Pancreas/Gall Bladder Physiology Flashcards
What cells in the pancreas secrete digestive enzymes?
Acinar cells
What cells in the pancreas secrete bicarbonate?
Centroacinar and duct cells
What proteases are secreted by the pancreas?
Trypsinogen
Chymotrypsinogen
Proelastase
Procarboxypeptidase A and B
What amylolytic enzymes are secreted by the pancreas?
Amylase (pancreatic amylase)
What lipase are secreted by the pancreas?
lipase
Nonspecific esterase
Prophospholipase A2
What nucleases are secreted by the pancreas?
Deoxyribonuclease
Ribonuclease
What is the role of colipase?
Works with lipase to activate it.
What are the granules called that hold enzymes in the pancreas?
Zymogen granules
What two ions are exchanged as a part of the duct function?
Bicarbonate pushed out for chloride being brought in
What transporter is important for Cl homeostasis in the centroacinar cells?
CFTR
During the cephalic/gastric phase, what stimulates acinar cells?
ACh, GRP from vagal centers
In the intestinal phase, what changes in enzyme output is seen?
30% enzyme output increased to 70%
What cells secrete CCK? What activates them?
I cells activated by CCK-RP and monitor peptide
What cells secrete secretin? What activates them?
S cells activated by H+
What is the intracellular pathway by which acinar cells increase content discharge?
Ca mostly
Then cAMP
What activates CCK-RP release?
Amino acids and fatty acids in lumen
What are four things that CCK does?
Gall bladder contraction
Pancreas acinar secretion
Stomach reduced emptying
Sphincter of Oddi relaxation
What activates trypsinogen?
Enteropeptidase
What enzyme is mutated in hereditary pancreatitis? What is its role?
PRSS1 gene
Trypsinogen gene mutation that prevents trypsin elimination
What are some effects of pancreatitis?
Abdominal pain from pancreatic autodigestion
Increased serum lipase and amylase
Steatorrhea and fat-soluble vitamin insufficiency
Malignancy, diabetes, infx
Why does oral glucose lead to higher insulin levels than IV glucose?
GLP1 is released from L cells in the intestine and GIP from K cells
What happens to satiety when someone lacks sleep?
Leptin levels lower, decreasing satiety and inducing hyperphagia and overeating
What four hormones stimulate insulin secretion of beta cells in the islets of langerhans? Which are negative regulators?
GLP-1, gastrin, cholecystokinin, and acetylcholine
Negative regulators: somatostatin, norepinephrine
What molecules are satiety signals at the hypothalamus?
GLP1, CCK, Insulin, Leptin
What molecule stimulates appetite and decreases energy expenditure?
Ghrelin
What produces ghrelin?
Fundus of stomach
What are the major functions of the liver?
Processing all ingested nutrients, detoxification
Metabolism of carbs, fats, proteins
Buffers glucose
Synth of factors important for circulatory system
Bile formation for uptake and excretion of lipophilic molecules
What cells synthesize bile?
Hepatocytes
What is the hepatic triad?
Portal vein, hepatic artery, bile duct
What is a Kupffer cell?
Macrophage of the liver
Where are chylomicron remnants sieved into?
Space of Disse
What is the role of stellate cells?
Produce collagen
Store lipids like Vitamin A
What synthetic cells are hyperactive in cirrhosis?
What does that cause?
Stellate cells
Irreversible deposition of excess collagen
What causes stellate cells to be hyperactive in cirrhosis?
Oxidative stress causes Kupffer cells to release cytokines inducing collagen production
What is hepatic encephalopathy?
When toxins enter blood stream because of too much shunting
What facilitates excretion of hydrophobic molecules?
Bile salts
Describe the pathway of bile salts
Secreted into bile duct Concentrated in gall bladder Passes to duodenum Reabsorbed from ileum into portal vein Goes back to liver
How much of the bile salts are lost in feces?
5%
What enzyme is critical for cholesterol conversion into bile acid?
7-a-hydroxylase
What must be added to a bile acid to become a bile salt?
Glycine or taurine
What bacterial product of bile salts must be sulfated and excreted?
Lithocholic acid
After leaving the canaliculi, where does bile go? What lines these ducts?
Canals of Hering
Lined with cholangiocytes
What is taken out and added in the canals of Hering
Glucose and amino acids removed
IgA and mucus added
What causes bile to be concentrated in the gall bladder?
Na and Cl pumped out of bile, water follows osmotic gradient
What transporter is responsible for conjugated bile salt uptake from the GI lumen? Where is it found?
Apical sodium-dependent bile salt transporter
Foundin Ileum
What transporter is responsible for taking up conjugated bile salts from the sinusoids?
Na dependent taurocholate transporter
What are causes of cholestasis (impaired bile secretion)?
Primary Biliary Cirrhosis (destruction of cholangiocytes)
Primary Sclerosing Cholangitis (inflammation of bile ducts)
Pregnancy (progesterone reduces GB smooth muscle tone)
What are some effects of cholestasis?
Metabolic dysfunction (bile accumulation in liver)
Itching (bile in plasma)
Hypercholesterolemia
Deficiency of ADEK
