GI 4 Flashcards
What is the flow of bile from the liver to the duodenum?
Bile duct -> common hepatic duct -> cystic duct -> common bile duct -> sphincter of Oddi -> duodenum
How much of the pancreas is exocrine?
90%
_____ cells of pancreas synthesize and secrete hydrolases for digestion
–Acinar cells
____ cells of pancreas secrete bicarbonate and water
Duct cells
____ cells of pancreas are involved in Luminal digestion of carbohydrate, protein, fat.
–Impaired function causes maldigestion and
malabsorption.
Acinar cells of pancreas
_____ cells of pancreas are involved in neutralizing gastric H+ :secretes HCO3- into duodenum up to 145 mEq/L
Duct cells of pancreas
Proteolytic enzymes synthesized, stored and secreted as _______
inactive precursors.
Why Doesn’t the Pancreas Digest Itself?
Proteolytic enzymes synthesized, stored and secreted as inactive precursors.
Where are the inactive precursors activated?
In intestinal lumen
____ is synthesized, stored, and secreted with the precursors to make sure the inactive precursors don’t get activated prematurely in pancreas
Trypsin inhibitor
_______:
Blocked bile ducts lead to enzyme overrun of trypsin inhibitors that lead to active enzymes in pancreas beginning to digest it
Acute pancreatitis
What are the 2 stimuli for acinar cell enzyme secretion?
- CCK
2. ACh/GRP (vagovagal reflex)
What are the 2 indirect paths of CCK production?
Monitor peptide and CCK-RP
______ is involved in the following:
- Gallbladder contraction
- Acinar secretion of pancreas
- Stimulates receptive relaxation, reduces emptying, and reduces HCl secretion of stomach
- Relaxes sphincter of Oddi
- Protein, carb, lipid absorption and digestion
- Matching of nutrient delivery to digestive and absorptive capacity
CCK
What are the Two Stimuli for Ductal Cell Secretion of H2O and HCO3-?
- *Secretin (Secretin receptor)
2. Ach (M3 receptor)
Secretin released when pH < ____
4.5.
_____ is released when pH < 4.5.
Secretin
Below pH = ___, secretin release is maximal in segment of duodenum. Further release of secretin depends upon area of small intestine affected.
3,
What 2 phases are mediated by vagovagal reflex - low volume, high enzyme secretion (Ach/GRP)?
Cephalic and Gastric
At Low secretion rates of pancreatic juice -
bicarbonate concentration is ____
chloride concentration is ____
low; high
At High secretion rates of pancreatic juice -bicarbonate concentration is ____
chloride concentration is ____
high; low
What 2 ions remain constant at all flow rates in pancreas?
Na and K
What is the tonicity of pancreatic juice?
Isotonic
The secretion rate of the pancreas is proportionate to what three things?
Secretin, Ach, and CCK
_____ is a disorder caused by a defective CFTR
CF
Abnormal sweat composition.
Decreased pulmonary and pancreatic secretion.
Mendelian autosomal recessive occurrence.
CF
Defective ____ seen in CF causes:
–Sweat Cl- reabsorption;
–Pancreatic duct cell function;
–Pulmonary mucus clearance.
CFTR
In _____ pancreatitis, –Trypsin activation causes pain, inflammation
Acute
In _____ pancreatitis, destroys acini
Chronic
What 2 things can cause duct obstruction?
Gallstones
Tumors
Consequences of ______ reflect decreased digestive enzyme production
Pancreatitis
Without pancreatic enzymes, what percentage of fat is not absorbed causing steatorrhea?
60%
Without pancreatic enzymes, what percentage of protein and carbs are not absorbed?
30-40%
_______ functions:
Cleansing and storage of blood
Metabolism of nutrients
Synthesis of proteins (coagulation factors, plasma proteins, angiotensinogen)
Metabolism of hormones, chemicals
Storage of energy, vitamins, iron
Excretion of lipid-soluble waste products
Marked capacity for cellular regeneration
Hepatic functions
What range of bile is secreted each day?
600-1000 mL
Liver has ____ blood flow and lymph flow
High
What percentage of CO is set to liver?
27%
Resistance of vessels in liver to blood flow is _____
Low
Cirrhosis increases resistance, produces _______: back up of blood in digestive tract; Increase NFP leading to ascites
portal hypertension
Hepatic lymph accounts for ____% of total body production.
50%
______ and _______ required for digestion(emulsification) and absorption(micelles) of dietary fat.
Bile salts (acids) and lecithin
Biles is involved in the _______ of lipophilic metabolites (bilirubin), excess cholesterol, other waste products, drugs, and toxins.
Excretion
Bile ____ are involved in emulsification of facts
Salts
Bile _____ are waste products
Bile pigments
_______ secrete bile salts, cholesterol, lecithin, bilirubin, many other lipophilic substances
Hepatocytes
_______ modify primary secretion, add HCO3
Duct epithelial cells
Storage and concentration of bile in ______.
gallbladder
________ reabsorbs some components.
Enterohepatic circulation
____ secrete organic component of bile into bile ducts-Bile Salts (produced from cholesterol)-Cholesterol-Organic substances
Hepatocytes
What are the 3 organic components that hepatocytes secrete into bile ducts?
Bile salts
Cholesterol
Organic substances
What are the 2 places bile is transported?
Small intestine for fat digestion
Gall Bladder for storage
What are the 3 things bile duct cells secrete?
Water
Na+
HCO3-
The gallbladder reabsorbs what 2 things?
Na and H2O
Does the gall bladder concentrate or dilute bile?
Concentrates bile
What is the max volume that can be stored in gall bladder?
30-60 mL
Substance secreted into bile by hepatocytes.
Delivered to lumen of ileum, then reabsorbed.
Transported to hepatocytes via sinusoids
94% of bile salts recirculated
Bile salts circulate 17x before lost in feces.
Enterohepatic circulation
What percentage of bile salts are recirculated?
94%
What is the the transporter involved in active absorption of bile salts in enterohepatic circulation?
Apical sodium-dependent bile salt transporter (ASBT)
Drugs that inhibit Bile Recycling
Used to lower LDL levels in blood
Hepatocyte production of bile increases 6-10x if bile salt recycling reduced.
LDL taken up from blood via hepatocytes as source of cholesterol for bile salts
Drugs work in intestinal lumen (do not need to be absorbed)
Reduce harmful side effects
BARI (Bile Acid Reabsorption Inhibitors)
____ is a type of BARI that Bind to bile salts in intestinal lumen and block transport
- Bile acid sequestrants
Low \_\_\_\_ is associated with the following things: Crohn’s disease Congenital 1° bile acid malabsorption Idiopathic chronic diarrhea Irritable Bowel Syndrome
ASBT
Low ASBT is associated with what 4 things?
Crohn’s disease
Congenital 1° bile acid malabsorption
Idiopathic chronic diarrhea
Irritable Bowel Syndrome
_____ dysfunction impairs bilirubin, bile salt secretion:
–Drugs (acetaminophen), viral hepatitis, toxins;
–Fibrosis, cirrhosis.
Hepatocyte
______ defects impair bile salt reabsorption.
Intestinal mucosal
(stomach)
amino acids and peptides
distention
(H+ inhibits)
Gastrin
______ (stomach)
absence of nutrients
(inhibited by stretch)
Ghrelin
______ (Small Intestine)
H
Secretin
___ (Small Intestine)
amino acids and peptides
fatty acids
Indirectly via secretion of CCK-RP and Monitor peptide
CCK
______ (Small intestine)
Glucose
GIP, GLP-1
_____ (Small Intestine)
stimulus unknown
some studies suggest that an alkaline pH in the duodenum stimulates its release.
Motilin
\_\_\_\_\_ ↑ Histamine Release (ECL cell) ↑ H+ Secretion (Parietal Cell) ↑ Gastric emptying Trophic affects on Mucosa
Gastrin
______
↑ Hunger
Ghrelin
______
↑ Gastric Motility (MMC/Fasting)
↑ Intestinal Motility (MMC/Fasting)
Motilin
_______
↑ Insulin response to glucose
↓ Gastric Acid Secretion
↓ Gastric emptying
GIP, GLP-1
\_\_\_\_\_\_\_\_ ↑ Panc & Biliary HCO3- secretion Trophic affects on Exo. Pancreas ↓ Gastric Acid Secretion ↓ Gastric emptying
Secretin
\_\_\_\_\_\_\_ ↑ Pancreatic enzyme secretion ↑ Gall Bladder Contraction Trophic affects on Exo. Pancreas ↓ Gastric emptying ↓ Gastric Acid Secretion Relaxation of Sphincter of Oddi Gastric receptive relaxation
CCK
