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