Stomach 1 Flashcards
name the two functional regions of the stomach (and their main parts)
proximal- fundus and proximal body
distal- distal body and antrum (pylorus)
the proximal region (orad stomach) is responsible for what?
receiving ingested meal
the distal region (caudad stomach) is responsible for what
contractions that mix food and propel it into duodenum
what are the three functions of the stomach?
storage
mixing
emptying
what occurs in the stomach during food storage
proximal stomach relaxes to accommodate ingested meal- via receptive relaxation
pressure slowly returns to basal level
stomach can hold up to 1.5 L w/ little change in pressure
receptive relaxation (what is it, what mediates it, how is it abolished)
process by which the proximal stomach relaxes to accommodate ingested meal
mediated by vagovagal reflex
abolished by vagotomy
the vagovagal reflex is initiated by what?
distention of the stomach
what occurs in the stomach during mixing
presence of food causes distal stomach to increase contractions
this mixes food with gastric sections and reduces size of particles
food mixed into pasty consistency (chyme)
what is chyme?
semifluid mass of partly digested food passed from the stomach to small intestine (made during mixing in stomach)
what occurs in stomach during emptying
distal stomach contracts to propel food into duodenum
peristaltic contractions originate where and proceed how?
originate in pacemaker region (midstomach)
proceed distally
a peristaltic contractions move distally toward pylorus what happens to velocity and force of the contractions?
they both increase
retropulsion (what is it)
process by which most of chime is propelled back into the stomach to be mixed
due to wave on contractions closing distal antrum and pyloric sphincter before chyme reaches there
the wave of peristaltic contractions does what to distal antrum and pyloric sphincter
closes them before the chyme can reach there
causes retropulsion
what occurs during fasting (contractions wise and how often)
contractions called migrating myoelectric complexes occur at 90 minute intervals
migrating myoelectric complexes (what do they do)
occur every 90 minutes during fasting
clear the stomach of any residual food
cause hunger contractions if stomach has been empty for about 2 hours
how are migrating myoelectric complexes abolished
eating
hunger pangs (when do they start and how long do they last)
start 12-24 hours after last meal
continue for about 3-4 days before subsiding
emptying of the stomach occurs when?
chyme decomposed into small enough pieces to fit through pyloric sphincter
following a normal mixed meal emptying of the stomach may take about how long, and is dependent on what?
about 3 hours
depends on type of food ingested
place the following in order of fastest to slowest in terms of emptying from the stomach:
protein-rich food
carbohydrate-rich food
fat-rich food
carbohydrate-rich food (fastest of these three) > protein-rich food > fat-rich food (slowest of these three)
between liquids and solids which empty from the stomach fastest
liquids
the rate of emptying has what type of relationship with the pressure in the proximal stomach (which increases slowing during digestive period)
inversely proportional
gastric emptying is controlled mostly by what?
signals from duodenum
gastric emptying is inhibited by what stimuli?
high [H+] fat or protein digestion products non-isotonic solutions increases distention of proximal stomach increase pressure in proximal small intestine
gastric emptying prevents what? (in terms of the flow of chyme)
prevents flow of chyme from exceeding ability of intestine to handle it
Gastroparesis (what is it, what does it produce, what causes it
impaired/ delayed emptying
produces symptoms of fullness, loss of appetite, nausea, vomiting
most common cause is diabetes