Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
64 Cards in this Set
- Front
- Back
|
What is Multiunit Smooth Muscle?
|
-Each Muscle Cell Receives its own Nerve Supply
-Much Finer Control |
|
|
What is Unitary Smooth Muscle? How does this work?
|
-Muscle acts as a Unit
-Cells are Electrically Coupled via Gap Junctions |
|
|
Which type of Muscle is more prevalent in the GI Tract, Unitary or Multiunit? Why?
|
-Unitary
-Don't need Fine Control |
|
|
What is a Slow Wave? What does it establish?
|
-Spontaneous Oscillations in Membrane Potential
-Establishes Basal Tone |
|
|
How do slow waves cause APs?
|
-They Don't
-Spike Potentials cause APs |
|
|
What causes Contraction of Muscle in the GI Tract?
|
-Spike Potentials
|
|
|
What do the ICC Cells do?
|
-Generate Slow Waves
|
|
|
How do Muscle Cells generate Slow Waves?
|
-They Don't
-ICC Cells do |
|
|
How is the 3D Network in the GI Tract Organized? What Layers enclose ICC Cells?
|
Found:
-In between Smooth Muscle -In the Plexi |
|
|
What is the purpose of the 3D Network of ICC Cells?
|
Allows ICCs to:
-Modify Action of ENS -Alter Motility Patterns |
|
|
How are ICC Cells, Smooth Muscle Cells, and Neurons of the ENS Electrically Coupled?
|
-Long Extensions from ICCs
|
|
|
GI TRACT CAN CONTRACT WITHOUT ANY NERVE STIMULATION
|
Kassage Kuo:
GI TRACT CAN CONTRACT WITHOUT ANY NERVE STIMULATION |
|
|
What are a group of ICC Cells close together called?
|
Pacemaker
|
|
|
What causes a Spike Potential?
|
Increase in Amplitude of Slow Waves
|
|
|
What results if the number of Spikes increases?
|
Stronger Contractions
|
|
|
What kinds of Electrical Effects would Increase Motility? What kinds of Stimuli/NTs would cause this?
|
-Increased Depolarization
-Stretch -ACh -Parasympathetics |
|
|
What kinds of Electrical Effects would Decrease Motility? What kinds of Stimuli/NTs would cause this?
|
-Increased Hyperpolarization
-NE -Sympathetics |
|
|
How are ICC Cells depolarized?
|
By Spontaneous Inward Currents
|
|
|
Describe the Depolarization of Smooth Muscle Cells.
|
-Spike Potentials result in ICC Cells
-Activates L-Type Ca2+ Channels in Smooth Muscle Cells -Calcium comes into the Cell -Allow Contraction |
|
|
What directly controls the ICC Cells?
|
ENS
|
|
|
What is the Rate of Slow Wave Production Known as in the GI Tract? What does this Mechanism Control?
|
-Basic Electrical Rhythm
-Rate of Contraction of the GI Tract |
|
|
Where is the BER Fastest? Slowest?
|
-Duodenum - 11 cpm
-Stomach - 3cpm |
|
|
What are the 3 Phases of Swallowing?
|
-Oral Phase
-Pharyngeal Phase -Esophageal Phase |
|
|
Where is the Swallowing Reflex Center found?
|
Medulla
|
|
|
Which phase of Swallowing is Voluntary and Pushes a Bolus of Food into the Pharynx?
|
Oral Phase
|
|
|
Describe the Oral Phase of Swallowing.
|
-Voluntary
-Tongue Pushes Food into Pharynx |
|
|
What Happens during Pharyngeal Phase of Swallowing?
|
-Bolus Touches the Pharynx
-Stimulates Involuntary Movement -Pushes Bolus Down |
|
|
What do the Upper Constrictors do during the Pharyngeal Phase of Swallowing? Middle Constrictors?
|
-Push Food Down
-Push down to the Esophagus |
|
|
Why does the Epiglottis close during swallowing?
|
Don't want food in the lungs fool!
|
|
|
Describe what happens during the Esophageal Phase of Swallowing.
|
-Food is pushed down the esophagus
-UES closes -Peristalsis propels the bolus to the Stomach |
|
|
What are the different types of Peristalsis involved in the Esophageal Phase of Swallowing? When are they used?
|
-Primary Peristalsis - Push Food Down
-Secondary Peristalsis - Clears Bolus if Primary could not |
|
|
What is the LES doing during swallowing and after food has entered the stomach? Why?
|
-Opens to allow food through
-Closes to stop reflux |
|
|
Where in Relation to the Diaphragm does the LES lie?
|
Below the Diaphragm
|
|
|
What happens at the UES when Swallowing begins? Why?
|
-UES Opens
-Pressure at UES Drops -Hs to Allow Food in |
|
|
What happens to the UES after Food Enters the Esophagus? Why?
|
-UES Closes
-Don't want food going back up |
|
|
What happens to the Pressure at a given point just before Food arrives? What about after it moves past it? Explain
|
-Pressure drops to facilitate movement towards the point
-Pressure Increase to push Bolus forward |
|
|
What must happen to allow food into the stomach? How does this initially happen?
|
-LES must open to allow travel in
-Starts to Open Reflexively before Food Reaches it |
|
|
Described the Muscle Composition and Innervation of the Esophagus.
|
-Upper 1/3 - Skeletal Muscle - Vagal Fibers
-Lower 2/3 - Smooth Muscle - ENS Interneurons |
|
|
Is Peristalsis in the Esophagus dependent on the Vagus Nerve? Why or why not?
|
-No
-Directly Innervated by the ENS -Vagus just modifies |
|
|
Why is the Basal Tone of the LES Higher than other Muscle of the Esophagus
|
-Pressure in the Abdomen is Higher than in the Thorax
-Will force the LES Open -Needs to maintain a stronger tone to hold it shut |
|
|
What are the 2 Mechanisms of Control for the Lower Sphincter? What Controls each one?
|
-Myogenic Properties - Only from Muscle, Independent of Neural Influences
-Cholingergic Excitatory Tone - High, Controlled by ACh |
|
|
What happens to the LES during Reflex Activities? What are some examples of Reflex Activities?
|
-Relaxes
-Belching -Gastroesophageal Reflex |
|
|
What is the Relaxation of LES Modulated by? Which NTs are believed to be the cause of this?
|
-Vagal "Long-Loop" Neural Reflex
-Inhibitory NTs - Believed to be VIP and/or NO |
|
|
What is the "Bird-Beak" Sign and what is it indicative of?
|
-A Stenosis at the LES
-Achalasia |
|
|
What is Achalasia? How does it results?
|
-Loss of Inhibitory mechanisms
-LES is Chronically Constricted -"Bird-Beak" Results -Pressure in the Thorax is Higher -Body Starts to Swell Up |
|
|
What happens in a Hiatal Hernia? When does this typically occur?
|
-LES is pushed into the Thorax
-In a Lower Pressure Area -Tends to Stay Open |
|
|
What happens during GERD?
|
-Loss of Tone at the LES
-Chronically Open -Food Refluxes back into the Esophagus -Heartburn can result |
|
|
What forms the Gastric Reservoir?
|
Fundus and Corpus of the STomach
|
|
|
What happens to the Pressure of the Gastric Reservoir as it receives food. Why?
|
-Increases only Slightly
-Stomach Relaxes as it fills |
|
|
What could an increase in the pressure of the stomach cause?
|
Reflux
|
|
|
What are the 3 Reflexes that Change the Compliance of the Stomach?
|
-Receptive Relaxation
-Adaptive Relaxation -Feedback Rerelaxation |
|
|
What is Receptive Relaxation?
|
-Brief Relaxation during Chewing and Swallowing
-Happens before Food Arrives in the Stomach -Causes Relaxation of the Gastric Reservoir |
|
|
Describe how Receptive Relaxation occurs.
|
-Mechanoreceptors in the Mouth and Pharynx Induce Vaso-vagal reflexes
-Afferent Fibers - Go to the Vagal Center Efferent Fibers - NANC Inhibition - Results in Inhibition of Tone in the Stomach |
|
|
What is Adaptive Relxation?
|
-Activated by Receptors when Stomach is filled with Food
-Elicits Gastro-Gastric (Vaso-Vagal) Reflex -Afferent - Go to Vagal Center -Efferent - NANC Inhibition |
|
|
What is Feedback Rerelaxation?
|
-From Duodenum
-Afferents to Vagus Center -Same Efferents from Vagus Center -Relaxes Stomach |
|
|
What happens in Diabetic Neuropathy?
|
-Nerves Die
-Vagus to stomach can be lost -Lost Relaxation -Pressure goes up -Reflux |
|
|
How does all this Relaxation shit happen in the Gastric Reservoir?
|
-Vagal Fibers are activated
-Send NANC Inhibitory Fibers -Results in Inhibition of Tone in the Stomach |
|
|
What are the 2 Mechanisms of Gastric Emptying?
|
-Tonic Contractions of the Gastric Reservoir
-Peristaltic Waves moving over the Distal part of the Gastric Corpus |
|
|
What kind of Reflex is Gastric Emptying?
|
Short Loop
|
|
|
Where is the Gastric Pacemaker located?
|
-Middle of the Corpus
-In the Orad Corpus Gastric Wall |
|
|
What are the 3 Mechanisms of the Antral Pump?
|
-Phase of Propulsion
-Phase of Emptying -Phase of Retropulsion |
|
|
What is the "Sieving" Function of the Antral Pump? Explain.
|
-Phase of Retropulsion
-Final portion of Antrum COntracting -Pyloris is Closed -Larger Particles are Pushed Back -Tells Stomach to break them down further |
|
|
What is going on during the Phase of Emptying?
|
-Wave of Contractions
-Moves toward Pyloris -Emptying Liquids and Small Particle Suspensions into the Duodenum |
|
|
What is going on during the Phase of Propulsion?
|
-Rapid Flow of Liquids and Small Particles
-Contraction in the Mid-Antrum |
