Lecture #27 - Motility Flashcards
What’re the four basic functions of motility in the GI tract and what two things do the first two involve?
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What kind of muscle is in the GI tract? What’re the two exceptions?
What’s cool about the GI smooth muscle? (it’s spon____)
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Basis of spontaneous activity:
- Slow wave or BER = ____ ____ ____
- S____ variations in membrane potential
- Produce a____ p_____
- results in _____
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Regulation of motility:
How?
-In order to regulate the motility, you usually either change the frequency of depolarisations or depolarise for longer. Here, you can’t change the frequency because BER determines the frequency of contractions and it’s spontaneous (hormones or nervous can’t change that).
But you can alter the strength of contraction by generating more AP i.e. generating more force thereby regulating motility. So what happens is that as neurotransmitters and hormones bind to receptor, can change the membrane potential of SM cell and this shifts the BER (slow waves) up/down (hyperpolarising/depolarising) and this will change how the cycle crosses the threshold. Look at graph on Slide 8
- What determines the type of motility that occurs?
- What are the two main motility patterns that occur?
- What does the ENS coordinate?
- This all depends on what loops? Explain them - yellow
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Feeding motility patterns in GI tract:
- Storage
- Mainly in what?-Relaxation of what? - Peristalsis
- Four places where it happens
- P____ - Segmentation
- Where?
- Mixing and exposure to what?
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Peristalsis:
- Contractions behind what? Relaxation where?
- Get food to move q____
- What kind of gradient is generated that allows food to move rapidly?
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Segmentation:
- Wikipedia says…..
- Doesn’t play large role in what?
- Mixes food with what?
- Mostly takes place in SI or LI?
- Unlike peristalsis, which predominates in the esophagus, segmentation contractions occur in the large intestine and small intestine, while predominating in the latter. While peristalsis involves one-way motion in the caudal direction, segmentation contractions move chyme in both directions, which allows greater mixing with the secretions of the intestines. Segmentation involves contractions of the circular muscles in the digestive tract, while peristalsis involves rhythmic contractions of the longitudinal muscles in the GI tract. Unlike peristalsis, segmentation actually can slow progression of chyme through the system.
Specific motility patterns - three of them, what are they? (really simple)
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Chewing
- Function - name three
- Control - what is the basic control and what three things are controlled by reflexes?
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Swallowing (deglutition)
- Function - two things
- Control - when is it voluntary and when not?
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Gastric motility:
- Fasting - Shrinks to s_____ v_____
- What other motility pattern takes place in the stomach during fasting? - Eating - delivery of food
- Series of motility patterns occur with what 4 things?
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Storage in the proximal stomach:
- What is the reaction called to food moving into stomach and increasing the volume (this needs to happen to allow the pressure to stay the same)?
- What is that thing in 1 initiated by?
- What other thing also relaxes and why?
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Peristalsis:
- Peristaltic waves - initiated where, how many a minute and spread to where?
- How long is the gentle activity?
- How long is the intense activity and what is it stimulated by? What hormone does the presence of these aa’ release? What does it do?
- So peristalsis does propulsion and retropulsion (combined with the pyloric sphincter). So how does this work and what is it not? I.e. what kind of motility pattern doesn’t occur in stomach?
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Small intestine motility:
- What is the overall function of small intestine? (2)
- What are the three functions of motility here?
- What are the two motility patterns and what’s the main one?
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