Lecture 11 - Digestive Tract Flashcards
how are accessory organs and gland connected to the muscular tube?
via duct
def: prominent aggregations of lymphoid tissue within the digestive system
gut-associated lymphoid system (GALT)
def: includes the epithelium, supporting lamina propria and thin smooth muscle layer: muscularis mucosae which produce local movement and folding
mucosa
def: thick connective tissue layer that contains glands, arteries, veins, lymphatics, and nerves
submucosa
def: surrounds the submucosa and is composed of two muscle layers: inner circular and outer longitudinal, they move perpendicularly to one another in peristalsis
muscularis externus
def: consists of connective tissue contains blood vessels, nerves, fat, lined by mesothelium in portions of the tract within the peritoneal cavity
serosa/adventitia
what are the 4 types of papillae on the dorsal surface of the tongue?
- filiform
- fungiform
- circumvallate
- foliate
def: elongated, conical shape, heavily keratinized, lack taste buds, provide rough surface or movement of food in chewing
filiform papillae
def: mushroom shaped, lightly keratinized, contain a few taste buds
fungiform papillae
def: large and dome shaped, contain most of the taste buds on the tongue
circumvallate papillae
def: continuously flushing taste buds to remove food particles and allow taste buds to process new stimuli
serous glands
def: ovoid structures, each containing 50-75 cells, within the stratified epithelium of the tongue and the oral mucosa
taste buds
how often do gustatory cells turn over
7-10 days
what are the five categories of tastants?
- metal ions = salty
- hydrogen ions = sour
- sugars = sweet
- alkaloids = bitter
- amino acids such as glutamate = umami
salty and sour tastes produced by what kind of channels and other taste categories are mediated by what kind of receptors?
salty and sour = ion channels
other tastes = G-protein-coupled receptors
what kind of protective epithelium is in the mucosa of the oral cavity, pharynx, esophagus, and anal canal
stratified squamous epithelium
what are the 3 divisions of muscle in the esophagus?
- skeletal muscle in the proximal esophagus
- mixed skeletal muscle in the middle
- smooth muscle in the distal esophagus
def: where the esophagus ends, an abrupt transition from stratified squamous epithelium in the esophagus to simple columnar epithelium in the stomach
gastro-esophageal junction
def: columnar epithelium of the stomach replaces the usual stratified squamous epithelium of the esophagus
Barrett’s esophagus
def: basic secretory unit of the stomach
gastric gland
def: cells that secrete intrinsic factor
parietal cells
def: cells that secrete pepsinogen
chief cells
what lines gastric pits?
simple columnar epithelium
where does the stomach become the duodenum?
the gastroduodenal junction
def: identifiable by long gastric pits and glands, containing mucous secreting cells
pyloric stomach
def: broad intestinal villi, separated by crypts and containing goblet cells
duodenum
def: make up a brush border on the surface of columnar cells of the mucosal epithelium
microvilli
def: finger-like projections of the epithelium and lamina propria that project into the lumen
villi
def: folds of the mucosal epithelium, lamina propria, muscularis mucosa and submucosa that projects into the lumen, are the most prominent in the jejunum
plicae circulares
Brunner’s glands are only found in the _______________-
duodenum
the villi tend to be longest in the __________ and become shorter towards the _____________
duodenum, ileum
lymphoid tissue becomes more prominent in the _________ and is limited in the _______________
ileum, duodenum
the proportion of goblet cells in the epithelium increases ___________
distally
Plicae circulares are most prominent and numerous in the ______________ and proximal __________ and are generally absent in the proximal ________________ and distal ____________
jejunum, proximal ileum, proximal duodenum, distal ileum
def: glands that produce alkaline mucous, they fill the submucosa and open into the mucosa to drain into the lumen
Brunner’s glands
def: aggregates of lymphoid cells that provide immuno-surveillance and limit growth of pathogenic bacteria
Peyer’s Patch
def: absorptive cells, tall columnar cells, each with an oval nucleus in the basal half of the cell
enterocytes
goblet cell frequency increases from ________ to __________
proximal (duodenum) to distal (ileum)
def: located in the basal portion of the intestinal crypts below the stem cells, are exocrine cells with large, eosinophilic secretory granules in their apical cytoplasm, contain enzymes and other proteins that act on bacteria contributing to innate immunity
Paneth cells
what lines the large intestine?
mucosa is lined by columnar epithelium with small brush border and many goblet cells
are there villi and plicae circularis in the large intestine?
no
def: plexus between inner and outer layers of smooth muscle in the muscularis externa, mainly regulates smooth muscle contraction, peristalsis, and gastrointestinal motility
myenteric (Auerbach) plexus
def: smaller plexus mostly regulates glandular secretion and membrane transport
submucosal (Meissner) plexus
parasympathetic nerve fibers usually _________ digestion
activate
sympathetic nerve fibers usually _________ digestion
inhibit
what are the 3 main functions of the liver?
- metabolism of carbs, proteins and fats
- modification of exogenous substances such as drugs and alcohol
- formation and exocrine secretion of bile
what is the functional unit of the liver?
hexagonal lobules that hepatocytes are arranged in
each lobule surrounds a central vein and is bound by __ _________ _______
6 portal triads
how does blood flow through each lobule?
centrally toward the central vein and eventually drains into the IVC
how does bile flow through each lobule?
peripherally, produced by hepatocytes and collected in the duct
both the portal vein and the hepatic arteries drain into _________ ___________ such that blood in the liver makes intimate contact with hepatocytes
fenestrated sinusoids
which zone of the hepatic acinus is this: farthest away and is the site of most alcohol and drug detoxification
zone 3
which zone of the hepatic acinus receives oxygen first?
zone 1
