GI The Small Intestine, Exocrine Pancreas And Biliary System Flashcards
What are the three parts of the small intestine
Duo jej and ileum
What does the small intestine recieve
Chyme form stomach duodenal bulb
Panc juice form panc more distal part of duo
Bile form gall bladder
What does the small intestine sec
Intestinal juice
How is the surface area in the small intestine
Very well adapted
Circular folds
Villi
Microvilli
The small intestine secretes some peptide hormones which are? What kind of sec
Endocrine cells prod these Gastrin Cck Secretin Motilin Glucagon like insulinotropic peptide Glucagon like peptide 1 Ghrelin
What produces cck
Form I cells in duo and jej
Enterogastrones
What produces secretin
S cells
What cells prod motilin
M cells
What are the incretins prod from
K cells and L cells
What do gr cells prod
Ghrelin
What do all the peptide homones of the small intestine act on
GPCR’s
How much intestinal juice prod a day
Approx 2 litres
What is the other name for intestinal juice
Succus entericus
What promotes Succus entericus prod
Gastrin Cck Distension Secretin Parasymp nerve activity
What decrease Succus entericus prod
Symp nerve activity
What dos Succus entericus contain
Mucus - for protection and lubrication form goblet cells
Aq salt - for enzymatic digestion in crypt of Lieberman
No digestive enzymes
What so the movements of segmentation
Chopping moving backward and forward vigour is after a meal
Alternation contractiona nd rleaxations of circular muscles
Initiated by BER
Initiated also by chyme distension
What is segmentation of an empty ileum triggered by
Gastrin form the stomach
Gastroileal reflex
What is segmentation movement like in pace
3-5 hours slow as allow time for abs
What changes the segmentation strength
The symp and parasymp activity
What is the MMc
Migrating motor complex
Between 90-120 min
Strong peristaltic contraction clearing small intestine between meals
What inhibits the MMc
Vagal activty and feeding
What triggers MMc
Motilin
Surpressed by Gastrin and cck
What is the endocrine part of the panc
Insulin and glucagon sce to blood
What is the exocrine part of the pancreas
Digestive enzymes form the acinar cells
And ions in panc juice
What do pancreatic duct cells produce
Bicarbonate rich solution to duo
Neutralises acidic chyme
What does the bicarbonate rich solution do
Protect the mucosa, barriers erosion of acids
And provide optimum oh for enzymes
What do the pancreatic enzymes do
Can completely digest food in absence of all other enzymes
Where are the pancreatic hormones produced
In the acinar cells
Enzymes stored in zymogen granules
What are the 5 enzymes pancreatic
3 proteases
- trypsinogen
- chymotrypsinogen
- procarboxypeptidase a and b
Panc amylase
Panc lipase
The proteases are inactive and then activates to what forms
Trypsinogen –> trypsin
Chymotrypsinogen –> chymotrypsin
Procarboxypeptidase a and b –> carboxypeptidase a and b
How are the inactive proteases activated
By emterokinases form mucosal cells
What are the phases of control of panc sec
Cephalic - mediated by vs gal activity of acinar cells
Gastric - gastric distension evokes vagovagal reflex = parasymp stim of acinar and duct cells
Intestinal - acid = secretin in crease bicarbonate prod
Fat proetin = cck increase digestive enzymes
What does the biliary system compromise of
Liver, gall bladder, associated ducts
Approx how much bile produced a day
0.6-1.2 litres a day
What happens to bile between meals
Store and conc I gall bladder
What sholens to bile during a meal
Chyme in duo stim gall bladder contract via cck and bagel activty
Sphincter of oddi open via cck
Bile spurts to duo via cystic duct and common bile ducts
What is bile composition
Secretion of hepatocytes - liver cells
Secretion of bile duct cells - cholangiocytes
What happens in the bile ducts
The bile secretions mix
What does bile do
Participate in digestion and abs of fats
How much does the use secreted form the bile duct cells constituent the overla volume
25%
What is the bile duct cell composition
Similar to panc alkaline juice
Ions and bicarbonate rich
What happens to the bile duct cell sec between and during meals
Between - has ionic comp near plasma
During meal - flow rate increases in repsonse to secretin form duo s cells
When the flow rate of bile duct cells sec increases what happens to the product of secretion
Have more bicarbonate as the exchanger at the apical mem less time for Cl/bicarbonate exchange so more bicarbonate in sec
What does the neural environment the bile forms allow
Michelle production
Neutralisation of chyme
Ph adjustment for digestive enzyme optimum
Protection of mucosa
What do hepatocytes sec
Primary juice form canuliculli which fuse and form biliary du tules
What is hepatic bile composed of
Primary bile acids mainly chain and chenodeoxycholic acids Water and electrolytes Lipids and phospholipids Cholesterol Immunoglobulin Bilirubin
What does bilirubin do
Only constitutes the yellow pigment
What can an excess of cholesterol lead to
Bile acids and lecithin may precipitate into micorsrytals that aggregate to gall stones
What sit he system which makes use of the bile in the body again a nd again
Enterohepatic recycling
What’s is the rate of synthesis of bile salts dept upon
Hepatic portal blood conc of salts
Low conc Stim syn
High conc inhib syn
What does cck do for the secretin of bile
Causes gall bladder contraction and relaxation of sphincter of oddi
What does secretin do tot the bilesec
Causes aq alkaline bile sec
What does vagal activity do to the bile sec
Via release of ACh
Produces mild sec repsonse in cephalic phase of digestion
What does gastrindo do
Stim sec by parietal and chief cells
Enhance gastric motility
Stim illeocecal motility
What’s dos secretin do
Inhib gastric emptying
Inhib gastric sec
Stim sec panc duct cells
Stim sec of bile form liver
What does cck do
Inhib gastric empty Inhib gastric sec Stim digestive enzyme sec by panc acinar cells Causes gall bladder contraction Relax sphincter of oddi
What’s is the small intestine the major site for
Digestion and absorption
