Histology Flashcards
epithelium covering oral cavity, oropharynx and laryngopharnyx
stratified squamous epithelium
not ketarinized
epithelium covering nasal cavity and nasopharnyx
respiratory epithelium
anterior tongue
stratified squamous epithelium;
thin on ventral surface
thick and with papillae on dorsal surface
posterior tongue
smooth stratified squamous epithelium
lacks papillae, with exception of circumvallate papillae
circumvallate papillae has substantial lymphoid aggregates in submucosa
papillae of tongue
anterior to posterior; fungiform circumvallate foliate filiform - no tastebuds
lymphoid tissue of the pharnyx
composed of palatine tonsils
lingual tonsils
tubal tonsils
pharyngeal tonsils (adenoids)
4 layers of digestive tract
mucosa
submucosa
muscularis externa
serosa/adventitia
mucosa
3 parts;
epithelium - sits on basal lamina
lamina propria - loose connective tissue
muscularis mucosae - smooth muscle
submucosa
connective tissue
muscularis externa
2 thick layers of smooth muscle
inner circular layer
outer longitudinal layer
serosa/adventitia
connective tissue - suspends digestive tract or attaches it to other organs
variations of oesophagus
contains submucosal glands
transition of epithelium from oesophagus to stomach
abrupt transition from stratified squamous epithelium to simple columnar epithelium of the cardia of stomach
stomach
contains gastric pits lined by surface mucous cells on epithelium
gastric glands at bottom of gastric pits
cells of the gastric glands - isthmus
parietal cells
stem cells
cells of the gastric glands - neck
neck mucous cells
parietal cells
cells of the gastric glands - fundus (base)
chief cells
few parietal cells
enteroendocrinecells (neuroendocrine cells)
chief cells
digestive enzyme secreting cell
parietal cell
hydrochloric acid producing cell
regions of the stomach
cardia
body
pylorus
cardia of the stomach
deep gastric pits that branch into loosely packed, tortuous glands
body of the stomach
shallow gastric pits with long straight gastric glands
pylorus of the stomach
deep gastric pits with branched, coiled gastric glands at a higher density than in the cardia
muscularis externa of stomach
contains additional layer - aids churning of stomach
extra layer is oblique to usual circular and longitudinal muscle layers
located internal to circular layer
transition from stomach to duodenum
abrupt transition from stomach mucosa (mucous) to duodenal mucosa (absorptive)
inner, circular layer of smooth muscle is thickened to form pyloric sphincter
small instestine
finger-like projections - villi between bases of adjacent villi are pits drilling downwards - crypts of lieberkuhn made up of; deudenum jejunum ileum
deudenum
receives acidic, partly digested semifluid –> chyme from stomach
differs from other regions of GI tract below the oesophagus as it has glands within the submucosa –> Brunner’s glands
when stimulated by the presence of chyme they produce a thin, alkaline mucous to neutralise the chyme.
25cm
jejunum
tallest villi, located on permanent circular folds of mucosa and submucosa, the plicae circularis (also contains submucosa)
lymphoid follicles infrequent
2m
ileum
shorter vili
aggregations of lymphoid follicles called Peyer’s patches found in submucosa often extending in lamina propria
2.75m
cells of small intestine
enterocytes goblet cells paneth cells enteroendocrine stem cells
enterocytes
most numerous
tall columnar cells
brush border
absorptive cell
goblet cell
produce mucin to protect epithelium
lubricates passage of material
paneth cells
base of crypts of Lieberkuhn
defensive function
regulates bacterial flora - secrete lysozyme and definsins
enteroendocrine (neuroendocrine) cells
produce hormones contributing to control of secretion and motility
e.g. gastrin, cholecystokinin, vasoactive intestine peptide
stem cells
base of crypts of Lieberkuhn
divide to replenish epithelium
large intestinal epithelium
absorptive cells - removal of salts and water
goblet cells - secretion of mucus to lubricate the colon
arranged into straight, tubular glands that extend down to muscularis mucosae –> crypts
teniae of large intestine
outer, longitudinal smooth muscle is distinct
not continuous but found in 3 muscular strips –> teniae coli
appendix
blind-ending hollow extension of the cecum.
structure is similar to the rest of the colon, but crypts are far less abundant and there is circular arrangement of lymphoid tissue in the submucosa and often the lamina propria.
lymphoid tissue declines with age.
rectoanal junction
distinct junction between mucosa of the rectum and the non-keratinized stratified squamous epithelium of anal canal
2-3cm long anal canal is continuous with the keratinized stratified squamous epithelium of the surrounding skin.
plexuses of enteric nervous system
2 plexuses;
one in the submucosa - submucosal) - controls muscle of muscularis mucosae and regulates secretion in epithelium
one between the muscle layers of the muscularis externa - myenteric - controls gut motility
what is a ganglion
Most neurones live in groups
a group of neurones living outside of the brain and spinal cord is called a ganglion
