Exam 4: Lecture 54: Gastrointestinal Moltility Flashcards
define motility
move things around and mix substances together
refers to the contractions and relaxation of walls and sphincters of the GIT
motility
contractile tissue of the GIT is composed of
smooth muscle
Pharynx, upper 1/3 of esophagus and external sphincter is composed of
striated muscle
what allows for very smooth contraction
unitary smooth muscle
cells are electrically coupled via gap junctions. This allows for fast ________
contraction
shortening of ring of smoot muscles is controlled by ________ muscles
- decreased diameter
circular
shortening in longitudinal direction is controlled by ________ muscles
longitudinal
decrease in diameter of segment and mixing of digestia is controlled by ________ muscle
circular
decrease length of segments that allows digestia to move along the esophagus controlled by ________ muscles
longitudinal
periodic contractions folled by relaxations is also called
phasic contraction
how do you maintain a constant level of contraction or tone without regular relaxation
tonic contraction
________ ________ are a unique feature of the GI smooth muscle
slow waves
oscillating depolarization and repolarization of membrane potnetial of smooth muscle cells are determine by ________ waves
slow
slow wave potential may or may not have bring membrane potential to ________
threshold
frequency of slow waves varies among
3-12/min
frequency of slow waves in the stomach are
3/min
the slowest slow waves are produced in the ________
stomach
frequency of slow waves in the duodenum are
12/min
where is the frequency of the wave determined
top of the wave
origin of slow waves are the ________ cells
cajal cells
intersitial cells of cajal is in the ________ plexus
myenteric plexus
depolarization occurs ________
spontaneously
once in cells, the message travels ________
rapidly
origin of the slow waves are considered the ________ of the GI smooth muscles
pacemaker
depolarization phase and maintence of the ________ is a mechanism of slow waves
plateau
at the top of the wave, Ca2+ (calcium channels) maintain the ________
plateau
opening of K+ channels starts ________
repolarization
chewing / mixing of food and addition of salvia makes it easier to ________
swallow
mixes ingested carbohydrates with salviary ________ during mastication
amylase
amylase breaks down
fat
initiated by food in the mouth
involuntary component
________ in mouth relay to brainstem when to define when something is present
mechanoreceptors
can override reflex chewing at any time
voluntary component
initiated voluntarily in the mouth is called ________
deglutition
receptors near ________ detect and send info via the vagus nerve and glossopharyngeal nerves
pharynx
swallowing center is controlled in the
medulla
voluntary at first, then becomes ________
involuntary
voluntary at first, then becomes involuntary is defined as the ________ phase
Oral phase
________: course bouls of food towards the back of mouth: lots of receptors and swallowing center = ________ swallowing takes over
tongue
involuntary
involuntary, propel bolus from mouth through the pharynx to esophagus in 4 steps is defined as
pharynx phase
controlled by swallowing reflex and the enteric nervous system is defined as
esophagus phase