Histology of the gut Flashcards
organs of the alimentary canal
mouth
pharynx
oesophagus
stomach
small intestine
large intestine
accessory digestive organs
teeth
tongue
salivary glands
liver
gall bladder
pancreas
three functional compartments
oral cavity
simple passages
digestive tract
auxiliary gland system
secretory organs
oral cavity
ingestion and fragmentation of food
simple passages
transport of food or its residues without significant modification
oesophagus and anus
digestive tract
secretes enzymes induced in breakdown of food
absorbs molecules produced
stomach, small and large bowel
pharynx function
pharyngeal muscles propel food into oesophagus
oral cavity teeth and tongue function
mechanical breakdown, mixing with salivary secretions
liver function
secretion of bile (lipid digestion), nutrient storage, producing cellular fuels, plasma proteins, clotting factors and detoxification and phagocytosis
oesophagus function
carries food and liquid from your throat to your stomach
stomach function
Digestion
gall bladder function
Stores bile
large intestine function
absorb water and salts from the material that has not been digested as food, and get rid of any waste products left over
small intestine function
helps to further digest food coming from the stomach
label the epithelial top to bottom
stratified squamous
simple columnar x 4
stratified cuboidal
stratified squamous
stratified squamous (keratinised)
four layers of the gut label A-D
mucosa
submucosa
muscular externa
adventitia
sublayers of the mucosa layer and their functions
epithelium: mucous production and protection
lamina propria: capillary rich absorption, MALT
muscular mucosa: localised movements
functions of the submucosa layer
highly vascularised: enhances nutrient absorption
assists the passage of bolus (mucous glands are present)
contains submucosal (meissner) nerve plexus: controls muscle cells and glandular secretions
function of the muscularis externa
outer longitudinal and inner circular layer (smooth muscles)
function is for peristaltic activity: contractions of the muscular are generated and coordinated by the myenteric plexus
adventitia layer
made of loose connective tissue
this layer after it crosses the diaphragm is called serosa (for intraperitoneal)
what type of epithelium lines the oesophagus
stratified squamous non-keritinized epithelium
what type of cell may be found within the mucosa lining the lumen of the oesophagus
langerhans cells (antigen presenting cells)
function of langerhans cells
phagocytose and degrade antigens
what is Barret’s oesophagus
untreated GERD causes metaplastic changes in the lining of the oesophagus (usually in the lowest region)
if left untreated can lead to cancer
label the regions of the stomach top to bottom
oesophagus
cardia
fundus
body
pylorus
pyloric sphincter
duodenum
label the muscularis externa in the stomach
longitudinal
circular
oblique
label the gastric gland
pit
isthmus
neck
base
cells found on the top of the gastric gland
surface lining cell
regenerative cell
cells found on the neck of the gastric gland
mucous neck cell
oxyntic (parietal) cell
cells found on the base of the gastric gland
zymogenic (chief)
enteroendocrine
function of surface lining cells in the gastric gland q
cover the luminal surface of the stomach
partly line the gastric pits
packed with cytoplasmic mucigen granules that are poorly stained by H&E
short surface microvilli and secrete protective bicarbonate ions into deeper layers of surface mucous coat
function of pit in gastric gland
to secrete hydrochloric acid
function of the regenerative cell in the gastric gland
enables efficient stomach epithelium repair
function of the oxyntic or parietal cells in the gastric gland
secrete gastric acid
aids in digestion
function of the zymogenic cells in the gastric gland
production of pepsin and rennin
enzymes
function of the enteroendocrine cells in the gastric gland
hormone secretion
label the oesophagus
epithelium
lamina propria
muscular mucosa
submucosa
inner circular
outer longitudinal;
label A-E of the small intestine mucosa
intestinal lumen
villi
simple columnar epithelium
lamina propria
goblet cells (secrete mucous)
what are intestinal glands
crypts of Lieberkuhn
simple tubular glands
begin at the bases of the villi in the mucosa and extend through the lamina propria to the muscularis mucosae
what do the intestinal glands possess
absorptive cells
goblet cells
paneth cells
enteroendocrine cells
paneth cells
possess large, eosinophilic granules whose contents (lysozyme) digest bacterial cell walls
label this image of the duodenum
M - mucosa
V- villus
MM- muscularis mucosae
SM- submucosa
B- Brunner’s glands
CM- circular muscles
LM- longitudinal muscle
defining factor of small intestine
paneth cells
what is a classical feature of duodenum
Brunner’s glands
appear pale, therefore release mucus and help with lubrication
what is a classical feature of the ileum
Peyers patches (lymphoid aggregated nodules)
appear darker on a stain
label the image of the ileum
a- goblet cells: secrete mucus
b- structures found in the central core of villus microvasculature
also has other cell types such as fibroblasts, smooth muscle fibres and plasma cells
PEYERS PATCHES
what is this
duodenum
what is this
jejunum
what is this
ileum
large intestine
has simple columnar epithelium
main function is to absorb water, convert fecal matter form liquid to solid
similar histological features to the small intestine but has no villi and only has few paneth cells, abundant goblet cells
what is this image
appendix
MALT
mucosa associated lymphoid tissue provides protection against invaders of the mucosal connective tissue
what is this image
the mucosa and the transition of the epithelium in the rectal-anal junction
what is the epithelium lining the rectum
simple columnar epithelium
