Histology Flashcards
What is the oral cavity, oropharynx and laryngopharynx lined with?
generally non keratinised stratified squamous epithelium
what is the nasal cavity and nasopharynx lined with?
respiratory epithelium
What type of cells is the tongue made of?
anterior 2/3 - stratified squamous epithelium, thin on ventral surface, thick and with papillae on the dorsal surface
posterior 1/3 - covered by smooth stratified squamous epithelium which, except for the circumvallate papillae, lacks papillae but does have substantial lymphoid aggregates in the submucosa
What is included in the pharynx?
ring of lymphoid tissue composed of the palatine tonsils, lingual tonsils, tubal tonsils and pharyngeal tonsils (adenoids)
What are 4 major layers in the digestive tract called?
- mucosa
- submucosa
- muscularis externa
- serosa or adventitia
what are the three parts of the mucosa called?
epithelium - sits on a a basal lamina
lamina propria - loose connective tissue
muscularis mucosae - thin layer of smooth muscle
what is the submucosa made of?
loose connective tissue
what is the muscularis externa made of?
two thick layers of smooth muscle, an inner circular layer and an outer longitudinal layer
what is the serosa or adventitia?
outer layer of connective tissue that either suspends the digestive tract or attaches it to other organs
Where are glands in the submucosa found?
oesophagus
what does the surface of the stomach look like?
flat surface but with holes in it - called gastric pits
what is found at the bottom of gastric pits?
1-7 gastric glands
what are gastric pits lined by?
surface mucous cells
what is the isthmus mostly made of?
mostly parietal cells and stem cells
what is the neck of gastric glands made of?
neck mucous cells and parietal cells
what is the fundus (base) of the gastric glands made of?
chief cells with a few parietal cells and enteroendocrine cells (also called neuroendocrine cells)
what do parietal cells do?
produce hydrochloric acid
what do chief cells?
digestive enzyme secreting cell
what is unusual about the muscularis externa of the stomach?
has an additional layer, this layer is oblique and located internal to the circular layer. this layer aids the churning action of the stomach
what is the most common type of cell in the small intestinal epithelium?
enterocytes
what cells are there in the small intestinal epithelium?
enterocytes, goblet cells, paneth cells, enteroendocrine cells and stem cells
what is the acidic, partly digested semifluid material the duodenium recieves from the stomach called?
chyme
what other region apart from the oesophagus has glands in the submucosa?
duodenum
what are the glands in the duodenum called? what do they do?
brunner’s glands - when stimulated by the presence of chyme they produce a thin, alkaline mucous to neutralise the chyme
what are peyer’s patches?
areas of relatively large aggregations of lymphoid tissue
what are the two types of cells in the large intestinal epithelium?
absorption cells and goblet cells
what do goblet cells in the large intestinal epithelium do?
secrete mucus to lubricate the colon
what are the 3 muscular strips of the large intestine called?
teniae coli
what is the digestive tract nervous system called?
enteric nervous system
what is the interconnected network of fibres that controls gut motility called?
myenteric plexus
what is a group of neurons living outside the brain or spinal cord called?
ganglion (plural is ganglia)
what is the network of neurons which controls the muscle of the muscularis mucosae and helps regulate secretion called?
submucosal plexus
how do the liver and pancreas develop?
outgrowth from the gut
what is the parenchyma of the liver and pancreas composed of?
glandular epithelial cells
what is the liver capsule made of?
collagenous connective tissue, which is covered by a layer of mesothelial cells derived from the peritoneum.
what are the segments of the liver called?
lobules
what does each lobule of the liver have?
a branch of the hepatic vein called the centrolobular vein (or central vein) at its centre and portal triads at each corner
what are portal triads?
points of blood entry
what do portal tracts/triads include branches of?
hepatic portal vein
hepatic artery
bile ductule
what is the bile ductule lined by?
simple cuboidal cells called cholangiocytes
what are the main cells of the liver?
hepatocytes
what are the blood channels in the liver called?
sinusoids
what are sinusoids lined with?
endothelial cells
what is the narrow space between the lining cells of the sinusoids and the hepatocytes called?
space of Disse (or the perisinusoidal space)
what is the parenchyma of the liver supported by?
reticular fibres, type III collagen as well with some type I collagen
what are the cells found scattered in the space of disse called?
hepatic stallate cells
what are hepatic stallate cells?
modified fibroblasts and make connective tissue. store vitamin A within fat droplets in their cytoplasm.
what can happen to hepatic stallate cells in some pathological conditions?
they can transform into myofibroblasts and produce scar tissue in the liver
what type of cells are scattered in the sinusoids?
resident macrophages called kupffer cells.
what do kupffer cells do?
remove particulate matter from the blood and help remove worn out red blood cells
What is bile?
alkaline solution containing water, ions, phospholipids, bilirubin and bile salts.
what is bilirubin?
pigment which results from the breakdown of haemoglobin in the spleen, it is the principle cause of the brown colour of feaces.
what are bile salts important for?
emulsification of fats in the digestive system
which cells produce bile?
hepatocytes
what does bile flow via?
bile canaliculi
what is the bile canaliculi?
small channels formed by tight junctions in the cell membranes of adjacent hepatocytes.
what is the gall bladder made of?
it is a muscular sac lined by simple columnar epithelium backed by a lamina propria of loose connective tissue rich in blood vessels and lymphatic vesselsm a coat of smooth muscle and an outer collagenous layer of adventitia.
what does the gall bladder do?
stores bile and modifies it.
what is the name of the hormone which stimulates the gall bladder to contract and deliver bile to the duodenum?
cholecystokinin
what is the inflammation of the gall bladder called?
cholecystitis
what are the small scattered islands of tissue in the endocrine pancreas called?
islets of langerhans
what are the islets of langerhans do?
produce hormones such as insulin and glucagon.
why does the pancreas not digest itself?
the enzymes are proenzymes until they arrive at the duodenum.
what happens when the pancreatic secretions reach the duodenum?
an enteropeptidase converts the inactive proteolytic enzyme trypsinogen into the active form, trypsin. this begins a cascade that results in the activation of other enzymes.
what are the ducts in the pancreas called?
centroacinar cells
what is the hepatopancreatic ampulla (of vater)?
the main pancreatic duct joins the common bile duct and opens into the duodenum a papillae
