Flashcards in GI Histology Deck (103):
2 less known functions of GI:
Secretion and Protection
5 main functions of GI?
4 common structural features of GIT? and 2 'other' features
Which GIT structural layer is most diverse in cells?
What are the 3 layers within the GIT Mucosa?
How often are mucosal epithelium renewed? How?
every 5-6 days via local stem cells
Types of mucosal epithelium cells are usually?
What is contained in the lamina propria of GIT mucosa? 4 things.
small blood vessels
What is the muscularis mucosae do?
thin layer of muscle marks the mucosal layer boundary, used for mixing
What kind of cells are usually barrier and found in esophagus/anal canal?
What kind of cells are usually secretory in GIT? where predominantly?
stomach, gastric glands
large intestine: tubular glands
What kind of cells are usually absorptive? where?
small intestine. columnar epithelium
What's the purpose of the submucosa connective tissue?
strength and elasticity
describe the submucosa connective tissue
Can you see small ganglia in the submucosa usually?
Hard to see without special stains
Are there glands and immune cells, blood vessels in submucosa?
Which is stronger: muscularis externa? muscularis mucosae?
how many layers usually for muscularis externa?
what are the two layers of muscularis externa? what do they do?
inner circumferential (narrowing)
outer longitudinal (sqeezing)
what and where are the ganglia called within the muscularis externa?
myenteric ganglia found between inner and outer layer
What does GI serosa do? what kind of cells? why?
allows organ movement
is there adventitia along the entire GIT? where? purpose?
Nope. in parts of esophagus and rectum
CT to join with surrounding structures
ENS is part of which system?
autonomic nervous system
What does ENS regulate?
smooth muscle activity
What does myenteric ganglia regulate?
smooth muscle activity
What does submucous ganglia regulate?
What kind of nerves are found in the ENS ganglia?
swallowing reflex does what?
propulsion of bolus
what kind of epithelium in esophagus?
two muscle types in esophagus? where? how controlled?
Top: striated (voluntary)
Bottom: Smooth (involuntary)
What kind of change between esophagus and stomach?
abrupt functional change in epithelium: squamous to glands
describe the 3rd external muscle of the stomach:
oblique layer, varies
4 kinds of cells you can find in a gastric gland? What do they secrete?
Parietal cells (HCl)
Enteroendocrine (gastrin Hormone)
Small intestine absorbs ___% of digestion products?
Are there immune cells in the small intestine?
Name the surface area increasing structures of the small intestine:
What are the spaces between villi called? purpose?
crypt of Lieberkuhn
secrete fluid and mucus
Why have muscularis mucosae in the small intestine?
moves villi to improve mixing of contents
where does the lamina propria of the small intestine go?
CT extends into core of each villus
What is found in the lamina propria of the small intestine?
blood, lymph vessels
What are the clear cells seen on the villi?
What are Paneth cells for? where are they?
secrete antimicrobial peptides
found deep in glands
THE distinctive histological feature of the duodenum?
Describe Brunner's Glands, where and purpose?
release alkaline mucus to protect
How are the plica circulares and the villi in the duodenum?
low plica circulares
What are Peyer's patches? where are they found?
aggregates of lymphoid follicles
Describe the villi and amount of goblet cells in the ileum
lots of goblet cells
describe Muscularis externa in large intestine.
3 bundles called taeniae coli
3 regions of large intestine?
immune cells in large intestine?
area with most goblet cells in colon
Large intestine mucosa have villi?
describe glands of Large intestine mucosa, what kind of cells?
More goblet cells in large or small intestine?
Describe rectum to anal mucosa transitional zone.
glandular to squamous stratified
what is the largest solid gland in the body?
6 primary functions of liver
glucose regulation (glycogen)
lipid metabolism (cholesterol)
absorption of fats into bile
storage of iron/vitamins
liver is 80% what?
what are sinusoids?
specialized liver capillaries
what kind of CT in liver?
reticular fibres of Type 1 and III collagen
what do the following the hepatocyte do?
the rough ER/golgi
Rough: protein synthesis
Smooth: fat/steroid metabolism
how many nuclei and mitochondria in hepatocytes?
lifespan of a hepatocyte?
if liver has extensive damage, how is the regeneration?
not same lobular structure, more fibrous
can live regenerate from damage from alcohol/hepatitis?
if severe, then no
how are hepatocytes organized in the liver?
in lobules around blood vessels
what are the 2 blood supplies to the liver?
hepatic portal system:75%
what is the portal 'triad'. 4 things.
hepatic portal vein
what kind of cells are the bile duct epithelium made of? vs. arterial epithelium?
smooth muscle in the central veins of the liver?
what converge on the central vein in the liver? then where does it go?
sinusoids to hepatic vein > IVC
what give rise to sinusoids?
vein and artery
blood in sinusoids flow where in relation to the lobule?
towards the middle of lobule
what kind of blood is in sinusoids?
describe the sinusoids' size?
larger than normal capillaries
special features of sinusoids?
gaps between hepatocytes
what are kupfer cells?
macrophages on inner walls of sinusoids
what is the gap between endothelium and adjacent hepatocyte in sinusoids called?
space of Disse
what is the space of Disse for?
easier to transfer certain nutrients
3 models of hepatocyte organization. they are? what are each of their foci?
1. Classic centres around central vein. Focus: BLOOD flow
2. Portal. Veins in periphery. focus on BILE.
3. Acinar. Focus: physiological oxygenation.
what is the surfactant produced in the liver called?
where is bile synthesized from?
what are the bile collection channels called?
what is the direction of flow for bile?
outwards to be collected in bile duct within triad
focus of acinar lobule model?
physiological: O2 saturation/metabolic function
portal lobule model focus?
what lobule model focuses on blood flow?
classic lobule model
what does the gall bladder do to the bile?
remove water and salts to concentrate it
what controls release of bile into duodenum?
sphincter of Oddi
what does classic lobule model focus on?
Bile flow focus model of lobules called?
Portal lobule model
what lobule model focuses on physiological [O2] and metabolic function?
What hormone controls bile secretion?
CCK from fat stim
what kind of cells in gall bladder epithelium?
what is the exocrine function of the pancreas?
create proenzymes/bicarbonate to be released into duodenum
2 areas of pancreatic exocrine cells are? colours on H&E?
What does the basal and lumenal region of pancreatic exocrine cells each do?
basal: rough ER - protein synthesis
lumenal: zymogen granules
which part of the pancreatic exocrine cells faces inward towards the central duct?
what is a acini?
balls of cells with a central duct
what % of pancreas is endocrine?
1-2% of total pancreas volume
about how many islets of langerhans are in the pancreas?
around 1 million
what do islets of langerhans make?