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55 terms

Digestive System II

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salivary glands
open into oral cavity, divided into minor and major; receive both sympathetic and parasympathetic innervation
minor salivary glands
scattered in submucosal CT of oral cavity. Include lingual, buccal, labial, pharyngeal, palatine.
major salivary glands
compound (grossly dissectable) glands encapsulated with thin septa between lobules. Typically compound tubuloacinar in organization.
parotid salivary gland
major salivary gland with predominately serous secretion
mandibular, sublingual, zygomatic, and molar salivary glands
major salivary glands that have mixed serous and mucous secretion
serous cells
secretory cells of salivary glands that form acini or demilunes which cap mucous acini.
acinar and demilune cells
serous cells with apical membrane bound granules and well developed RER and golgi
mucous cells
secretory cells of salivary glands that form acini or tubuloacinar units and have apical mucinogen granules, flattened basal nuclei, and basal RER and golgi
myoepithelial cells
secretory cells of salivary glands that have processes that surround both acini and intercalated ducts; located on epithelial side of basal lamina
intercalated ducts
smallest part of salivary gland duct system, comprised of pale cuboidal cells; very short and inconspicuous, and arise directly from acini
striated ducts
ducts in the salivary gland system that are lined by columnar cells and constitute a transport epithelium. Basal mitochondria are aligned between plasma membrane infoldings and basolateral interdigitating processes which provide increased membrane area for ion transport processes.
interlobular duct
part of excretory duct system with columnar to stratified cuboidal epithelium surrounded by a thin CT layer
main duct
terminal portion of excretory duct system, which may have stratified cuboidal epithelium; near duct opening the epithelium usually becomes stratified squamous.
protection of oral cavity and teeth; production of lubricant for dry ingesta; provide fluid for rumen, pH adjustment; source of IgA from adjacent plasma cells and hormones; production of digestive enzymes; regulation of electrolyte balance
functions of salivary glands
movement of ingesta through tube; digestion; absorption of simple nutrients; secretion of enzymes, hormones, and mucin
functions of GI tract
T. mucosa
layer that varies most in GI tract, mucous membrane layer
stratified squamous
epithelium in mouth, non-glandular stomach, anal canal
simple columnar
epithelium in glandular stomach through rectum
lamina propria
made up of fine collagen fibers, very cellular; abundant diffuse lymphatic tissue which may form solitary or aggregated lymphatic nodules (GALT)
muscularis mucosae
smooth muscle; 0-3 layers of smooth muscle located between the T. mucosa and the T. submucosa
mucosal glands
found from glandular stomach through rectum; glandular structure and cells vary with organ
villi
mucosal projections which increase surface area; characteristic of small intestine
T. submucosa
coarse CT; contains glands in some parts of esophagus and duodenum; contains larger blood vessels, nerves, and lymphatic vessels; may contain lymphatic nodules and many free cells
submucosal nerve plexus
in T. submucosa, contains sympathetic and parasympathetic fibers, and parasympathetic terminal ganglia
T. muscularis
generally two layers of smooth muscle, but may be striated at either end; inner circular muscle layers form sphincters; outer longitudinal muscle layer may form longitudinal bands
myenteric plexus
between muscle layers of T. muscularis, contains parasympathetic terminal ganglia and autonomic ganglia
T. adventitia
an ill-defined layer of CT blending with surrounding CT
T. serosa
thin CT layer covered by mesothelium (a simple squamous epithelium), e.g. visceral peritoneum
esophagus
a highly distensible organ due to longitudinal folds and elastic fibers in lamina propria and submucosa
T. mucosa of esophagus
epithelium is stratified squamous, and is keratinized in herbivores and pigs
mucularis mucosae of esophagus
has longitudinal orientation and may be absent or sparse cranially (pig and dog). This layer increases in thickness caudally (especially in pig)
T. submucosa of esophagus
contains tubuloacinar glands which are mostly mucous with some serous demilune cells. Glands are only found cranially (except in dog where glands extend to stomach)
T. muscularis of esophagus
muscle layers are inner circular and outer longitudinal; striated muscle found along entire length in dog and ruminants; striated muscle found cranially only and smooth muscle replaces it caudally in cat, pig, horse; circular layers modified to form physiological sphincter at pharyngeal-esophageal and esophageal-gastric junctions.
T. adventitia
covers most of the length of the esophagus
storage and mixing; mechanical and chemical digestion; secretion of mucous, enzymes, H2O, electrolytes, hormones
functions of simple glandular stomach
cardiac gland region
region of simple stomach found near esophagus, may be quite small; contains predominantly mucous cells; pits and glands may be relatively short in comparison to other regions and have wide lumen
pyloric gland region
region of simple stomach that is predominantly mucous cells; generally deepest pits and short coiled glands; thickest T. muscularis
fundic gland region
region of simple stomach that is largest (except in pig); greatest variety of cell types in glands
non-glandular area
found in simple stomach of horse and pig, lined by stratified squamous epithelium
gastric folds
divisions of T. mucosa of empty stomach
gastric pits
depressions in stomach luminal surface
tall columnar
gastric epithelium lining gastric pits
gastric glands
openings found at base of gastric pits; simple branched or coiled tubular
lamina propria of stomach
sparse and contains fine collagen fibers and free cells between gastric glands; usually contains varying amounts of diffuse lymphoid tissue
subglandular layer
layer found in stomach of carnivores and may protect against perforation and microbial invasion; located at border between lamina propria and muscularis mucosae
stratum granulosum and stratum compactum
two parts of subglandular layer of carnivore stomach
stratum granulosum
very cellular part of subglandular layer of carnivore stomach
stratum compactum
part of subglandular layer of carnivore stomach that consists of packed collagen fibers
muscularis mucosae of stomach
generally comprised of 3 layers of smooth muscle; strands of smooth muscle from the inner most layer extend between glands toward the mucosal surface.
T. submucosa of stomach
contains coarse CT, abundant free cells and largest blood vessels and submucosal plexus
T. muscularis of stomach
has 3 layers of smooth muscle: inner oblique, middle circular which gives rise to sphincters, outer longitudinal layer
T. serosa
covers outermost surface of stomach
luminal gastric surface and gastric pit epithelial cells
columnar mucus secreting cells of the stomach
gastric gland cells
cells of the stomach that are replaced by mitoses occurring in the gland neck region.
gastric mucosal barrier
protects gastric mucosa from acid stomach contents and from physical damage; composed of alkaline mucus and HCO3 secreted by epithelial cells and the tight junctions between cell apices.