Digestive System II

55 terms by stumpeb 

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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.

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