lect 32 & 33-Upper GI histology Flashcards
what is the epithelium of the GI tract
stratified squamous at either end
simple columnar most of the length
what type of muscle is in the GI tract
skeletal at either end (including upper esophagus)
smooth muscle throughout most of length
what is the GI intrinsic rhymicity mostly due to
presence of an enteric nervous system that exists independently of external influences including ANS
what are the peptide neurotransmitters
bombesin
motilin
vasoactive intestinal peptide
what do unicellular endocrine cells secrete
secrete neuropeptides
what are unicellular endocrine cells derived from
endoderm
what are intrinsic nerve fibers derived from
neural crest
what does the mucus membrane of the lip consist of
stratified squamous epithelium
basement membrane
lamina propria
what 3 embryonic tissues interact in the development of teeth
ectoderm, neural crest and mesoderm
what gves rise to dental papilla
neural crest and mesoderm
what forms the enamel organ
ectoderm
what is the dental primordium formed from
basal cels of the oral ectoderm
what is the labiodental lamina
epithelial shelf that grows from the thickening primordial into the mesenchyme as a bifid structure
what is the dental lamina
internal limb (teeth)
what is the dental sac
CT sac surrounding the enamel organ and dental papilla and forms cementum and the periodontal membrane
what forms the dentin matrix through the life of the tooth
odontoblasts
define tomes’ dentinal fibers
cytoplasmic extensions of the odontoblasts continuing through the predentin and dentinal layers to the dentin-enamel junction
what type of collagen in dentin primarily composed of
collagen type 1
what forms the enamel which covers only the tooth crown
ameloblasts
what is the hardest substance in the body
enamel
what organic components are unique to enamel and are removed after calcification
amelogenins and enamelins
what does pulp originate from
dental papilla containing condensed mesenchyme
what is the periodontal membrane
CT formed from dental sac with fibroblasts, osteoblasts, cementoblasts, collagen fibers, blood vessels and nerve vessels
what binds the cementum to the bony socket
periodontal membrane
what separates the anterior 2/3 of the upper oral portio of the tongue from the posterior 1/3
sulcus terminalis
what are lingual papillae formed of
central core of CT lamina propria covered by stratified squamous epithelium
what are the 2 types of cells of taste buds
sustantacular cells and taste cells
what are sustentacular cells
taste bud cells that are spindle-shaped support cells and arranged like barrel-staves to surround the inner taste pore at the base
what does the basal part of taste cells secrete
neurotransmitters
what do salt and sour taste sensations use as a signal transduction mechanism
ionic transport
what does sour taste sensation involve
hydrogen ion blockage of potassium ion channels to cause depolarization
what does bitter taste involve
gustucin (homologue of retinal transducer)
involves activates of Galpha subunit, decrease in cGMP, and closure of sodium channels and hypo polarization of the taste cells
what type of epithelium is in the mucosa of the digestive tube
stratified squamous transitioning to simple columnar
what type of tissue is in the lamina propria of the digestive tubule
loose areolar CT associated with epithelium
what type of tissue in in the submucosa of the digestive tube
dense, irregular CT
what nerve plexus is located in the submucosa of the digestive tube
meissner’s plexus
what are the functions of muscular is externa
regulates size of lumen
regulates rhythmic movement of GI tract
what is tissue of the serosa of the digest tube
dense irregular CT
layer of submesothelial Ct
what time of tissue is in the adventitia of the digestive tube
dense irregular CT with adipose tissue
what is the sympathetic innervation of the gut wall
sympathetic postganglionic fibers pass through gut wall to glands and smooth muscle
what is the parasympathetic innervation of the gut wall
preganglionic fibers synapse with postganglionic fibers in ganglia within the gut wall itself
what does the meissner’s plexus regulate
local secretion, blood flow and absorption
what does the auerbach’s plexus do
coordinates muscular activity of gut wall
what is the first line of defense in the gut-associated lymphoid tissue
IgA
what secretes IgA
antigen-stimulated B cells in the follicle of the lamina propria
what are the functions of the esophagus
digestion (initiated in the mouth)
addition of mucous to food bolus
what type of epithelium is in the mucosa of the esophagus
stratified squamous nonkeratinized epithelium
what are rugae
longitudinal mucosal folds that are most prominent in an empty stomach
where do gastric glands open into
gastric pits
what type of glands does the cardia of the stomach contain
mostly mucous glands
what type of glands are in the funds of the stomach
gastric glands
what type of glands are contained in the body of the stomach
gastric glands
what type of glands are contained in the pylorus of the stomach
mucous glands and hormone-secreting enteroendocrine cells
what do chief cells secrete
pepsinogen
what do parietal cells manufacture
HCL
what secretes intrinsic factor
parietal cells
what do enteroendocrine cells do
diffuse neuroendocrine cells that secrete hormones and secrete serotonin
where are mucous neck cells located
in the narrow portion of the gland near the gastric pit
what type of epithelium lines the surface of the stomach and the pit
simple columnar consisting of surface mucous cells
where do chief cells predominate
end portion of gastric gland
how are parietal cells shaped
large pyramidal shaped, eosinophilic cells
what are common ways to increase surface area for absorption in GI tract
increase length of small and large intestines plicae circulares (valves of kerckring) villi and microvilli
define plicae
folds of the mucosa, each with a submucosal core
where do the crypts extend
down between the villi below the bases of the villi
what is the epithelium of the wall of villus in the crypt-villus system
simple columnar epithelium
what type of plexus does each villus have of the crypt-villus system
capillary plexus
what is the blind-ending lympathic in each villus called
lacteal
define glycocalyx
glycolipid coat that contains an array of brush border enzymes: maltose, sucrase, isomaltase, lactase, lipase, peptidases
what is glycocalyx produced by
small intestine epithelial cells (enderocytes)
what are the microvilli in the small intestine supported by
actin filaments
how are actin filaments tied to terminal web intermediate filaments
via spectrin fibrils
what membrane-linking proteins bind actin filaments to plasma membrane covering the villus
myosin I and calmodulin
what actin cross-linking proteins are used to bind actin filaments to each other
villain and fimbrin
