Histology - Digestive Tract Flashcards
oral cavity, oropharynx and laryngopharynx
covered by stratified squamous epithelium
generally not keratinised
nasal cavity and nasopharynx
covered by respiratory epithelium
anterior tongue -2/3
stratified squamous epithelium
thin on ventral surface
thick and with papillae on the dorsal surface
posteror tongue - 1/3
covered by smooth stratified squamous epithelium
lacs papillae but does substantial lymphoid aggregates in the submucosa
except circumvallate
tongue - papillae
fungiform
circumvallate
foliate
filiform - no tastes buds (occupy most of dorsal surface)
entrance to oropharynx
pharynx includes a ring of lymphoid tissue composed of the palatine tonsils, lingual tonsils, Tuvalu tonsils and pharyngeal tonsils - adenoids
digestive tract - IMPORTANT
4 major layers
MUCOSA
epithelium, lamina propria, muscularis mucosae
SUBMUCOSA EXTERNA
MUSCULARIS EXTERNA
SEROSA or ADVENTITIA
variations in GI tract mucosa
mostly in mucosal layer
gastro-oesophageal junction
abrupt transition from stratified squamous epithelium to simple columnar epithelium
stomach
gastric pit and gastric glands
gastric pits
lined by surface mucous cells
produces a specialised type of mucous - protect against acid of the stomach
cells of the stomach epithelium
gastric glands not evenly distributed
isthmus - parietal cells and stem cells
neck - mucous cells and parietal cells
fundus (base) - chief cells, some parietal cells and neuroendocrine cells
chief cell
digestive enzyme secreting cell
parietal cell
hydrochloric acid producing cell
stomach regions
mucosa differs
CARDIA - deep gastric pits that branch into loosely packed, tortuous glands
BODY - shallow gastric pits with long straight gastric glands
PYLORUS - deep gastric pits with branched, coiled gastric glands at a hight density than in the cardia
muscularis external of the stomach
areas contains an additional layer
oblique to the usual circular and longitudinal muscle layers and is located interval to the circular layer
aids churning action
gastroduodenal junction
abrupt transition from stomach mucosa to duodenal mucosa
inner, circular layer of smooth muscle is markedly thicken to for the pyloric sphincter
small intestine
villi
between the bases of adjacent villi are pits ‘drilling’ downwards
crypts of lieberkuhn
duodenum
contains Brunner’s glands in the submucosa
jejunum
tallest villi, located on permanent circular folds of the mucosa and submucosa, the plicae circularis
lymphoid follicles infrequent
ileum
characterised by shorted villli and aggregations of lymphoid follicles called Peyer’s patches found in the submucosa and often extending into the lamina propria
cells of the small intestinal epithelium
enterocytes goblet cells panted cells enterocendocrine cells stem cells
cells of the small intestinal epithelium
enterocytes goblet cells panted cells enterocendocrine cells stem cells
cells of the large intestinal epithelium
absorptive cells
goblet cells
arranged in straight, tubular glands referred to as crypts that extend down to the muscularis mucosa
large intestine
outer, longitudinal smooth muscle is distinct
not continuous but to is found in 3 muscular strips called teniaie ells
ganglion
group of nerve cells living outside of the nervous system
