Unit 6A Part 1 and 2 - Screencasts Flashcards
What are the four major functions of the GI system?
a) Absorption, filtration, elimination, secretion
b) Digestion, reabsorption, transport, filtration
c) Secretion, motility, digestion, absorption
d) Excretion, metabolism, diffusion, reabsorption
c) Secretion, motility, digestion, absorption
Explanation: These core GI functions allow breakdown and movement of nutrients, and their absorption into the body.
What does it mean to say that the GI tract is ‘outside the body’?
a) It is exposed to the environment
b) It is sterile
c) Nothing can cross into it
d) Material is not internal until it crosses the epithelium
d) Material is not internal until it crosses the epithelium
Explanation: GI tract contents are considered external until absorbed across epithelial barriers.
What structural adaptations increase surface area in the small intestine?
a) Microvilli only
b) Plicae, villi, and microvilli
c) Rugae and folds
d) Goblet cells and ducts
b) Plicae, villi, and microvilli
Explanation: These three nested structures dramatically increase the absorptive surface area of the intestine.
What are Peyer’s patches?
a) Enzyme-secreting glands
b) Hormone receptors
c) Immune nodules in the small intestine
d) Muscular valves
c) Immune nodules in the small intestine Explanation: These lymphoid aggregates provide localized immune surveillance, especially in the ileum.
What is the role of the interstitial cells of Cajal?
a) Set the rhythm for slow wave potentials
b) Act as gut immune cells
c) Secrete acid in the stomach
d) Absorb nutrients
a) Set the rhythm for slow wave potentials Explanation: These pacemaker-like cells coordinate gut motility through rhythmic depolarizations.
How does the pancreas neutralize stomach acid in the small intestine?
a) Acid absorption
b) Bicarbonate secretion from duct cells
c) HCl secretion
d) Lacteal fluid release
b) Bicarbonate secretion from duct cells Explanation: Pancreatic duct cells secrete large amounts of HCO₃⁻ into the duodenum to neutralize gastric acid.
What drives water secretion into the GI tract?
a) ATP hydrolysis
b) Sodium/potassium pump only
c) Water channels in microvilli
d) Chloride ion movement across epithelium
d) Chloride ion movement across epithelium Explanation: Chloride secretion through CFTR drives paracellular Na⁺ movement and water via osmosis.
Which channel is defective in cystic fibrosis?
a) CFTR chloride channel
b) NKCC transporter
c) Na⁺/K⁺ ATPase
d) Aquaporin
a) CFTR chloride channel Explanation: CFTR dysfunction impairs Cl⁻ and water secretion, resulting in thick mucus and blocked ducts.
What is the alkaline tide?
a) Acid secretion into the stomach lumen
b) Bicarbonate released into blood after acid secretion
c) Sodium retention post-meal
d) Bile acid absorption
b) Bicarbonate released into blood after acid secretion Explanation: Parietal cells secrete H⁺ into the stomach and HCO₃⁻ into the blood, temporarily raising blood pH.
How are zymogens activated safely?
a) Secreted directly as active enzymes
b) Activated at the brush border or in lumen
c) Bound to immune cells
d) Activated in pancreas
b) Activated at the brush border or in lumen Explanation: Enzymes are released in inactive forms and activated only in the intestinal lumen to prevent self-digestion.
