CPPS 303_Pancreatic Digestive Functions_Intestinal Fluid & Electrolyte Movement_March 3 & 5_2025 Flashcards
What are the pancreatic secretions mainly responsible for?
Control of blood sugar levels
Pancreatic secretions include both endocrine (insulin, glucagon) and exocrine components.
What percentage of the pancreatic mass is comprised of exocrine glands?
99%
The pancreas is primarily an exocrine organ with a small endocrine component.
What are zymogens and what role do they play in digestion?
Inactive precursors of digestive enzymes for protein digestion
Zymogens include trypsinogen and chymotrypsinogen, which are activated in the intestine.
List the active digestive enzymes released by the pancreas.
- Amylase
- Lipase
- Colipase
- Nucleases (RNAase, DNAase)
These enzymes are released in their active forms and are crucial for digestion.
What is the primary physiological function of alkaline pancreatic juice?
Neutralize acidic gastric content (chyme) in the duodenum
This is essential for proper enzyme function in the small intestine.
How is bicarbonate ion (HCO3-) secreted by pancreatic duct cells?
Through a Cl–HCO3- exchanger at the apical membrane
This process helps create alkaline pancreatic juice.
What triggers the secretion of bicarbonate in the pancreas?
CO2 combines with H2O to form carbonic acid
This reaction is facilitated by carbonic anhydrase.
What role does cytosolic calcium play in pancreatic secretion?
Coordinates exocytosis of cytosolic granules
Calcium acts as a second messenger for the secretion of proteins.
What stimulates pancreatic secretion during the fed state?
Multiple stimuli including CCK, Ach, and gastrin
These factors ensure adequate enzyme release corresponding to food intake.
What is the average daily fluid input into the small intestine?
8.5 L
This includes contributions from oral intake and GI secretions.
Where does the majority of water and electrolyte absorption occur in the GI tract?
Small intestine
The small intestine is primarily responsible for absorbing dietary nutrients and fluids.
What is the average absorption rate for the small intestine?
~ 6.5 L per day
This value reflects the efficiency of nutrient and fluid absorption.
What is the role of Na+ absorption in the small intestine?
Coupled with nutrient absorption via Na+-Glucose and Na+-Amino acid cotransporters
This process is vital for efficient nutrient uptake.
What is the mechanism of Na+ absorption related to nutrient absorption?
Secondary active transport
Utilizes the sodium gradient established by Na+-K+ ATPase.
What are the three mechanisms of Na+ absorption not related to nutrient absorption?
- Na+-H+ exchanger
- Na+-HCO3- and Cl–HCO3- exchanger
- Epithelial Na+ channels
These mechanisms help maintain electrolyte balance in the intestines.
What is the function of aldosterone in Na+ absorption?
Enhances electrogenic apical Na+ absorption and basolateral Na+-K+-ATPase activity
This promotes sodium conservation in the distal colon.
Fill in the blank: The pancreas releases pancreatic enzymes during the _______ state.
[fed]
The secretion of enzymes increases significantly after food intake.
True or False: The colon secretes digestive enzymes.
False
The colon primarily absorbs fluids and electrolytes without secreting digestive enzymes.
Where does Na+ absorption occur?
Distal colon
What enhances electrogenic apical Na+ absorption?
Aldosterone
What is the function of basolateral Na+-K+-ATPase?
It enhances Na+ absorption against high concentration gradient
What are the two pathways for Cl- absorption?
- Paracellular
- Transcellular
What drives passive Cl- absorption?
Electrochemical gradient
What is the primary mechanism for Cl- absorption between meals?
Na+-H+ & Cl–HCO3- exchanger
