Lecture 5 Flashcards
What secretes cholecystokinin and in response to what
Acinar cells in the duodenum
In response to fatty foods and aa
What is a major stimulus for gallbladder contraction
CCK
CCK is a major stimulus for what
Gall bladder contraction
What 3 things does CCK do
Stimulates gallbladder contraction
Stimulates secretion of pancreatic juice
Relaxes hepatopancreatic sphincter
Bile salts are recycled through what
Enterohepatic circulation
Most bile salts are reabsorbed by what section of the GI tract
Ileum
Reabsorbed bile salts travel via what vein back to the liver
Hepatic portal vein
What is the most important stimulus for bile secretion
Bile salts in portal circulation
What triggers the release of CCK
Protein and fats in chyme entering the duodenum
during cephalic and gastric phases _____ nerve causes weak gallbladder contractions
Vagal nerve
When the gallbladder is removed, how does the body compensate?
It enlarges the bile duct to allow more bile to be stored
What is obstructive jaundice
liver cannot eliminate the bile, as gallstones block the pancreatic duct
What are acini
groups of secretory acinar cells clustered around ducts
What do acini mediate
Exocrine function of the pancreas
What does an acinar DUCT cell secrete
bicarbonate and water
Is pancreatic juice alkaine or acidic
Alkaline
How much pancreatic juice do we produce a day
1200-1500ml
What two things does the alkalinity of pancreatic juice allow it to do
Neutralize acidic chyme
Create optimal pH for intestinal and pancreatic enzymes
Why are proteolytic enzymes released in “inactive precursor form”
to prevent unwanted protein degredation;
make sure they activate in the proper place
What do amylase, lipases and nucleases typically require to function optimally
Bile or ions
What is the alkaline tide
Bicarbonate production in the stomach
What is released into the bloodstream from the pancreas that neutralizes the bicarb secreted into the blood from the stomach
H+ ions
What are the two main intestinal hormones
Secretin and CCK
What controls the vagal stimulation of secretory activity in the pancreas
Parasympathetic nervous system
What do duodenal enteroendocrine cells secrete in the pancreas
CCK and Secretin
What is the full name of CCK
Cholecystokinin
What triggers the release of secretin
Acidic chyme
How does the small intestine absorb
Through absorptive cells through apical brush border
How much intestinal juice is secreted a day
1-2 L
what is a major stimulus for secretion of intestinal juice
Distension or irritation of intestinal mucosa
Are the contents of the stomach hypo or hyper tonic?
Hypertonic
What is segmentation
The way the SI churns, squeezing the lumen in different spots to compartmentalize
What is segmentation initiated by
Intrinsic pacemaker cells
Whats the frequency of segmentation in the duodenum
12-14/ min
Whats the frequency of segmentation in the ileum
8-9/min
How long is the MMC
90 mins
What is the MMC
Migrating mobility complex
Repeated peristaltic action
Chemical reaction for digestion of complex molecules involves _____
Hydrolysis
What is a monomer
Monosaccharides
Where are monosaccharides absorbed
Directly in the SI
What are three major dietary monosaccharides
Glucose
Fructose
Galactose
Glucose, fructose and galactose are ____ because they have the same composition
Isomers
Sucrose is composed of
Glucose and Fructose
Lactose is composed of
Galactose and glucose
Maltose is composed of
Two glucose
Glycogen and starch are:
Polysaccharides
What is the common storage form for carbs in muscle and liver
Glycogen
Why is glycogen a good storage form?
We have enzymes that will break it down very easily
What is cellulose
plant polysaccharide
Cellulose cannot be digested, but why is it important
It provides fiber
Can cellulose be digested?
Nope
What starts the digestion of carbohydrates
Salivary amylase
What is carbs reduced to in the mouth
Oligosaccharides
What is an oligosaccharides
3-8 monomers
What digests salivary amylase
Pepsin
What reduces most starch to maltose and where
Pancreatic amylase and in the SI
What completes carb digestion to monosaccharides
Intestinal brush border enzymes
