BIOL 373 Final Exam Questions With Complete
Solutions
What are the functions of the GI system? - CORRECT ANSWER✔✔-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
| | | | | | | | | | | | | |
ANSWER✔✔-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
|
+ gut associated lymphoid tissue (GALT) - needs to react to pathogens but not
| | | | | | | | | | | | | |
foreign proteins associated with food
| | | |
,Anatomy - CORRECT ANSWER✔✔-1. stomach | | | |
2. small intestine - duodenum, jejunum, ileum
| | | | | | |
3. large intestine - colon, rectum
| | | | |
Muscosal surface amatony - CORRECT ANSWER✔✔-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
| | | | | | | | |
ANSWER✔✔-stomach: |
-gastric glands |
-oblique muscle | |
small intestine:
|
-villi, crypt
|
-Peyer's patch (in mucosa) | | |
What features increase surface area? - CORRECT ANSWER✔✔-stomach - gastric
| | | | | | | | | |
glands
small intestine - crypts
| | |
What are the 2 major patterns of contraction for gut motility? - CORRECT
| | | | | | | | | | | | |
ANSWER✔✔-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 ANSWER✔✔--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 ANSWER✔✔--a series of contractions that
| | | | | | | | |
begin in the empty stomach and end in the large intestine (~90 minutes)
| | | | | | | | | | | | | |
-"house keeping" function -> sweeps food remnants and bacteria out of GI tract
| | | | | | | | | | | | |
and into the large intestine
| | | | |
-between meals |
Slow wave potentials - CORRECT ANSWER✔✔--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 ANSWER✔✔--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 ANSWER✔✔--water and ions (secreted into lumen
| | | | | | | | | | |
then reabsorbed)|
-enzymes
-mucus
-bile (from liver)
| |
-saliva
How are water and ions secreted? - CORRECT ANSWER✔✔--mostly via
| | | | | | | | | |
membrane transporters |
-water follows osmotic gradient
| | |
-water and ions in some regions can also pass between cells (paracellular
| | | | | | | | | | | |
pathway) |
Solutions
What are the functions of the GI system? - CORRECT ANSWER✔✔-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
| | | | | | | | | | | | | |
ANSWER✔✔-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
|
+ gut associated lymphoid tissue (GALT) - needs to react to pathogens but not
| | | | | | | | | | | | | |
foreign proteins associated with food
| | | |
,Anatomy - CORRECT ANSWER✔✔-1. stomach | | | |
2. small intestine - duodenum, jejunum, ileum
| | | | | | |
3. large intestine - colon, rectum
| | | | |
Muscosal surface amatony - CORRECT ANSWER✔✔-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
| | | | | | | | |
ANSWER✔✔-stomach: |
-gastric glands |
-oblique muscle | |
small intestine:
|
-villi, crypt
|
-Peyer's patch (in mucosa) | | |
What features increase surface area? - CORRECT ANSWER✔✔-stomach - gastric
| | | | | | | | | |
glands
small intestine - crypts
| | |
What are the 2 major patterns of contraction for gut motility? - CORRECT
| | | | | | | | | | | | |
ANSWER✔✔-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 ANSWER✔✔--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 ANSWER✔✔--a series of contractions that
| | | | | | | | |
begin in the empty stomach and end in the large intestine (~90 minutes)
| | | | | | | | | | | | | |
-"house keeping" function -> sweeps food remnants and bacteria out of GI tract
| | | | | | | | | | | | |
and into the large intestine
| | | | |
-between meals |
Slow wave potentials - CORRECT ANSWER✔✔--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 ANSWER✔✔--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 ANSWER✔✔--water and ions (secreted into lumen
| | | | | | | | | | |
then reabsorbed)|
-enzymes
-mucus
-bile (from liver)
| |
-saliva
How are water and ions secreted? - CORRECT ANSWER✔✔--mostly via
| | | | | | | | | |
membrane transporters |
-water follows osmotic gradient
| | |
-water and ions in some regions can also pass between cells (paracellular
| | | | | | | | | | | |
pathway) |
