small inestine Flashcards
what is it made up of
duodenum
jejunum
ileum
how is the surface area increased
mucosal folds called villi
how is the surface area on villi increased
microvilli
what does villus core contain
- blood vessels
- lacteals
- cells
what are the spaces between the villi called
crypts of Lieberkuhn
where are enterocytes formed
at the bottom of the crypts
where do enterocytes migrate to
tops of the villi
what is the blood supply to the small intestine via
branches of the superior mesenteric artery
what are the terminal branches
end arteries
are there anastomoses in small intestine
no
what does the enteric nervous system coordinate
- absorption
- secretion
- blood flow
- motility
what are the 2 plexus of the enteric nervous system
myenteric
submucosal
how does the enteric nervous system communicate with the central nervous system
via the autonomic afferent and efferent pathways
where do interstitial cells of cajal lie within
smooth muscle
when does migrating motor complex occur
during fasting
how many phases is the MMC
3
how long does MMC cycle last
90 minutes
what is MMC like after a meal
irregular lasts for 2-5 hours
what cells secrete CCK
I cells
what does CCK cause
gall bladder contraction and sphincter of oddi relaxation
what cells secrete gastrin
G cells
what does gastrin stimulate
acid secretion
what cells secrete secretin
S cells
what does secretion stimulate
pancreatic bicarbonate secretion
what releases glucagon
alpha cells
what does glucagon do
opposes insulin in blood glucose control
what cells secrete VIP
enteric nerves
what cells secrete GIP
K cells
what does GIP cause
greater insulin release by islets
what cells release glucagon-like peptide-1
L cells
what does GLP1 cause
insulin synthesis
inhibits glucagon secretion and gastric emptying
what cells release pancreatic polypeptide
PP cells
what does pancreatic polypeptide cause
inhibits pancreatic and biliary secretions
what cells secrete peptide YY
L cells
what does peptide YY do
inhibit pancreatic exocrine secretion
reduces food intake and appetite
what does motilin do
increase gastric emptying and small bowel contraction
what does ghrelin do
stimulate appetite, increase gastric emptying
what does obestatin do
opposes ghrelin
what does oxyntomodulin do
inhibit appetite
what cells secrete somatostatin
D cells
what does somatostatin do
inhibit secretion and action of most hormones