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111 Cards in this Set
- Front
- Back
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What are the primary layers of the Digestive Tract?
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Mucosa (mucous membrane)
Submucousa Muscularis Serosa |
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What tissue is found in the mucosa layer of the digestive tract?
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Epithelium
Lamina propria Muscularis mucosa |
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What is the function of the epithelium found in the digestive tract?
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Highly selective for absorption, promotes digestion, produces hormones, produces mucous for lubrication and protection of other cells
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What layer of the mucosa promotes movement to propel and mix food?
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Muscularis mucosa (inner circular and outer longitudinal smooth muscle
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What is found in the submucosa layer of the digestive tract?
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Dense connective tissue w/ many blood and lymph vessels, glands and lymphoid tissue
submucosal(meissner's) autonomic nerve plexus |
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Where is the myenteric (Auerbach's) autonomic nerve plexus found?
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in the muscularis layer of the digestive tract
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What lines the oral cavity
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stratified squamous epithelium (karatin & non-karatinized)
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Where is non-karatin stratified squamous epithelium found in the oral cavity
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soft palate, lips, cheeks and floor of mouth
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Where is karatinized stratified squamous epithelium found in the oral cavity?
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hard palate and gums
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How is the tongue divided?
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1/2 posterior end containing lingual tonsils
2/3 anterior end Separated by a V shaped boundary |
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What are the types of papillae on the tongue?
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Filiform
Fungiform Foliate Circumvallate |
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Which type of papillae contains taste buds?
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circumavallate
Fungiform Foliate |
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Which type of papillae contains no taste buds?
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filiform
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What is the function of the taste bud?
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to detect saltiness, sourness, sweetness, bitterness
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What type of cells are found in the taste bud?
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taste pores, taste cells w/microvilli, and supporting cells
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What type of tissue is found lining the pharynx?
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non-keratinized statified squamous epithelium
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What structures does the pharynx contain?
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palatine tonsils and mucous salivary glands
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What is the role of the circular and longitudinal layers of skeletal muscles in the pharynx
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form the supportive wall of the pharynx (constrictor muscles
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How many teeth do adults have?
Children? |
Adults - 32 permanent teeth
Children - 20 deciduous teeth |
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What are the external regions of the tooth?
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Crown - part of tooth above gingiva
Neck - region near the gumline Root - part of tooth below gum |
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__________ covers crown of tooth
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Enamel
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___________ covers roots of tooth
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cementum
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what is the part of the tooth where enamel and cementum meet?
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The cervix
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________ surrounds the pulp cavity and rootcanal, and deep to the enamel and cementum
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Dentin
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Contains odontoblasts, fibroblasts, thin collagen fibrils, ground substance and blood vessels
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pulp cavity
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Where are Sharpey's fibers found?
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peridontal ligament
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What is the function of the peridontal ligament?
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anchor the cementum of tooth firmly into the surrounding alveolar bone
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What is found in Dentin?
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type I collagen, fibrils, glycosaminoglycans, phophoproteins, phospholipids and calcium salts (hydroxyapatite crystals)
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What secretes the organic matrix of dentin?
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odontoblasts
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What is the hardest component of the body?
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enamel
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What are the components of enamel?
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96% mineral, 1% organic matter, 3% water
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What secretes the matrix of the enamel?
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ameloblasts
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What is the structure that connects the laryngopharynx to the stomach?
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Esophagus
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What lines the esophagus?
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mucosa is non-keratinized stratified sqamous
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What layers are present in the mucosa of the espohagus?
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epithelial
lamina propria (containing mucus secreting esophageal cardiac glands near stomach) muscularis mucosa |
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What is the function of the mucus-secreting esophageal glands?
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to facilitate transport of food and protection of mucosa
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What are the differences in the muscularis mucosa as you descend the esophagus?
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Upper 1/3: skeletal muscle
Middle 1/3: mixture of skeletal and smooth Lower 1/3: mostly smooth muscle |
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How would you describe the esophageal sphincter?
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A thickening of circular muscle layer near the opening of the stomach
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What is the outer layer of the esophagus called?
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serosa or adventitia
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What is the function of the stomach?
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mixed exocrine/endocrine organ that digests food and secretes hormones
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Specifically what does the stomach do?
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Continues digestion of carbs
Adds acidic fluid to ingested food Transforms ingested material into viscous chyme Promotes inital digestion of proteins w/ pepsin Produces gastric lipase to assist digestion of triglycerides |
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What are the gross regions of the stomach?
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cardia, fundus, body, pylorus
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What two gross regions are histologically similar?
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fundus and body
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What feature is present the undistended stomach, but not in distended stomach?
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rugae
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Describe mucosa layer in stomach
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simple columnar epith. w/invaginations (gastric pits)
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What is the purpose of the mucus gel secreted by all cells in the stomach
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defense (adheres firmly to epithelial cells)
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Which cells in the stomach secrete bicarbonate?
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surface epithelial cells
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In what direction are the muscularis arranged in the stomach?
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3 directions
external is longitudinal, middle is circular, internal is oblique |
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Where is the cardia region found in the stomach?
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Narrow circular band between esophagus and remainder of stomach
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What type of glands are found in the mucosa of the cardia region?
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simple or branched tubular cardiac glands which produce mucus and lysozome.
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What type of glands are found in the fundus region of the stomach?
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3-7 gastric glands that open into the bottome of each gastric pit
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Name the cells (5) found in the gastric glands of the fundus/body?
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stem cells, mucous neck cells, parietal(oxyntic)cells, enteroendocrine cells, chief cells
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Where are stem cells found in the gastric glands
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found in isthmus and neck regions
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What are feature of stem cells found in the gastric glands?
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Low columnar w/ nuclei near their bases
high rate of mitosis Some ascend to replace the pit & surface mucous cells, other differentiate into other cells |
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Where are mucous neck cells found?
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in clusters (or singly) between parietal cells of the necks of gastric glands
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What is the function of mucous neck cells?
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to secrete mucus (which is different that surface mucus)
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What is function of parietal cells?
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secrete H+ and Cl-, potassium chloride and other stuff which is impt in Vit B12 metabolism
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Where are parietal cells found in the gastric glands?
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mostly in upper half
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What is histological description of oxyntic cells?
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rounded or pyramindal w/large nucleus, and pink cytoplasm. Contain many mitochondria and a deep invagination of apical membrane
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What is another name for parietal cells?
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oxyntic cells
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What is the function of enteroendocrine cells in the stomach?
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to porduce serotonin primarily in fundus
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What is another name for the zymogenic cells?
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chief cells
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Where are chief cells found?
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lower regions of gastric glands
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What is found in the granules of chief cells?
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pepsignogen
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What will chief cells in humans secrete?
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lipase (along with other proteins)
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What is different with the gastric pits in the pylorus vs the fundus?
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the pits in the pylorus are deeper than in the fundus
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What is characteristic of pyloric glands?
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shorter coiled secretory portions
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What does the pyloric gland secrete?
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mucus and lysozyme
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What type of cells are found in the pyloric glands?
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G cells - enteroendocrine cells
D cells - enteroendocrine cells |
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What does the G cell secrete?
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gastrin which activates parietal cell production of HCL
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What is the function of the D cell?
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secrete somatostatin which inhibits gastrin secretion, thereby decreasing HCl production
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What is the function of the small intestine?
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Site of terminal food digestion, nutrient absorption and endocrine secretion
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How long is the small intestine?
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about 5 meters
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What are the gross regions of the small intestine?
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duodenum, jejunum, ileum
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What are teh permanent fold in the mucosa and submucosa of the small intestine called?
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plica circulares
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Where are the plica circulares most developed?
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jejunum
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What type of tissue are intestinal villi composed?
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outgrowths of simple columnar epith. and lamina propria
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What is found between intestinal villi?
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openings to the intestinal glands
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What are M cells?
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specialized epth. cells overlying lymphoid follicles of peyer's patches
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What is the function of the M cells?
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endocytose antigens and transport them to underlying macrophages and lymphoid cells
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What feature facilitates the transit between M cells and cells in lamina propria?
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An incomplete basal lamina
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What type of cells are found in the epithelial layer of small intestine that release secretory granules by exocytosis?
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endocrine cells
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What is contained in the lamina propria of the small intestine?
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loose connective tissue w/ blood and lymph vessels, nerve fibers and smooth muscle fibers
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What is found in the submucosa of the small intestine?
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clusters of duodenal glands
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What do the duodenal glands secrete and why?
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mucous and alkaline to protect the duodenal mucous membrane an dto provide optimum pH for pancreatic enzyme action
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Describe muscularis layer of small intestine?
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inner circular layer and outer longitudinal layer of smooth muscle
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Outer layer of small intestine is called?
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serosa
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What is histological feature of the absorptive cells?
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Tall columnar cell with an oval nucleus
Brush border on apex and core of actin microfilament |
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By what factor is surface area increased with the absorptive cell's physical features?
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about 600 fold
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What is secreted by absorptive cells?
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Disaccharides and peptidases
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What do absorptive cells absorb?
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lipids
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What does the goblet cell secrete and why?
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mucus to protect mucosal lining
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Where are goblet cells found?
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epithelial layer of small intestine, interspersed between absorptive cells. Less abundant in douodenum but increases toward ileum
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Where are paneth's cells located?
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at basal portion of intestinal glands
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What do paneth's cells contain?
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Large amounts of RER, large eosinophilic secretory granules which contain lysozyme
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Through what network are nutrient absorbed in small intestine?
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capillary network, to veins that eventually drain into the liver via the hepatic portal vein
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Through what network are lipids absorbed in the small intestine?
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A lacteal absorbs lipids, draining into larger lymph vessels and eventually leading into the cisterna chyli of lymphatic system
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What is the function of the large intestine?
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absorption of water, and formation of fecal mass and production of mucus.
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How long is the large intestine?
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approx. 6 feet (2 meters)
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What are the gross regions of the large intestine?
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cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum and anus
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Where are fold found in the large intestine?
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in the rectal region called rectal columns
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Are there villi in the large intestine?
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No
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What is the lining of the large intestine composed of?
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simple columnar epithelium except in the anal region which has keratinized stratified squamous
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What is the histological description of the intestinal glands?
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long and have many goblet and absorptive cells and few enteroendocrine cells
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What is found in the lamina propria of the large intestine?
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large amounts of GALT. In the anal region also contains a plexus of large viens
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What is found in the muscularis layer of the large intestine?
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complete inner layer of smoothmuscle and 3 incomplete thick longitudinal bands of smooth muscle (teniae coli)
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What is the teniae coli?
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3 incomplete thick longitudinal bands of smooth muscle found in the large intestine
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What is found in the serous layer of the large intestine
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tabs of adipose tissue (appendices epiploicae)
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What is the appendix
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Evagination of the cecum
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What is found in the appendix?
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large amounts of lymphoid follicles
fewer and shorter intestinal glands no teniae coli |
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How is cell renewal performed in the digestive tract?
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stem cells produce new cells constantly by mitosis
They will migrate and differentiate into other cell types |
