small intestine and pancreas Flashcards
What are the small intestine known for?
brk dwn food (chyme) and absorption
Chyme is made up of?
Stomach acid, enzyme and food mixture
Entrance of the small intestines?
pyloric sphincter
3 sections of the small intestines
Duodenum -closest to stomach -Brunners glands in submucosa :produce mucous for protecting small intestine wall from chyme (has acid) :incre.=closer to pyloric sphincter in stomach Jejunum Ileum -exit sm. -->lrg intestine
Where is plicae circularis located?
small intestine
Plicae circularis info.
Incre. SA w/o incre. length=folding Has the highest degree of folding Degree types of folding -1st=Plicae itself (structure) :evagination of submucosa w/ mucosa layer of covering -2nd=Villus :Evagination of mucosa only -3rd=cyrpts of liberkuhn :glands and mucosa invagination -4th=microvilli :apical of enterocyte evagination
Are there diff. types of villus w/in the sm. intestine
Yes
Duodenum=Leaflike shape broad/not too long
Jejunum=Finger-like long/skinner
Ileum=Shorter villi and still skin
Villus-mucosa
Smp. columnar epith.
Enterocyte w/ microvilli
-spec. cell type allowing absorb food macromolec.
Villus=projection of LP containing lacteals
-lacteals are blind lymph vessle/collapse during preparation
Enterocytes
Primary function=absorp.
Tall columnar cells w/ microvilli to incre. SA
Release enzyme to brk dwn disacch. and peptide
-dnt brk dwn prot. brkdwn product of prot. brkdwn
Produce lipases and bile acids
-bile acids=produce by bile emulsify lipids for lipase access
Enterocytes and junctional complexes regulate movment of H2O across epith.
Help keep H2O influx
-inject. diarrhea=damage junction casuing watery diarrhea
Enterocyte and microvilli
Incre. SA w/ actin core
Apical cell portion connect to terminal web
-supports barrier cell function by connecting to IF and cell-cell junction
After prot. brkdwn to peptide/AA by symporter
Brkdwn carb. to monosacch.=specific uptake
Brkdwn lipid FA=cross memb. w/ transprot prot.
Small intestine-LP
Loose CT -Fibroblast -Plasma cells -eosinophils(nt resident but still found there) -mast cells -MAC Surrounds crypts of lieberkuhn Small BV -support function/take up nut.
Difference b/w villus and crupt of lieberkuhn
Growth
-villus=above surface
-crypts=below surface
Enterocyte w/ goblets=both
Paneth cells=crypt only
-Exocrine cells secrete to crypt lumen and has apical secreting granules
-protective enzymes
:lysozyme=attack bact. cell wall
:phospholipase A2=attack bact. cell memb.
:defins r peptide=bind/brkdwn memb. and cell wall of micro-organism
Enteroendocrine=crypt only
-endocrine secrete into tissue @times not have granules
-nuclei r gen centered
-clear cytoplasm w/ basal granules
Submucosa-Duodenum
Dense CT
Has bruners gland=mucous to protect lining from chyme
Submucosa-Jejunum
Dense CT
Submucosa-Ileum
Dense CT Payers patches -M cell assoc. w/ enterocyte -lymph vessels under -cells w/o microvilli and smp. cuboidal
Muscularis externa-small GIT
2 layers of sm. muscle=inner circ. and outter long.
-segmentation=2 sides will contract while middle relax
:helps w/ mixing food
-Peristalis=1 area contract as dwn strm relax to push dwn the anus
2 N. plexus=meisners(submucosa) and myentric plexu (b/w 2 muscle layers)
-apart of the intrinsic enteric N. controling motor/sensory acivities in digestive tract
Adventia and serosa-small GIT
Both of dense CT
Smp. sq. epith. (mesothelium)=only serosa
Adipose/lrg BV and N= adventitia
2 types of glands in pancreas
Endocrine and exocrine
Pancreas-endocrine
Action=secrete metobolic horm.
Highly vasculized=Y to support Nut. in and waste out
Location=w/in pancreatic iselt(islet of langerhon)
-3 cells that cn be distinguish by HE (only seen in IF)
:alpha=glucagon to incre. blood gluc.
:beta=insulin to decre. blood gluc.
:delta=somatostatin and gastin
-inhib. alpha and beta
-affect parietal cell to produce HCl and pit. gland
Which pancreatic endocrine cells controlled by blood gluc. ?
alpha and beta
Pancreas-exocrine
Action=produce digestive enzyme into duodenum
Highly vasc.=NO
Location=around pancreatic islet
deeper exocrine explanation
Secretory enzyme/granules=pancreatic acinar cells
-acinar cell
:acini shape of gland w/
Contain granule=lipid-based vesicles filled w/ zymogen
-pro digestive enzyme
Release productive apical into interlobular duct (lined centroacinar cells) –>intralobular duct
-controlled by CCK=secretin (not control by granule)
Pancreas-exocrine ducts
Centroacinar cell start to line first Intercalated duct line w/ sq. epith. -connected to intralob.-->main duct-->dudodenum -nt striated -most of the 1L fluid/day secretion :a little fluid from acinus -most ion :rich in Na and Bicarb(correct pH for enzymes from chyme) -Nutrilze chyme
pancreatic enzymes
Bicarb.=not by acinar cells Porteases=chymo, trypsin, elastase, protease E, Kallikrein Alpha amylase-brk dwn carb. Lipases DNases and RNases
Trypsins
activated in small intestine and cleave other zymogens to activate them
pancreatic enzyme travel
Main pancreatic duct (of wrsung) Hepatopancreatic ampulla (of vater) -w/ bile duct Major duodenal papilla Spincter of hepatopancreatic ampulla (of oddi)
