Gastric, Small Intestinal, and Colonic Motility Module (Quiz) Flashcards
anatomic divisions of the stomach
- fundus
- corpus/body
- antrum
- pylorus
functional divisions of the stomach
- proximal reservoir
- distal antrum pump
the musculature of the ________ is adapted to maintain tonic contraction and allow periods of relaxation while the muscles of the _________ contract phasically
- musculature of the proximal stomach
- while muscles of the antral pump contract
what is tonic contraction
- contraction for long periods of time
two functions of gastric reservoir
- accomodate ingested material during a meal
- maintain compressive force on ingested contents to push material towards antral pump
gastric accommodation occurs via ______ of the fundus which ______ gastric volume
- relaxation of the funds
- increases gastric volume
what happens if you don’t have appropriate coordinated accomodation
- early satiety
- nausea
- epigastric pain
3 types of relaxation
- receptive relaxation
- adaptive relaxation
- feedback relaxation
_________ relaxation is a reflex triggered by the act of swallowing through stimulation of ___________ which stimulate _______ motor neurons in the enteric nervous system via efferent _______ fibers
- receptive relaxation
- mechanoreceptors
- inhibitory motor neurons
- vagal fibers
_________ relaxation is a ______ reflex trigged by distention of the _______ by mechanoreceptors within the gastric wall
- adaptive relaxation
- vago-vagal reflex
- gastric reservoir
_________ relaxation is triggered by the presence of nutrients entering the small intestine
- feedback
gastric reservoir innervated by which neurons
of which nervous system
under which control
- excitatory and inhibitory motor neurons
- of enteric nervous system
- under control by efferent vagal fibers
what is the primary function of the antral pump
why
- trituration
- grinds particles small enough to empty into duodenum
3 phases of the antral pump
- propulsion
- emptying
- retropulsion
what happens during propulsion
- gastric action potentials create a leading and trailing contraction
- leadings contraction pushes bolus towards antrum which triggers contraction of pyloric muscle
- some material empties into duodenum
what happens during retropulsion
- trailing contraction pushes gastric contents against closed pylorus
- repulses contents back into reservoir
importance of antral pump
- prevents solid masses greater than 7 mm from entering duodenum
another important function of gastric motility
- delivery of gastric contents that does not overload digestive and absorptive functions of small intestine
the rate of gastric emptying is adjusted by ______ control to compensate for variations in _____, ______, and ______ of gastric contents
- neural control
- volume, composition, and physical state of gastric contents
speed of meals contains protein, fats, and carbs
- carbs leave stomach fastest
- then protein
- fats are slowest
rate of emptying also depends on the ________ pressure of material entering duodenum
- osmotic pressure
hyperosmolarity of the duodenal content is sensed by _______ that initiate a _______ in gastric emptying through neuronal feedback
- duodenal osmoreceptors
- decrease
BASICALLY ITS TOO PACKED TOGETHER SO YOU HAVE TO TAKE LONGER TO BREAK IT DOWN
which empty fastest, liquids or solids
- liquids empty fastest
3 small intestinal motility patterns
- interdigestive
- digestive
- power propulsion
when does the interdigestive state begin
- when digestion and absorption of nutrients are complete
the pattern of motility in the interdigestive state is characterized by ________
- migrating motor complex
migrating motor complex starts as __________ contractions arising from ________
- large-amplitude contractions
- distal stomach
path of the contractions
- distal stomach
- duodenum
- small intestine
- terminal ileum
3 phases of migrating motor complex
- silent period with no contractile activity
- irregularly occurring contractions
- regularly occurring contractions
phase II and III together make up the activity front within which _______ waves propel contents ______ through the lumen
- peristaltic waves propel contents distally through the lumen
as one activity front _____ in the ileum another one ____ in the antrum
- ends in the ileum
- begins in the antrum
cycling of the migrating motor complex occurs until
which
- more food is ingested
- ceases the migrating motor complex
how migrating motor complex helps the gallbladder
- coordinated contraction of gallbladder to deliver bile to duodenum
- bile reabsorbed in terminal ileum
- minimizes the accumulation of bile in the gallbladder and increases movement of bile acids during the interdigestive state
- prevents formation of gallstones
how migrating motor complex helps intestinal lumen
- clears indigestible debris from lumen in interdigestive state
how migrating motor complex helps small intestine
- prevents overgrowth of microorganisms in small intestine because lumen contents are always moving
migrating motor complex controlled by which system
- enteric nervous system
during digestive state a ______ pattern of motility replaces the migrating motor complex
- mixing pattern of motility (segmentation)
_____ muscle contraction in short propulsive segments are separated on either end by ____ receiving segments
importance
- circular muscle contraction
- separated by relaxed receiving segments
- propulsive segment sends chyme in both directions to receiving segments
what happens in receiving segments
- stirring and mixing occur
importance of segmentation
- small bowel contents have greater time in contact with mucosa which increases absorption
_______ involves strong, long-lasting contractions of ___ muscle that propagate for extended distances along the ____
- power propulsion
- circular
- small and large intestine
power propulsion occurs in the _____ direction during emesis in the small intestine and in the ______ direction in response to noxious stimulation in both small and large intestine
- retrograde (backwards) during emesis
- antegrade (forwards) during noxious stimuli
symptoms associated with power propulsions
- abdominal cramping
- diarrhea
how is power propulsion a defensive adaptation
- rapid clearance of undesirable contents from the small intestine lumen
between small and large intestine, which contains mixture of remnants of several meals
- large intestine
primary motility pattern of the colon
- ring-like contraction of circular muscle that divide colon into haustra pockets
difference between haustration in large intestine and segmentation of small intestine
- contracting and receiving segments in haustration remain in their states much longer
- haustration form and reform at different sites
haustration during fasting
- propulsion in both directions
- reabsorb water without net forward propulsion
haustration during net forward propulsion
purpose
- contents of one haustra pushed into adjacent region where a second haustral pocket is
- compacts feces
what triggers power propulsion in the large intestine
- increased delivery of ileal chyme into ascending colon
- irritant laxatives
power propulsion of feces in the healthy bowel typically begins in the _________ colon
causing
- mid-transverse
- causes cessation of haustration
what part of the colon is the primary location of water and electrolyte absorption
- transverse colon
importance of sigmoid colon and rectum
- storage of stool until time for defecation
