Lecture 16 - Small Intestinal motility (Sanchez) Flashcards Preview

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Flashcards in Lecture 16 - Small Intestinal motility (Sanchez) Deck (13)
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1
Q

characteristics of longitudinal muscle

A
  • thin muscle coat
  • contraction shortens length, expands radius
  • few gap junctions
  • external Ca++ infux important in excitation contraction coupling
  • innervated and activated by motorneurons
2
Q

circular muscle

A
  • thick muscle coat
  • contraction increases length, shortens radius
  • innervated by excitatory and inhibitory motorneruons
  • activated by intersitial cells of Cajal
  • many gap junctions
  • intrcellular Ca++ release important for excitation contraction coupling
3
Q

slow waves =

A

basic electrical activity of small intestine

- rate decreases along SI

4
Q

what is the migrating motility complex (MMC)

A

the basic myoelectrical unit of the SI made up of 3 components:

  1. Phase 1 = comprised of only SW, no action potential. thus no contractions evident
  2. Phase 2 = intermittent AP with a variable pattern
  3. Phase 3 = AP occurs with every SW thus this phase has intense sustained contraction
5
Q

segmentation

A

isolated contractions that result in mixing of contents

6
Q

peristalsis

A

consists of aborally propagating rings of contraction that move contents some distance down the tract

7
Q
species differences in feeding patterns (essentially a prolonged phase II)
dog
pig
horse 
ruminants
A

dog - very affected
pig - variable
horse - kind of effected
rumiants - no feeding pattern

8
Q

what is the default muscular state of the small intestine?

A

muscular relaxation is the default state as the circulatory smooth muscle is under active control of the inhibitory motor neruons. this condition is called “physiological ileus”

9
Q

what is the most prominent nsympathetic (adrenergic) neurotransmitter?

A

NE - the effect is inhibitory

10
Q

where do parasympathetic efferents synapse? what transmitter do they use?

A

eneteric nervous system; Ach

11
Q

characteristics of alpha 2 adrenoreceptors

A

INHIBITS release of Ach from cholinergic neurons within myeneteric plexus

  • alpha 2 agonist: (decreases motility)
  • alpha 2 antagonist: (increases motility)
12
Q

prokinetics

A

increase motility

13
Q

what agents inherently decrease motility and are commonly used as sedatives and anaglesic agents?

A

alpha 2-adrenoreceptor AGONISTS and opoids

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