digestive system small intestine Flashcards
how does the Si produce intestinal hormones?
using DNES cells
what 3 surface adaptations increase surface area of Si?
plicae circulares
villi
microvilli
what is another name for plicae circulares?
valves of Kerckring
what are the permanent folds affecting the mucosa and submucosa found throughout the duodenum, jejunum and proximal ileum?
plicae circulares
where are the microvilli of the small intestine located?
on the luminal cell surface
what is the surface epithelium of the small intestine (Si)
simple columnar
what are the 6 cell types of the Si?
surface absorptive cells- enterocytes goblet cells DNES cells regenerative cells paneth cells M (microfold) cells
which cell type absorbs water and nutrients and has terminal digestion in the glycocalyx?
surface absorptive/ enterocytes
where are goblet cells of Si concentrated?
fewest in duodenum and most in ileum
how many types of DNES cells do we have in the Si?
11 types
which type of DNES cell stimulates CCK?
type I
what hormone stimulates gallbladder contraction and pancreatic secretion of enzymes from serous acini?
CCK
which type of DNES cell produces GIP and inhibits HCL release?
type K
which DNES type produces secretin?
type S
what hormone stimulates pancreatic secretion of bicarbonate from the pancreatic ducts and also inhibits HCL release and movement of chyme into Si?
secretin
where are regenerative cells found and how long do they live?
found in crypts and live 5-7 days
how long do paneth cells live?
20 days
where are paneth cells located?
base of the crypts (intestinal glands)
what is the fx of the paneth cells?
produce lysozyme
what cells are located at the ileum epithelium over Peyer’s patches?
M (microfold) cells
what cells contain large intracellular pockets that are fairly open to the lamina propria?
M (microfold) cells
what is the function of the M cells?
promote humoral immunity
- causes plasma cells to produce IgA which is then transferred to epithelial cells and released into gut lumen
- important for maintaining gut flora
what is the lamina propria of the Si made of?
loose areolar CT
if the longitudinal muscle of villus core is irritated then the muscle contracts and the villi shorten. What can this lead to long term?
nutrient deficiencies
what does the LP of Si border?
intestinal glands
what are lacteals?
lymphocyte capillaries
what is the fx of lacteals?
most lipid absorption
what structures are found in villus core of LP?
lacteals
vascular components- smaller vessels
longitudinal muscle
what are the 3 important characteristics of the lamina propria of the Si?
found in villus core
borders intestinal glands
has muscularis mucosae
what is another name for intestinal glands?
crypts of lieberkuhn
what is the muscularis mucosae of the LP of Si like?
thin but present; connects to smooth muscle in villi
what cell type replaces other cells?
regenerative cells
which cells are surface absorptive cells?
enterocytes
which cells promote humoral immunity?
M cells
which cells produce lysozymes?
paneth cells
does secretin of CCK inhibit stomach activity?
secretin
what stimulates the gall bladder?
CCK
what stimulates the pancreas to release digestive enzymes?
CCK
what stimulates ducts in pancreas to release bicarbonate?
secretin
what are lacteals?
lymphatic capillaries
where are paneth cells found and what do they do?
base of crypts, produce lysozyme
where are Brunner’s glands found? what do they do?
found in submucosa of duodenum; secrete alkaline mucus to neutralize chyme
what is the submucosa of the Si made of?
very dense CT with larger blood vessels
what are the duodenal (brunner) glands?
seromucous glands
what 2 products do Brunner glands produce?
alkaline mucus
urogastrone
what does urogastrone do?
inhibit HCL secretion and increase mitosis of epi. cells
what are the 3 structures of the submucosa of the Si?
duodenum
jejunum
ileum
where are the Peyer’s patches located?
ileum
what are Peyer’s patches?
group of regularly occurring large lymph nodules
the submucosal (meissner’s) plexus of ileum has what type of innervation?
parasympathetic
what is the fx of the submucosal/meissners plexus?
influence mucosa
what is the pattern of the muscularis externa of the Si?
normal- inner circular, outer longitudinal
what structure stimulates the muscularis externa for peristalsis?
myenteric (auerbach) plexus of Si
what part of Si is serosa?
all of jejunum and ileum, 1st and last 1-2 cm of duodenum
what part of Si is adventitia?
vertical/descending portion of duodenum
what is the only digestive organ with both serosa and adventitia?
small intestine
where is the ileocecal valve found?
btw ileum and cecum of colon
what is the structure of the right side that extends from the cecum?
veniform appendix
what is the surface epithelium of the appendix?
simple columnar
