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Digestive System Cells Digestive System Differentiated cells dependent upon location within the system Oral Cavity Esophagus Stomach Small Intestine Large Intestine Accessory Organs/Glands Liver Gall Bladder Pancreas Oral Cavity Oral Mucosa Lines the entire Oral Cavity Stratified Squamous Cells (some areas keratinized) Protection Palate Hard Palate Anterior, superior portion of oral cavity Partially keratinized epithelium; osteocytes Protection Soft Palate Posterior, superior portion of oral cavity Non-keratinized epithelium, layer of skeletal muscle cells, glandular cells Separation from nasal cavity, muscle cells provide lifting action, glandular tissue provides saliva Oral Cavity Oral Mucosa Palate Oral Cavity Tongue Located in the floor of the oral cavity Striated muscle fibers (cells) Myelinated nerve fibers Sensation Filiform Papillae contain keratin at the tip Movement Provides a roughness to the surface of the tongue for controlling food Fungiform Papillae contains taste buds (Clusters of elongated cells around a sensory cell) Taste sensation sent from the tongue to the brain Tongue Striated muscle fibers Oral Cavity Tonsils In mucosa of tongue, palate, & pharynx Made of lymphocytes; stratified squamous in the tongue and palate; pseudostratified columnar in the pharynx Esophagus Cells Cells found lining the esophagus from the oral cavity to the stomach Non-keratinized stratified squamous epithelium Protection Mucus secreting cells Provide lubrication for ease of moving food Muscle fibers Striated muscle (upper 1/3) Movement of food by swallowing Non-striated muscle (lower 2/3) Movement of food by peristalsis Esophagus Cells Stomach Cell Types Surface Mucus Cells Inner surface of the stomach Unlike other mucus cells, their nuclei are not compressed Secrete mucus that is not digested by the stomach acid or enzymes Stomach Cell Types Mucus Neck Cells Located in the upper neck region of the fundus Typical epithelial mucus cell with compressed nucleus and cytoplasm filled with mucus Function unknown Stomach Cell Types Enteroendocrine cells Typically located in the neck, deep in the gastric glands, and in the intestinal crypts Columnar epithelial cells scattered among the absorptive cells and exocrine cells of the GI tract Secrete a hormone that influences gastrointestinal secretions or motility Stomach Cell Types Gastric Chief Cells Located deep in the fundus toward the muscular mucosa Typical appearance of a serous-secretory epithelial cells Secrete digestive enzymes (Pepsin) C: Chief Cells; P: Parietal Cells Stomach Cell Types Gastric Parietal Cells Found most commonly in the middle region of the fundis Large cells with 1-2 oval shaped nuclei; packed full of mitochondria; have deep invaginations called intracellular canaliculus that are covered with microvilli Secrete acid by pumping hydrogen ions across the cell membrane Stomach Cell Types Stem Cells Located in the stomach at the glands as they open into the pits; also in the intestinal mucosa to replace the goblet and absorptive cells Undifferentiated epithelial cells Retain the ability to divide and replace cells which die Intestinal Cell Types Absorptive Cells (Enterocytes) Located in the small intestine and colon Epithelial cells with microvilli (brush border) Microvilli increase the surface area to increase the absorptive capabilities of each cell Goblet Cells Scattered among the absorptive cells in the small intestine and colon Shaped like a “goblet”: narrow at the base and wide at the top Produce mucus to aid in the movement of material through the bowel Intestinal Cell Types Brunner’s Glands (mucus cell) Located in the duodenum Specialized epithelial cell Produce and secrete mucus Paneth Cells Located at the end of the intestinal crypts Typical serous-secretory appearance with the vacuoles containing lysosomal enzymes Secrete anti-bacterial proteins to protect the stem cells in the area Liver Cell Types Hepatocytes Throughout the liver Cuboidal cells with 1-2 nuclei, an abundance of organelles; cells connect into cords with the space of Disse between the cords Functions: Form & secrete bile Store glycogen Synthesize urea Metabolize cholesterol & fat Synthesize plasma proteins Detoxify many drugs Process steroid hormones and vitamin D Liver Cell Types Fenestrated Endothelial Cells Lining the sinusoids of the liver Simple squamous cells with “holes” between the cells and no basement membrane In the liver these cells permit blood plasma to wash over the hepatocytes; secrete substances that control blood flow and coagulation; also assist in bringing in WBCs during inflammatory response Ito Cells Located within the space of the Disse (between the cords of hepatocytes) Satellite hepatocytes Function as storage for fat and Vitamin A Liver Cell Types Kupffer Cells In the sinusoids of the liver Specialized macrophage cells Responsible for cleaning out bacteria from the blood of the hepatic portal system; also removes worn-out RBC and recycles the hemoglobin Gall Bladder Surface Epithelium of the gall bladder Columnar cells and Goblet cells Columnar cells aid in absorption; Goblet cells secrete mucus Smooth muscle layer Contract to expel bile Serous Coat Outer Layer of Cells Protection for the gallbladder Pancreas Cells Pancreatic Acinar Cells (Serous Cells) Located within the pancreas Glandular epithelial cells with a high concentration of ribosomes on rough endoplasmic reticulum Function to release enzymes that assist in digestion Endocrine Cells – discussed in the endocrine cell lecture