BIOL 373 Final Exam Q & As (Verified
Answers) 2026
What are the functions of the GI system? - Correct Answers
✅1. digestion - break macromolecules (nutrients) into forms
that can be transported across the epithelium
2. absorption - transport nutrients, water, ions, vitamins
across epithelium
3. secretion - release of enzymes into the gut lumen (heavily
regulated)
4. motility - keep the gut contents moving (heavily regulated)
5. maintain water balance - balance between secretion and
reabsorption
What are some problems faced by the GI tract regarding its
function? - Correct Answers ✅1. need to digest
marcomolecules but not itself
-break down of barriers? -> peptic, duodenal ulcers
2. needs to allow entry of digested nutrients but not
pathogens
-GI lining is largest area of contact between internal and
external environments
-protection from pathogens mediated by:
+ epithelial barrier
+ mucus
+ digestive enzymes
+ acid
,BIOL 373 Final Exam Q & As (Verified
Answers) 2026
+ gut associated lymphoid tissue (GALT) - needs to react to
pathogens but not foreign proteins associated with food
Anatomy - Correct Answers ✅1. stomach
2. small intestine - duodenum, jejunum, ileum
3. large intestine - colon, rectum
Muscosal surface amatony - Correct Answers ✅1. mucosa -
epithelium, lamina propria, muscularis mucosa
2. submucosa - Meissner's (Submucosal) plexus
3. smooth muscle layers - circular muscle, auerbach's
(myenteric) plexus, longitudinal muscle
4. serosa
Differences between small intestine and stomach anatomy? -
Correct Answers ✅stomach:
-gastric glands
-oblique muscle
small intestine:
-villi, crypt
-Peyer's patch (in mucosa)
What features increase surface area? - Correct Answers
✅stomach - gastric glands
,BIOL 373 Final Exam Q & As (Verified
Answers) 2026
small intestine - crypts
What are the 2 major patterns of contraction for gut motility?
- Correct Answers ✅1. peristalis - moving food from mouth
to anus (forward movement)
2. segmental contractions - mixing/churning, maximizes
exposure to digestive enzymes and epithelium (little or no
net forward movement)
these occur during/after a meal
Tonic vs. phasic contractions - Correct Answers ✅-most gut
muscle is a single unit smooth muscle, connected by gap
junctions
-certain regions are tonically contracted for minutes to hours
+ smooth muscle sphincters
+ anterior part of the stomach (keeps food from moving
backwards)
-other regions undergo phasic contractions
+ posterior stomach
+ small intestine
Migrating motor complexes - Correct Answers ✅-a series of
contractions that begin in the empty stomach and end in the
large intestine (~90 minutes)
, BIOL 373 Final Exam Q & As (Verified
Answers) 2026
-"house keeping" function -> sweeps food remnants and
bacteria out of GI tract and into the large intestine
-between meals
Slow wave potentials - Correct Answers ✅-slow waves
similar to pacemaker potentials in cardiac muscle except
much less frequent, and do not necessarily reach threshold
+ below threshold = no contraction
+ above threshold = opening of voltage-gated Na+ channels
-> action potentials -> contraction
-degree of contraction is graded according to amount of
Ca2+ that enters
+ longer wave = more time for Ca2+ to enter = larger
contraction
+ amplitude and duration of contraction influenced by:
neurotransmitters (autonomic input), hormones, paracrine
factors
Interstitial cells of cajal - Correct Answers ✅-slow wave
frequency varies in different regions of the tract
+ more frequent in duodenum vs. stomach
+ set by 'pacemaker cells' between smooth muscle layers
"interstitial cells of Cajal"
What is secreted? - Correct Answers ✅-water and ions
(secreted into lumen then reabsorbed)
Answers) 2026
What are the functions of the GI system? - Correct Answers
✅1. digestion - break macromolecules (nutrients) into forms
that can be transported across the epithelium
2. absorption - transport nutrients, water, ions, vitamins
across epithelium
3. secretion - release of enzymes into the gut lumen (heavily
regulated)
4. motility - keep the gut contents moving (heavily regulated)
5. maintain water balance - balance between secretion and
reabsorption
What are some problems faced by the GI tract regarding its
function? - Correct Answers ✅1. need to digest
marcomolecules but not itself
-break down of barriers? -> peptic, duodenal ulcers
2. needs to allow entry of digested nutrients but not
pathogens
-GI lining is largest area of contact between internal and
external environments
-protection from pathogens mediated by:
+ epithelial barrier
+ mucus
+ digestive enzymes
+ acid
,BIOL 373 Final Exam Q & As (Verified
Answers) 2026
+ gut associated lymphoid tissue (GALT) - needs to react to
pathogens but not foreign proteins associated with food
Anatomy - Correct Answers ✅1. stomach
2. small intestine - duodenum, jejunum, ileum
3. large intestine - colon, rectum
Muscosal surface amatony - Correct Answers ✅1. mucosa -
epithelium, lamina propria, muscularis mucosa
2. submucosa - Meissner's (Submucosal) plexus
3. smooth muscle layers - circular muscle, auerbach's
(myenteric) plexus, longitudinal muscle
4. serosa
Differences between small intestine and stomach anatomy? -
Correct Answers ✅stomach:
-gastric glands
-oblique muscle
small intestine:
-villi, crypt
-Peyer's patch (in mucosa)
What features increase surface area? - Correct Answers
✅stomach - gastric glands
,BIOL 373 Final Exam Q & As (Verified
Answers) 2026
small intestine - crypts
What are the 2 major patterns of contraction for gut motility?
- Correct Answers ✅1. peristalis - moving food from mouth
to anus (forward movement)
2. segmental contractions - mixing/churning, maximizes
exposure to digestive enzymes and epithelium (little or no
net forward movement)
these occur during/after a meal
Tonic vs. phasic contractions - Correct Answers ✅-most gut
muscle is a single unit smooth muscle, connected by gap
junctions
-certain regions are tonically contracted for minutes to hours
+ smooth muscle sphincters
+ anterior part of the stomach (keeps food from moving
backwards)
-other regions undergo phasic contractions
+ posterior stomach
+ small intestine
Migrating motor complexes - Correct Answers ✅-a series of
contractions that begin in the empty stomach and end in the
large intestine (~90 minutes)
, BIOL 373 Final Exam Q & As (Verified
Answers) 2026
-"house keeping" function -> sweeps food remnants and
bacteria out of GI tract and into the large intestine
-between meals
Slow wave potentials - Correct Answers ✅-slow waves
similar to pacemaker potentials in cardiac muscle except
much less frequent, and do not necessarily reach threshold
+ below threshold = no contraction
+ above threshold = opening of voltage-gated Na+ channels
-> action potentials -> contraction
-degree of contraction is graded according to amount of
Ca2+ that enters
+ longer wave = more time for Ca2+ to enter = larger
contraction
+ amplitude and duration of contraction influenced by:
neurotransmitters (autonomic input), hormones, paracrine
factors
Interstitial cells of cajal - Correct Answers ✅-slow wave
frequency varies in different regions of the tract
+ more frequent in duodenum vs. stomach
+ set by 'pacemaker cells' between smooth muscle layers
"interstitial cells of Cajal"
What is secreted? - Correct Answers ✅-water and ions
(secreted into lumen then reabsorbed)
