swallowing, gastric emptying, and gastric motility Flashcards Preview

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Flashcards in swallowing, gastric emptying, and gastric motility Deck (29):
1

phases of swallowing

oral
pharyngeal
esophogeal

2

oral phase

voluntary
bolus moved by tongue to pharynx

3

pharyngeal phase

-involuntary
-initiated in response to pressure receptors in pharynx
-directs bolus into esophagus via relaxed UES
-respiration inhibited

4

esophageal phase

involuntary
-primary peristaltic wave: bolus from UES via peristalsis through LES to stomach
-secondary peristalsis- initiated by distension, occurs only if primary wave not sufficient
-both primary and secondary peristalsis modulated by CNS and ENS reflexes

5

LES control

resting tone set my intrinsic myogenic properties and cholinergic regulation
relaxation due to vagus, VIP, and NO
swallowing and/or esophageal distention decrease LES tone

6

achalasia

absence of relaxation
dilated esophagus proximal to LES
LES fails to relax
peristalsis impaired in distal 2/3s
unknown mechanism, possibly loss of VIP and/or NO
no treatment

7

GERD

-LES low resting tone, allows reflux
-low bicarb in salivia

8

Orad region

fundus and proximal body
receives and stores food

9

caudad region

distal body and antrum
mixing and propelling

10

LES and cardia

prevention of reflux
entry of food
regulation of belching
mucus
bicarb

11

fundus and body

resevoir
tonic force during emptying
-H
-IF
mucus
-bicarb
-pepsinogens
lipase

12

antrum and pylorus

mixing
grinding
sieving
regulation of emptying
mucus
bicarb

13

increase contractility

distension
fluidity of chyme (increased fluidity increases emptying)
Ach
substance P
gastrin

14

inhibitory to gastric emptying

distension in duodenum
presence of FAs, monoglycerides, acidic pH, hypertonicity, AA, and/or peptides in duodenum
CCK
secretin
GIP
NE

15

gastric mixing

propulsion
grinding
retropulsion
trituation- reduction of particle size, must be <2mm to leave stomach

16

relative rates of gastric emptying

liquid > carbohydrates > protein > fat
isotonic fluid >hypertonic or hypotonic

17

pyloric sphincter control

constriction: CCK, secretin, gastrin, sympathetics
relaxation: parasympathetics, vagus, Ach constricts, VIP relaxes

18

migrating myoelectric complex stomach

fasting state, every 75-120min, starts 2 hours after meal
burst of strong antral electrical activity for 5-10minutes with relaxation of pylorus
'cleans' tract from stomach thru SI

19

Emesis

stimulated by
-gastric and duodenal distension or irritants
-dizziness, inner ear dysfunction, motion sickness, pregnancy
-drugs
-GU injury
-emetics (tigger either chemoreceptors or gastric/duodenal receptors)

20

segementation

postprandial period- alternating contractions of circular smooth m
slow process of propulsion and retropulsion:
- allows for digestion time
-mixes
maximizes contact w/mucosal layer for absorption

21

peristalsis

postprandial- coordinated propulsive contractions of circular smooth m
relaxation in front of bolus (VIP and NO)
contraction behind bolus (Ach and supstance P)

22

migrating myoelectric complex

new wave begins in stomach once wave had passed distal ileum
3 phases: quiescence, small disorganized contractions, strong propagating contractions (5-10min)
repeats every 75-120 min during fasting
correlated w/high levels of motilin

23

slow waves

duodenum highest rate 11-13/min
jejunum 10-11/min
ileum 8-9/min

24

colic motility

haustrations
loing duration contractions
mass movements

25

haustrations

short duration contractions about 8 seconds
circular mixing contractions

26

long duration contractions

-taeniae coli
-mixing contractions, may propagate short distance in either direction
-antipropulsive movements in proximal colin reain chyme for absorption

27

mass movements

high amplitude propagating contractions
sweep length of colon
1-3/day

28

regulation of colonic motility

primarily neural regulation (ENS, PNS, SNS)
local reflexes- colonic distension (contraction behind, and relaxation in front of bolus)
long range reflex- gastric distension

29

defecation reflex

requires extrinsic neural input
higher CNS and spinal cord coordination via pelvic nn
rectosphincter reflex (VIP and NO)