Digestive System Flashcards
Describe the Oral Cavity
- lips, cheeks, palate, pharynx, and tongue
- lined by stratified squamous epithelium
- lamina propria of connective tissue
- no submucosa
- dental pad in ruminants with keratinized layer
Describe the Tongue
- covered by mucosa of stratified squamous epithelium
- keratinized on dorsal side, and have papillae
- main component is skeletal muscle in three directions
- lamina propria of loose CT and glands
- no submucosa
What are the hard structures of the tooth, and what cells produce each?
- enamel covers external surface, produced by ameloblasts
- dentin is beneath enamel, produced by odontoblast
- cementum, produced by cementoblasts
What are the soft tissues of the tooth, and what cells produce each?
- tooth pulp is loose CT and nerves in the center of the tooth, derived from neural crest cells
- periodontal ligament holds onto the tooth, produced by fibroblasts
What are the possible tunics in generic tubular organs?
- tunica mucosa: epithelium, lamina propria, and muscularis mucosa
- tunica submucosa
- tunica muscularis: inner circular and outer longitudinal
- tunica serosa: lined by mesothelium, adventitia is adhered to another tissue
Describe the layers of the esophagus
- mucosa: stratified squamous, loose CT, and muscularis mucosae
- submucosa: mucous glands
- muscularis: two layers of skeletal and/or smooth muscle
- adventitia: loost CT without mesothelium, most of esohpagus
- some is serosa, continuous with peritoneum
What type of epithelium lines the forestomachs in the ruminant?
- stratified squamous
- keratinized in reticulum
What type of epithelium lines the gastric glands?
simple columnar
What are the types of gastric glands?
- cardiac: mucous
- proper gastric: parietal and chief cells
- pyloric: mucous
What are the glandular regions and the components of them?
- cardiac: mucous glands and few parietal cells
- fundic: proper gastric glands; parietal and chief cells
- pyloric: mucous glands and G cells
What is produced by each of these cells?
Parietal, Chief, and G cells
- parietal: HCl (hydrochloric acid)
- Chief: pepsinogen
- G: gastrin
Describe Chief cells
- basophilic, granular cytoplasm
- dense, basally located nucleus
- also called peptic cells
- secrete pepsinogen
Describe Parietal cells
- acidophilic
- centrally located nucleus
- large and rounds cells
- secrete HCl and intrinsic factor
What type of epithelium lines the intestines?
simple columnar with goblet cells, enteroendocrine cells, and paneth cells
What are the features of the small intestine?
- plicae, villi, and microvilli
- villi with crypts of Lieberkahn and lacteals
- submucosal glands in duodenum
- Peyers patches in jejunum and ileum
What are the features of the large intestine?
- no villi
- absorbs H2) and secreted mucous
- longer crypts
- pigs and horses have taenia
Describe the location and features of Anal Sacs
- paired sacs located lateral and below the anus, between the internal and external sphincters
- lined by keratinized stratified squamous epithelium
What type of glands are the Anal Glands?
- apocrine in dogs
- apocrine and sebaceous in cats
What type of glands are the Circumanal Glands?
- sebaceous in the upper portion
- non-sebaceous (hepatoid glands) in the lower portion
What is the secretory unit of a gland?
adenomere
What is the space of Disse?
site of exchange between blood and hepatocyte
What is the function of the hepatocyte?
stores lipids and carbohydrates as triglycerides and glycogen
Describe a hepatic lobule
- hexagonal shape
- central vein in center
- portal triads at edges
- blood flows towards central vein, bile flows towards portal triads
- Kupffer cells (macrophages) adjacent to sinusoids
What is a portal lobule?
- physiological unit of the liver
- triangular area with portal triad in center
Describe the zones of the hepatic acinus
Zone 1: perilobular, high O2, nutrients, and pathogen exposure
Zone 2: moderate O2, nutrients, and pathogen exposure
Zone 3: centrilobular (nearest to central vein), low O2, nutrients, and pathogen exposure
Describe the Gallbladder
- stores bile from cystic duct
- abundant mucosal folds
- simple columnar epithelium with microvili
- no lamina mucularis mucosae
- serosa surround most of organ
Describe the stroma of the pancreas
- thin CT capsule and trabeculae with blood vessels, nerves, and lymph vessels
Describe the endocrine aspect of the pancreas
- 5% of parenchyma
- islets of Langerhan
- mostly B cells producing insulin
Describe the exocrine aspect of the pancreas
- 95% of parenchyma
- tubuloacinar secretory units
- drain into intercalated ducts lined by cuboidal cells
- interlobular ducts are not striated
- zymogen granules
- serous acinus
