum,jejunum and ileum) large intestine (cecum, colon, rectum, anal canal, and appendix). General Architecture of L/M Structure of Alimentary Canal : Mucosa Or Serosa Submucosa Adventitia/Serosa Muscularis externa Esophagus Four concentric Layers: Majority of the esophagus is in the thoracic Esophagus Mucosa Is irregular to change the diameter for squeezing and conducting the food ● Epithelial Lining: Non-Keratinized Stratified Squamous Epithelium. ● Lamina propria: Loose areolar C.T. with mucosal esophageal glands (secretion of mucus) for lubrication found in the upper and lower ends. with little or no in the mid & lymphoid aggregations (nodules) ● Muscularis mucosae: Few layers of smooth muscle fibers. Loose areolar C.T. with blood vessels, nerves, submucosal esophageal glands (secretion of mucus) and Meissner’s plexus of nerve fibers and nerve cells. Submucosa 1- Two muscle layers : Inner circular & Outer longitudinal layers ●Upper 1⁄3 : Both are skeletal muscles(‫) ﻋﺷﺎن ﻛذا ﺗﻘدر ﺗرﺟّ ﻊ‬ (Near the oral cavity = skeletal muscle but involuntary) Muscularis Externa ●Middle 1⁄3 : Inner is smooth muscle & Outer is skeletal muscle ●Lower 1⁄3 : Both are smooth muscles (Near the stomach = smooth muscle) 2- Auerbach’s (myenteric) plexus in between two layers. Serosa/Adventitia ● Adventitia: Loose areolar C.T. not covered by mesothelium in the Cervical & Thoracic parts ● Serosa: Loose areolar C.T. covered by mesothelium (simple squamous epithelium) in the abdominal part of the esophagus (Mesothelium present at 3Ps: Pleura & Pericardium & Peritoneum) Stomach ● It has 4 regions : 1-cardia 2-fundus 3-body 4-Pylorus. ● Mucosa has folds known as rugae that disappear in the distended stomach. to ( Layers the surface area to capacity ). Fundus(and body) of stomach Pylorus of stomach Surface epithelium: simple columnar mucus-secreting cells. Mucosa Submucosa Muscularis Externa Serosa Composed of: 1. Surface columnar epithelium : simple columnar epithelium secretes mucus. 2. Lamina propria : (C.T) Invaded by numerous Fundic glands & lymphoid elements. 3. Muscularis mucosae: 2 layers of smooth muscle fibers. ● Invaded by pyloric glands. (It secretes mucus which coats and protect stomach) ● Connective tissue containing blood vessels & nerves & Meissner’s (submucosal) plexus. ● No glands. ● Three smooth muscle layers: Inner oblique , Middle circular , Outer longitudinal. ● Two smooth muscle layers : Inner circular , outer longitudinal. ● Auerbach’s (myenteric) plexus. ● Auerbach’s (myenteric) plexus. C.T. covered by mesothelium Stomach (Fundus vs Pylorus) Content Fundus Pylorus Mucosa of Fundus of Stomach: Mucosa 1.Lumen. 2.Surface epithelium. 3.pits of pyloric glands. 4.Lamina propria. 5.Muscularis mucosae. 1.Lumen 2.Surface columnar epithelium. 3.pits of fundic glands. 4.Fundic glands. 5.Lamina propria. 6.Muscularis mucosae. 6.Submucosa. (another layer, it isn’t a component within mucosa layer). 7.Muscularis externa. (another layer, it isn’t a component within mucosa layer). Fundic glands have : Glands ● Their Pits are deep : about half of the length of mucosa. ● Short pits : one fourth of mucosa. ● They are branched and convoluted many cross sections. ● Simple branched tubular glands. (It’s function is neutralizing the acidity before reaching the small intestine by secreting mucus) ● Are rich in parietal & chief cells. Female Dr : for MCQ know the difference between - Cells of mucosa of fundus —> contain surface columnar epithelium Stomach Glands cell types Cell type Peptic (chief) cells Parietal (oxyntic) cells -Oxy=acidic -Parietal =due to part of it not sharing the lumen. Mucous neck cells Fundic glands ● ● ● ● ● Pyloric glands The predominant cell type . Nucleus: basal , round. Shape: columnar cells. Cytoplasm: basophilic with apical secretory granules. Secrete: pepsinogen. (inactive form of pepsin) No peptic cells ● Shape: pyramidal or polygonal. ● Nucleus: central , round. ● Cytoplasm: 1-Deeply acidic, rich in SER and mitochondria. (40% of cell volume ). (due to its need for energy). 2- C-shaped intracellular canaliculus. To increase surface area. ● Secrete: 1-HCL 2-Gastric intrinsic factor that helps in absorption Of vitamin B12. Few (or no) parietal cells The predominant cell secrete mucus Secrete mucus Entero = GIT , endocrine= to the blood . Enteroendocrine (EE, DNES) cells. - Cell of fundic glands —> do not contain surface columnar epithelium ● Enterochromaffin (EC) cells (subclass of EE cells): Secretes hormones (serotonin , endorphin) ● ● ● ● EC cells . G cells (secrete gastrin). D cells (secrete somatostatin). A cells (secrete glucagon). DNES =Diffuse neuroendocrine system. Stem cells Regenerative cells (renew the other cell types) MCQs 01 Which of the following cells are not found in the pyloric glands? A- Mucous neck cells 02 B- Stem cells Which one of the following epithelium lines the stomach? ABNon-keratini Keratinized zed stratified stratified squamous squamous 03 D-pseudostratified columnar B- Parietal cells C-Salivary glands D-Inferior of duodenum Which one of the following is lined with stratified squamous epithelium? A- Colon 05 C-Simple columnar Which of the following cells secretes pepsinogen? A- Chief cells 04 B- A cells D-Parietal (oxyntic) cells BDuodenum C-Esophagus D-Stomach The predominant of pyloric glands are : A- Oxyntic cells C-Enteroend B- Chief cells ocrine Answer key: D, C, A, C, D D-Mucous neck cells This Lecture is done by: Members ● ● ● ● ● ● ● ● ● Hamad Alyahya Khalid AlRasheed Faisal Alzuhairy Abdullah Aldhuwaihy Fahad Almughaiseeb Abdulrahman Alosleb Abdulrahman Alomar Omar Banjar Yousof Badoghaish ● ● ● ● ● ● ● Waad Alanazi Raghad Almuslih Reema Alzughaibi Retal Alshohail Raghad Alothman Jouri Almaymoni Shaden Alhazzani Leaders ● Khalid Alanezi ● Waad alqahtani Reviewed by ● Academic leaders