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59 Cards in this Set

  • Front
  • Back
What 2 fibers is the muscularis composed of
longitudinal
Circular
how long and wide is a single muscle fiber
200-500um long
2-10um diameter
what are the muscle fibers packaged into, approximately how many,and what direction do they lay
Bundles
1000 fibers in a bundle
arranged in parrallel
What does each muscle bundle function as, what allows this function
syncitium (fibers behave as 1
gap junctions
What is the importance of gap junctions
tunnels, allow rapid propogation of electrical signals from cell to cell, w/out x-ing cell membrane
Transmission of electrical signals in the gut,occurs the fastest, in which direction
Lengthwise "end to end"
What are the other ways transmission of electrical signals can occur, which are not the best (fastest)
side to side transmission
bundle to bundle
circular fibers to longitudinal
An electrical signal produced any where will travel
Everywhere, all transmission routes active,yet lengthwise is major
Two types of electrical activity in the gut
slow waves
spikes
RMP of the gut between what
What is the avg RMP
What is RMP of skeletal muscle
-50 to -60mv
avg -56mv
-70mv
In skeletal muscle the RMP is ___________, yet in the smooth muscle of the gut the RMP is___________
constant
slow undulating changes
order the rate of slow waves from greatest to least in Gut
duodenum 12/min
illeum 8-9/min
stomach 3/min
What is thought to cause slow waves?
Unclear, due to changes of Na/K pump, Na influx occurs uphase possiple more than K
Spikes are true ______. The depend on _______. What must occure for spike to happen. What is threshold
Action potentials
slow waves
slow waves reach threshold
-40mv
The higher the slow wave above threshold it is, the more _______ you get. What the difference between regular skelatal action potentials
spikes
AP in gut are graded not all or none
What is the rate of spikes (AP) in the gut
1-10 spikes/sex
how long does an invididual spike last. how does this compare to a regular AP
10-20ms
Spike AP are 10 to 40x longer than regular AP
Longer means slower
What causes spikes to occur
Large influx of Ca ions
small influx of Na
What are the channels that allow Ca and Na movement in cell
Ca/Na channels
No co transport, permeable
Why does a spike(AP) take much longer than a regular AP
the Ca/Na channels are slow to open and slow to close
What does Hypopolarize mean
(depolarize), less polarized, moves membrane towards threshold (less negative)
Hypopolarization will make the muscle fiber
more excitable
What does hyperpolarization mean
Makes membrane more negative, away from threshold, similar to IPSP
What are the 3 ways to make membrane potential hypopolarized (more excitable)
Stretching muscle fibers
ACH
Gut hormones
How do you hyperpolarize a membrane
Norepi/epi,,,,, sympathetic
What are the 2 types of contractions in the gut
Rhytmic and tonic
Rhytmic contractions
spike frequency (AP)is proportional to the rythmic contractions, only last seconds
Tonic contractions
Contractions persist, much longer, min to hours
What is the stimulus and for all muscle contractions
Ca influx into the cells (raises Ca levels)
what is the difference in Ca in the gut verses regular muscle (skeletal)
skeletal= storage of ca sarcoplasmic reticulum
Smooth= Ca diffuses into cell no storage
What are the three things which lead to a tonic contraction
continous spike potentials
Hormones
Continous entry of Ca,*not associated with electrical act, really unclear
Overview
Have tonic and rythmic contractions, the two things which contract are the circular and longitudinal muscles
Neuronal control of the gut
Enteric nervous system, special
The ENS innervates from ___________, consists of _________ neurons
esophogus to anus
100,000,000 million neurons
Neurons of ENS control
Movement
Secretions
Blood flow
What are the two plexuses of ENS
Myenteric (aurbachs)
Submucosal (meysners)
Myenteric plexus controls ________, and is located b/ween the _______ and ______ muscle layers
movement rates, longitudinal and circular muscle layers
Submucosal plexus controls ______ and ______
secretions and blood flow
the motor neurons from CNS can act _____ or _____ to stimulate muscle contraction
directly or indirectly
What are the steps of Indirect stimulation of muscle by CNS
CNS ----ENS plexus---stim muscle
The gut has sensory neurons for each of the following to carry signals
note (have many options to respond to sensations)
1prevertebral ganglia of Symp Nerv system (skips CNS)
2 Normal route into cord to CNS
3Directly go to brain stem (vagus nerve)
4 innervate both plexuses
What are the three types of sensations (monitored) detected by the sensory neurons of the gut
1. irritations of mucosa (diahhrea)
2. Stretch
3. chemoreceptors
Myenteric plexus is associated with the _______
muscle wall
Stimulation of Myenteric Plexus causes what
food to move faster (increase motility)
Inhibition of Myenteric plexus causes
food to move slower (decrease of motility)
what are the 5 ways to increase motility in the gut
^ rate of tonic contractions
^ force (amplitude) of Rythmic contractions
^ fz of Rythmic contractions
^ v of electrical conduction
inhibit sphincters that block movement
Submucosal plexus controls ______ tunic layers and is involved with _______
inner
secretion rates
12 NT's released at gut in assoc. w/Plexuses
ACH, Norepi, ATP, Serotonin, Dopamine, cholecystokinin, Substance P, Vasoactive intestinal polypeptide, somatostatin, leu-enkephalin, Net-enkephalin, bombesin
______ and ______ do most of the work on the gut the other _______
ACH and Norepi/epi
moonlight
How many reflexes are involve in GI
3
How are the reflexes categorized
anatomically
reflex innvervated soley in the ______, and the CNS is never ______. What are the 4 things drivin this way
ENS
informed
secretions,peristalisis,mixing,and local inhibitions
Reflex from ____ to __________, then back to gut.
gut to prevertebral symp ganglia,
What are some examples of reflex from gut to Symp ganglia and back
gastrocholic reflex
introgastric reflex
colonoileal reflex
Gastrocholic reflex
gut---symp ganglia--gut
stomach to colon
causes defecation
strectch stomach clears colon
Introgastric reflex
gut---symp--gut
SI and LI to stomach
keeps stomach from overfilling (regulates)
Introgastric reflex regulates the overfilling in the stomach by _______ the stomach when _______ is full
inhibiting
Intestine
colonoileal reflex
gut---symp---gut
colon to SI
The colonoileal reflex inhibits the ______ when food enters the _______.
SI
LI