Histology Flashcards
what is the role of the oral cavity, teeth and tongue
mechanical processing, moistening, mixing with salivary secretion
what is the role of the salivary glands
secretion of lubricating fluid containing enzymes that break down carbohydrates
what is the role of the pharynx
pharyngeal muscles propel materials into the oesophagus
what is the role of the oesophagus
transport of material into the stomach
what is the role of the stomach
chemical breakdown of materials via acid ans enzymes
what is the role of the liver
secretion of bile (lipid digestion), storage of nutrients, many other vital functions
what is the role of the pancreas
exocrine cells secrete buffers and digestive enzymes
endocrine cells secrete hormones
what is the role of the gall bladder
storage and concentration of bile
what is the role of the small intestine
enzymatic digestion and absorption of water, organic substrates, vitamins and ions
what is the role of the large intestine
dehydration and compaction of indigestible materials in preparation for elimination
what cells cover the oral cavity, oropharynx and laryngopharynx
stratified squamous epithelium- generally not keratinized
what cells cover the nasal cavity and nasopharynx
respiratory epithelium
what cells cover the anterior 2/3 of the tongue
stratified squamous epithelium, thin on ventral (forward) surface, thick and with papillae on the dorsal (backwards) surface
what cells cover the posterior 1/3 of the tongue
smooth stratified squamous epithelium which (expect for the circumvallate) lacks papillae. Does have substantial lymphoid aggregates in the submucosa
what are the papillae of the tonuge
fungiform, circumvallate, foliate, filiform
what are the different structures present in the posterior 1/3rd of the tongue
stratified squamous epithelium, crypts, lymphoid tissue with some lymphoid follicles
(from the oesophagus to the anal canal) what are the 4 main layers of the GI tract from the lumen outwards
mucosa,
submucosa,
muscularis externa,
serosa/ adventitia
what are the three layers of the mucosa
epithelium (sits on a basal lamina) lamina propria (loose connective tissue) muscularis mucosae (thin layer of smooth muscle)
what is the submucosa
loose connective tissue
what is the muscularis externa
two thick layers of smooth muscle, an inner circular layer and an outer longitudinal layer
what is the serosa or adventitia
outerlayer of connective tissue that either suspends the digestive tract or attaches it to other organs
what are the holes in the epithelium called
gastric pits, at the bottom of these are gastric glands
what lines gastric pits
surface mucous cells
what are the parts of the from top to bottom
pit
isthmus (mostly parietal cells)
neck (mucous and stem cells)
base (chief, parietal, enteroendocrine cells)
what is the role of the chief cell
digesting enzyme secreting cell
what is the role of the parietal cells
hydrochloric acid producing cell
describe the mucosa of the cardia of the stomach
deep gastric pits that branch into loosely packed tortuous glands
describe the mucosa of the body of the stomach
shallow gastric pits with long straight gastric glands
describe the mucosa of the pylorus of the stomach
deep gastric pits with branched coiled gastric glands at a higher density than in the cardia
what is different about the muscularis externa of the stomach
in areas has additional layer which is oblique to the usual circular and longitudinal muscle layers, and is located internal to the circular layer. this layer aids in churning
describe the gastroduodenal junction
abrupt transition from stomach mucosa to duodenal mucosa. the inner layer of circular smooth muscle is markedly thickened to form the pyloric sphincter
what is seen on the surface view of the small intestine
villi and crypt of lieberkuhn
how long is the duodenum
25cm
how long is the jejunum
2m long
how long is the ileum
2.75m
where are peyers patches found
in the ileum
describe enterocytes
the most numerous, tall columnar cells with a brush border, the principle absorptive cells
describe goblet cells
produce mucin to protect epithelium and lubricate passage of material
describe paneth cells
Found at the base of the crypts of Lieberkuhn, they have a defensive function and have a role in regulating bacterial flora (secrete lysozyme and definsins)
describe enteroendocrine (neuroendocrine) cells
produce hormones that contribute to the control of secretion and motility (e.g. gastrin, cholecystokinin (CCK), vasoactive intestinal peptide (VIP)
describe stem cells
found at the base of the crypts of lieberkuhn, they divide to replenish epithelium
how is the duodenum different from any other part of the GI tract below the oesophagus
has glands within the submucosa called brunners glands which produce a thin alkaline mucous to neutralised the chyme
what type of tissue are peyers patches
lymphoid
what are the two principle cell types of the large intestinal epithelium
absorptive cells (remove salt and water) goblet cells (secrete mucous to lubricate the colon)
what is the appendix
blind ending hollow extension of the cecum
what is the 2-3cm of the anal canal continuous with
the stratified squamous epithelium of the surrounding skin
what controls gut motility
enteric nervous system, via myenteric plexus. most neurons in ganglia between two muscle layers of the muscularis externa
what is the submucosal plexus
second network of neurons found in the submucosa that controls the muscle of the muscularis mucosae and also helps regulate secretion in the epithelium