SHSU BIOL 3490 - Digestive System: Alimentary Canal

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Digestive System: Alimentary CanalAlimentary Canal- Tube from mouth to anusComponents- Esophaguso Muscular tube- Stomacho Storage tank- Small Intestineo Nutrient Absorptiono Chemical Digestion- Large Intestineo Absorption of water and elimination of solid waste- AppendixAlimentary Canal: Four Tunics- Mucosa- Submucosa - Muscularis Externa- Serosa Mucosa (Inner Layer – always next to lumen)- Lines lumen from mouth to anus- Secretes mucus, enzymes, hormones- Absorb digestive products - Protects against diseaseTunics: HistologyMucosa- Epitheliumo Simple columnar - Lamina Propriao Areolar C.To Capillarieso Lymphatics- Muscularis Mucosaeo Smooth muscleSubmucosa- Dense Irregular C.T with Elastic Fibers- Blood and lymph vessels- Meissner’s Submucosal Plexuso Controls motility of mucosaMuscularis Externa- Smooth muscleo Inner circular o Outer longitudinal Serosa- Areolar C.T- Simple SquamousEnteric Nervous System- Self-contained nervous systemEsophagus: HistologyMucosa - Stratified squamous to simple columnar - Langerhans cellso Phagocytes Lamina Propria- Areolar C.TMuscularis Mucosa- One sheet of smooth muscleo Longitudinal Submucosa- Dense Irregular C.TMuscularis Externa- Part skeletal + Smooth MuscleStomach: HistologyMucosa- Simple columnar o Fundus Cells + Glandular Cells- Fundus Cellso Mucous neck cellso Stem cellso Parietal cells Produce HCIo Chief Cells Produce protein enzymes- Cardiac Regiono Gastric pits shallower- Pyloric Regiono Gastric pits deepLamina Propria- Areolar C.TMuscularis Mucosa- Smooth Muscle (3 Layers)o Inner circular o Outer longitudinalSubmucosa- Dense Irregular C.TMuscularis Externa- Smooth Muscle (3 Layers)o Inner obliqueo Middle circularo Outer longitudinalSerosa- Areolar C.T- Simple SquamousStomach: Four Regions - Cardiac o Entry of food- Fundus- Body- Pyloric Regiono Pyloric sphincter controls stomach emptyingStomach: Components- Mucosal Barriero Prevents stomach from digesting itselfo Epithelial cells with tight junctionsSmall Intestine: HistologyMucosa- Simple Columnar- Apical surface = brush border o Surface of an epithelial cell that faces lumen- Cells are absorptive- Cellso Goblet Cells o DNES Cells Produce hormoneso Microfold Cells Phagocytes that transport antigens to lamina propriaLamina Propria- Areolar C.T- Crypts of Lieberkühno Glands that lie between villi- Paneth Cellso Produce lysosomes Muscularis Mucosae- Smooth Muscleo Inner circularo Outer longitudinalSubmucosa- Dense Irregular C.T- Meissner’s submucosal plexus- Peyer’s Patcho Google: Lymphoid follicles that plays a role in the immune systemMuscularis Externa- Smooth muscleSerosa- Areolar C.T- Simple Squamous*In the submucosa of duodenum, there are Brunner’s gland (Mucous glands). Small Intestine: Three regions- Duodenum- Jejunum- IleumSmall Intestine: Components + Notes- Lactealo Lymph vessel type o Absorption of lipids- Digestive process depends on delivery of chyme (digestive secretions)- True peristalsis after most nutrients is absorbed. Large Intestine: Four Subdivisions- Cecum- Vermiform Appendixo Masses of lymphoid tissue- Colon- Rectumo Have rectal valves that separate feces from flatusColon + Rectum + Appendix: Histology- No Villi- Crypts of Lieberkühn o Google: Provide stem cells for renewal of the intestinal epithelium- In rectum, crypts are deeper and fewer- In appendix, there is added lymphatic tissueAnal Canal: HistologyMucosa- Simple cuboidal changes to stratified squamousSubmucosa- Fibroelastic C.TMuscularis Externa- Inner and outer smooth muscle- Smooth muscle is replaced by skeletal muscleLarge Intestine: Notes- Muscularis is reduced, except at the endo Teniae coli = 3 Bands of Smooth Muscle Forms Haustra (Sac Areas)oDefinitions:- Ganglia: Cluster of neural bodies- Rugae: Longitudinal folds- Villi: Finger-like projections of mucosao Absorptive columnar cells- Microvilli: Tiny projections of the plasma membrane - Apical surface: Surface of an epithelial cell that faces lumen- Urogastrone: Human epidermal growth factoro In duodenum- Meissner’s Submucosal Plexus: Controls motility of mucosa- Rectal Valves: Internal transverse folds- Haustra: Sack-like

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SHSU BIOL 3490 - Digestive System: Alimentary Canal

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