Lecture 16 - Small Intestinal motility (Sanchez) Flashcards Preview

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

characteristics of longitudinal muscle

- 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

circular muscle

- 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

slow waves =

basic electrical activity of small intestine
- rate decreases along SI

4

what is the migrating motility complex (MMC)

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

segmentation

isolated contractions that result in mixing of contents

6

peristalsis

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

7

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

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

8

what is the default muscular state of the small intestine?

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

what is the most prominent nsympathetic (adrenergic) neurotransmitter?

NE - the effect is inhibitory

10

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

eneteric nervous system; Ach

11

characteristics of alpha 2 adrenoreceptors

INHIBITS release of Ach from cholinergic neurons within myeneteric plexus
- alpha 2 agonist: (decreases motility)
- alpha 2 antagonist: (increases motility)

12

prokinetics

increase motility

13

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

alpha 2-adrenoreceptor AGONISTS and opoids

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