Esophageal Motility and Slow Waves Flashcards Preview

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Flashcards in Esophageal Motility and Slow Waves Deck (79)
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1

2 Types of visceral smooth muscle contraction

phasic and tonic contractions

2

phasic contraction

rhythmic contractions and relaxations in seconds (single-unit of SM)

3

tonic contractions

sustained contraction lasting minutes to hours (multi-unit SM or sphincters)

4

Which contraction occurs depends on

myogenic properties of the SM (single unit vs multi), NOT neuronal/hormonal control

5

The strength of the contraction depends on

neuronal/hormonal control

6

Tone

baseline tension maintained between phasic contractions above 0

7

What allows for single unit SM to have coordinated contractions?

GAP junctions

8

What is the effect of ACh on visceral SM?

Contraction

9

ACh binds what receptor to cause visceral SM contraction

Muscarinic

10

Peristalsis is an example of what type of contraction?

phasic contractions

11

All GI smooth muscle has basal tone except

smooth muscle of the lower 2/3 of the esophageal body

12

striated muscle of the esophageal body contracts when

excitatory NT is released

13

striated muscle of the esophageal body relaxes when

excitatory NT is NOT released

14

visceral smooth muscle contracts when

excitatory NT is released

15

visceral smooth muscle relaxes when

inhibitory NT is released

16

3 functional parts of the esophagus

Upper esophagus sphincter (UES), Body, Lower esophageal sphincter (LES)

17

UES

junction of pharynx and esophageal body; striated muscle, normally closed (vagal LMNs)

18

Body

located between 2 sphincters, upper 1/3 is striated, lower 2/3 is smooth muscle, no slow waves or basal tone

19

LES

junction of esophagus and stomach, under intra-thoracic and intra-abdominal pressure; multi-unit circular smooth muscle, high tone, modulated by inhibitory and excitatory neurons

20

Contraction

increased intensity of tonic contractions

21

Relaxation

decreased intensity of tonic or phasic contractions

22

Oral Stage of deglutition

VOLUNTARY; inhibits respiration for 2 sec

23

Pharyngeal stage of deglutition

INVOLUTARY; bolus activates afferent sensory neurons in oropharynx and PRIMARY peristaltic contractions propel food through UES and into upper esophageal body

24

Esophageal stage of deglutition

INVOLUNTARY; PRIMARY peristaltic contraction propels food through lower esophageal sphincter and into stomach

25

What nerve innervates the esophagus?

Vagus

26

Striated muscle of the UES and esophageal body is innervated

DIRECTLY by the vagal LMNs, which form motor endplates

27

Vagal LMN endplates release ______ that binds striated muscle receptors to cause contraction

ACh binds Nicotinic muscle receptors on UES and upper 1/3 esophageal body to cause contraction

28

Smooth muscle of the esophagus is innervated

INDIRECTLY by vagal preganglionic neurons synapsing on myenteric neurons (inhibitory and excitatory pathways)

29

2 types of esophageal peristalsis

primary and secondary

30

Primary esophageal peristalsis

preceded by pharyngeal peristalsis, follows a swallow, LONG parasympathetic neural reflex