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37 Cards in this Set
- Front
- Back
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Describe Filiform Papilla
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– Small & conical – Most numerous, entire dorsal surface – No taste buds – Highly keratinized stratified squamous
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Describe Fungiform Papilla
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– Mushroom-shaped projections – More numerous at tip of tongue
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Describe Foliate papilla
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– Rows separated by deep clefts – Lateral edges of the tongue
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Describe Circumvallate papilla.
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– Large, dome-shaped – 8-12 anterior to sulcus terminalis – Moat-like invagination – Lingual salivary (von Ebner’s) glands, Serous
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What are the three cell types of taste bud.
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1. Neuroepithelial cells • Sensory • Synapse with afferent sensory neurons – Cranial nerve VII, IX or X • Each cell only expresses 1 class of receptor protein • Turnover time ~10 days 2. Supporting cells • Turnover time ~10 days 3. Basal cells • Stem cells • Located near basal lamina
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What tastes are coupled to G-proteins.
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– Bitter – Sweet – Umami
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Describe the 3 components of the mucosa layer.
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1. Epithelium 2. Lamina propria • Loose connective tissue • Blood & lymph vessels • Mucosal glands • Gut-associated lymphatic tissue (GALT) 3. Muscularis mucosae • Variable, usually 2 layers – Inner circular – Outer longitudinal • Contraction produces movement of the mucosa • Boundary between mucosa and submucosa
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Describe the 3 functions of the mucosa layer.
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3 principal functions 1. Protection • Barrier between lumen and tissues of the body 2. Absorption • Movement of digested nutrients, water & electrolytes into blood and lymph vessels 3. Secretion • Mucous, digestive enzymes, hormones & antibodies
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Describe the submucosa layer.
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• Dense irregular connective tissue • Larger blood & lymph vessels • Occasional glands – Esophageal glands proper – Duodenum (Brunner’s) glands • Submucosal (Meissner’s)plexus – Part of the enteric nervous system • Parasympathetic ganglia and postganglionic fibers • Innervate muscularis mucosae
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Describe the Submucosal Plexus
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Submucosal (Meissner’s)plexus • Pale staining parasympathetic ganglion cells (PG) • Scattered throughout the submucosa (SM)
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Describe the Muscularis Externa layer.
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2 concentric & thick layers 1. Inner circular • Contraction compresses and mixes contents • Forms sphincters at specific locations of the GI tract – Upper esophageal sphincter – Lower esophageal sphincter – Pyloric sphincter – Ileocecal valve – Internal anal sphincter 2. Outer longitudinal • Contraction propels contents by shortening the tube • Thickened in the large intestine – Bands called taenia coli
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What is the function of the Muscularis Externa layer.
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• Peristalsis – Slow, rhythmic contraction of muscle layers – Controlled by enteric nervous system • Myenteric (Auerbach’s) plexus – Part of the enteric nervous system – Parasympathetic ganglia and postganglionic fibers – Located between the 2 muscle layers
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Describe the Myenteric Plexus.
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• Pale staining parasympathetic ganglion cells • Located between inner circular (CM) and outer longitudinal (LM) muscle layers of the Muscularis Externa
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Describe the serosa layer.
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1. Simple squamousepithelium – Mesothelium
2. Small amount underlying connective tissue 3. Continuous with mesentery and lining of abdominal cavity |
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Describe the Adventitia layer.
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– Loose connective tissue
– Attaches structures to the body walls • Parts of the GI tract that do not possess a serosa – Thoracic esophagus – 2nd, 3rd & 4th parts of duodenum – Ascending & descending colon – Rectum & anal canal |
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Describe the muscularis externa layer of the esophagus.
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Muscularis externa – 2 muscle layers • Inner circular • Outer longitudinal • Upper 1/3 striated muscle • Middle 1/3 striated muscle & smooth muscle • Lower 1/3 smooth muscle – Myenteric (Auerbach’s) plexus • Between inner and outer muscle layers • Nerve fibers and ganglion cells • Innervates muscularis externa
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Describe Barrett’s Esophagus
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Reflux through the sphincter, allows gastric acid into the lower esophagus. Lower esophagus undergoes metaplasia – Change in differentiation of cells – Stratified squamous converts to secretory simple columnar epithelium High risk of developing dysplasia – Cellular atypia • Failure of differentiation
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Describe the three histological regions of the stomach?
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1. Cardiac region (cardia) • Surrounds esophageal orifice • Contains cardiac glands 2. Fundic region (fundus) • Situated between cardia and pylorus • Contains fundic (gastric) glands 3. Pyloric region (pylorus) • Distal, funnel-shaped • Proximal to pyloric sphincter • Contains pyloric glands
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What are rugae?
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Longitudinal mucosal folds in the stomach.
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Describe cardiac glands.
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– Relatively short pits & short glands – Tubular with occasional branching – Cells • Mucous-secreting • Enteroendocrine
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Describe pyloric glands.
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– Relatively long pits and short glands – Branched, coiled, tubular with wide lumen – Cells • Mucous-secreting – Resemble surface mucus cells – Viscous • Enteroendocrine • Occasional parietal
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What do parietal cells make?
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HCL
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What do Chief cells make.
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Pepsin
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What cells are found in a Fundic (Gastric) Glands?
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4 functional cell types 1. Neck mucous cells – Renewed every 5-6 days 2. Parietal cells (oxyntic) – Renewed every 150-200 days 3. Chief cells (peptic) – Renewed every 60-90 days 4. Enteroendocrine cells – Renewed every 60-90 days
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What is the function of the intrinsic factor secreted by parietal cells?
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• Essential for B 12 absorption in the distal ileum • Lack of intrinsic factor results in pernicious anemia & vitamin B 12 deficiency
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What are the Distinguishing characteristics of the Duodenum?
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– Submucosal glands • Brunner’s glands (BGl)
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What are Plicae circularis?
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Folds in the small intestine.
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What are the distinctive features of the jejunum?
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– Numerous plicaecircularis – Long prominent villi – Increase in goblet cells – No submucosal glands
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What are the Distinguishing characteristics of the Ileum.
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– Aggregated nodules of lymphatic tissue in lamina propria • Peyer’s patches • Especially numerous in ileum
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What are the 5 cell types found in the small Intestine?
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1. Enterocytes – Intestinal absorptive cells – Renewed every 4-6 days 2. Goblet cells – Unicellular mucous secreting cells – Renewed every 4-6 days 3. Paneth cells – Secretes antimicrobial substances – Renewed every 4 weeks 4. Enteroendocrine cells – Produce paracrine and endocrine hormones – Renewed every 60-90 days 5. M cells – Microfold cells – Modified enterocytes – Cover enlarged lymphatic nodules
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Describe Enterocytes
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Simple columnar – Microvilli • Striated border – Tight junctions • Allow for selective absorption across the plasma membrane – Lateral plications • Increase lateral surface area • Primarily absorptive cells • Also produce digestive enzymes – Inserted into the apical plasma membrane
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Describe Paneth Cells.
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• Found in base of intestinal glands • Basophilic basal cytoplasm • Intensely acidophilic apical secretory vesicles – Lysozyme • Antibacterial enzyme • Digests cell walls of certain groups of bacteria – α-defensins • Microbicidal peptides • Role in regulation of normal bacterial flora in small intestine
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Describe Enteroendocrine Cells.
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• Produce some of the same peptide hormones as stomach • Most active regulators of GI physiology released in the small intestine – CCK – Secretin – GIP – Motilin
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Describe M Cells
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• Epithelial cells that cover Peyer’s patches and large lymphatic nodules • Microfolds on apical surface rather than microvilli • Antigen-transporting cells – Take up microorganisms & macromolecules from lumen – Transport vesicles to basolateral cell membrane – Discharge vesicle contents into intercellular space – Substances interact with cells of GALT
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What is the Teniae coli?
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Prominent longitudinal bands of
longitudinal muscle located in the muscularis externa |
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Centroacinar cells are a characteristic of the?
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Exocrine pancreas
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Bile canaliculi are?
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Are a continuous network of minute channels that run between hepatic cells.
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