Swallowing, gastric emptying and intestinal motility Flashcards
(109 cards)
1
Q
Where are the Touch R for swallowing
A
near opening of pharynx
2
Q
Where is the integration center for swallowing
A
medulla oblongata (lower pons)
3
Q
What n control the upper esophagus and pharynx
A
cranial nn
4
Q
what n innervates the lower esophagus
A
vagus n
5
Q
what mm are inn by the cranial and vagus nn
A
pharyngeal and esophageal striated and smooth m
6
Q
What are the three phases of swallowing
A
oral phase
pharyngeal phase
esophageal phase
7
Q
Which phase is voluntary in swallowing
A
oral. tongue to pharynx
8
Q
describe the pharyngeal phase of swallowing
A
involuntary, reflex-respiration inhibited- epiglottis blocks trachea
soft palate blocks nasopharynx entry-way
pressure R in pharynx trigger
bolus directed into esophagus via relaxed upper esophageal sphincter
9
Q
describe the esophageal phase of swallowing
A
involuntary
bolus from upper esophageal sphincter via peristalsis through lower esophageal sphincter–> stomach
10
Q
What are the prtective effects of the upper esophageal sphincter
A
protect airway from swallowed material
protect airway from gastric reflux
11
Q
What are the protective effects of the lower esophageal sphincter
A
protects esophagus from gastric reflux
12
Q
During what phases of swallowing is the larynx elevated
A
end of oral all of pharyngeal and begining of esophageal
13
Q
What initiates esophageal phase
A
peristaltic wave initiated by swallowing center.
secondary peristalsis is initiated by distention (only if primary wave not sufficient)
14
Q
What nn are involved with esophageal phase
A
input from esophageal fibers to CNS and ENS modulate primary and secondary esophageal peristalsis
15
Q
Swallowing induces relaxation of lower esophageal sphincter and?
A
proximal stomach
16
Q
How do sphincters manage antegrade and retrograde movement
A
high resting pressure
17
Q
Differentiate proximal stimuli and distal for sphincters
A
proximal cause relaxation, distal cause contraction
18
Q
What needs to be coordinated for unidirectional movement of GI
A
smooth m contractions
neural stimulation
humoral stimulation
19
Q
Describe structure upper esophageal sphincter
A
striated m
regulated by cranial nn
highest resting pressure
closed during inspiration
20
Q
desribe structure lower esophageal sphincter
A
smooth muscle regulated by cholinergic stimuli and vagus n
21
Q
What is the primary function of lower esophageal sphincter
A
allows coordinated movement
prevents reflux of gastric contents into esophagus
22
Q
Describe the LES resting tone
A
Intrinsic myogenic properties
cholinergic regulation
23
Q
Describe LES relaxation
A
intrinsic smooth m
vagus n
occurs after UES returns to high resting pressure
24
Q
What inhibits the LES relaxation
A
VIP and NO
25
what allows for entry of food into the stomach
the distention or swallowing decreases LES pressure and makes it less than intragastric pressure
26
What is dysphagia
difficulty swallowing
27
What are some structural abnormalities to dysphagia
tongue
esophageal or pharyngeal wall out pouching
stomach protruding above diaphragm (hiatal hernia)
esophageal tumors
28
What are some functional abnormalities that can cause dysphagia
neurological defects, PD, Myasthenia Gravis
| muscular layer defect
29
What are Tx for dysphagia
surgery- cut tight muscle
remove obstructing tumors
increase salivary function
30
What is Achlasia
special form of dysphagia from a dilated esophagus proximal to LES so that it fails to relax, peristalsis is impaired
31
What is the Tx for achlasia
wiring defect cannot be corrected
| symptomatic relief to reduce LES pressure, gravity
32
What is GERD
LES resting pressure prevents reflux from esophagus usually but with GERD reduce LES resting pressure
33
What is it that refluxes in GERD, and what can it cause
gastric juice, causing esophagitis or erosion of esophageal mucosa
34
What is Tx for GERD
control gastric acid secretion
less R of esophageal mucus
Less HCO3 secretion from saliva
commonest disease
35
Where is the orad region of the stomach
fundus and proximal body
| receives and stores food
36
Where is the caudad region
distal body and antrum
| mixing and propeling
37
What is secreted in gastric lumen near LES/cardia
mucus and HCO3
38
What is secreted in gastric lumen near funds/body
H+, IF, mucus, HCO3, pepsinogens, lipase
39
What is secreted in gastric lumen near antrum and pylorus
mucus and HCO3
40
What is receptive relaxation
LES and stomach relax, vagovagal reflex of VIP, pressure in stomach does not increase with increased V
41
What can cause a rapid pressure increase in the stomach
disruption of vagus n- vagotomy
42
What is gastric accommodation
relaxation in response to gastric filling, dilate fundus
| allows increased volume to keep P consistent
43
What n controls gastric accommodation
vagus and ENS
44
Where does gastric mixing happen
antrum
45
what occurs during gastric mixing
increased gastric contractility
| the stomach contents of chyme is a positive stimuli for contractility
46
What substances can increase gastric mixing
ENS: Ach and Substance P
| Gastrin
47
What stimuli are inhibitory to gastric emptying
duodenum contents: fatty acids, monoglycerides, acidic pH, volume/distention, hypertonicity, AA and peptides
48
What hormones can inhibit gastric emptying
CCK, secretin, GIP
49
what neural control is there over gastric emptying
intrinsic and extrinsic
50
Increased fluidity of stomach causes more or less contraction
more motility
51
Intense pain has what effect on stomach
inhibits motility and emptying
52
emotion has what effect on stomach
stimulates or inhibits motility and emptying
53
Where is the pacemaker zone of stomach and role
in body of stomach, sets rate of gastric peristalsis (3-5 slow waves/min)
54
What determines contraction force of stomach
degree od depolarization
| duration of membrane depolarization
55
What affect do gastrin and Ach have on gastric contractions
increase amplitude and duration
| increase contractility
56
what affect does norepinephrine have on gastric contractions
decreases contractility
57
What are the 3 mechanisms of gastric mixing
propulsion
grinding
retropulsion
58
what is stomach trituration
reduction of solid particle size
has to me less than 2 mm
emptying does not happen until solids are broken down
59
what molecules are emptied from stomach in order of greatest amount to least
liquid, carbs, protein, fat
60
Is gastric emptying carrying isotonic, hypertonic or hypotonic fluid
isotonic usually
61
What R are in the duodenum
pH, osmole, FA/monoglycerides, aa/peptides
62
what stimulus from duodenum slows gastric emptying
byproducts of fat and protein digestion
hypertonic chyme
<3.5 pH
63
Why is coordination of stomach with duodenum important
so chyme can be effectively processed by duodenum and not regurgitated
64
What are the neural and humoral events in duodenum that inhibit gastric emptying
relaxation fundus
inhibit antral contraction
stimulate pyloric contraction
65
What stimulates secretin release and its effects
acidic chyme
| results in dec contractility of antrum, increased constriction of pylorus
66
What simtulates CCK and GIP and what are the effects
FA and monoglycerides
results in relaxation of gastric smooth m
increased constriction of pylorus
67
What stimulates gastrin and what are the effects
purely hormonal from peptides and aa
causes increased contractility in antrum
constriction of pylorus
68
What hormones cause increased constriciton of pyloric sphincter
CCK, GIP, secretin and gastrin
69
Describe the neural regulation of pyloric sphincter
SAN-->constriction
PAN-->vagus
constriction is Ach, relaxation is VIP
70
Approx when does the fasting state occur in regard to a meal
2 hours after a meal,
| migrating myoelectri complex
71
What is Emesis
reflex vomiting, integration in medulla
72
What stimulates vomiting
gastric and duodenal distention and irritants
dizziness, inner ear dysfunction, moiton sickness
drugs
genitourinary injury
emetics: chem that cause vomiting
73
What is an emetic and where is the response center
ipecac- gastric/duodenal R that rigger chemo receptor in 4th ventricle of brain
74
What occurs in the vomit reflex
```
reverse peristalsis from SI->pylorus
pyloric sphincter relaxes and stomach
abs contract
pylorus and antrum contract
LES releaxes, gastric contents enter, UES relaxes
```
75
What are the 3 types of SI mobility
segmentation(mixing)
peristalsis(propulsion)
migrating myoelectric complex(sweeping of undigested contents during fasting state
76
What is the postprandial period of segmentation
part of segmentation when there are alternating contractions of circular sm m
77
Why is segmentation a slow process of propulsion and retropulsion
time for digestion and absorption
mixes chyme with digestive secretions
maximizes contact with mucosal layer
78
What is the postprandial phase of peristalsis
coordinated propulsive contractions of circular sm m
79
What causes the releaxation in front of bolus and contraction behind during perstalsis
relaxation in front: VIP and NO
| contraction: ACh and Substance P
80
Describe the migrating myoelectric complex
new wave starts in stomach once previous wave passes distal ileum to move undigested material
81
What are the 3 phases of migrating myoelectric complex
quiescence, small disorganized contractions, strong propagating contractions
82
circulating motilin usually correlates to what
migrating myoelectric complex
83
What protective mech is the migrating myoelectric complex
prevent backflow of bacteria from colon to ileum
84
What part of SI has highest electrical rhythym
duodenum
85
What increases the burst of APs on slow waves
hormones, ENS, PAN and SAN via ENS
86
The contraction behind and relaxation in front of bolus is intrinsic or extrinsic
intrinsic ENS
87
What is intestinointestinal reflex
distention in one segment, relaxation in the rest of SI
88
What coordinates tone of ileocecal sphincter
normally contracted
| ENS reflexes, long range extrinsic ENS and hormones
89
distention and ileum causes what in ileocecal sphincter? distension in ascending colon?
ileum->relaxation
| ascending colon->constriction
90
What is the gastroleal reflex
increased gastric activity increases ileal motility and releaxation of the ileocecal sphincter
91
what is the purpose of the ileocecal sphincter
control rate of chyme entering colon so can absorb water and salts
92
What are the 3 primary types of colonic motility
Haustrations
Long duration contractions
mass movements
93
describe haustrations of colon
short duraction contrations, circular m-->mixing
94
describe long duration contractions
taeniae coli, mixing contractions that may cause propagation short distances in either direction
(not in proximal colon so can retain chyme)
95
describe mass movements of colon
high amplitude propagating contractions, sweep length of colon
1-3/day
high variability in colonic motility per person
96
Describe the control of colonic motility
primarily neural regulation via ENS, PNS, SNS via intrinsic control and extrinsic modulation
local reflexes from colonic distention
long range reflex from gastric distention- gastrocolic reflex
97
What is the effect of PAN on colon
vagus via ENS increases mixing in proximal colon
| pelvic splanchnic nn via ENS cause increased contractions and propulsive movements in distal colon
98
What is the effect of SAN on colon
inhibits motility
| postganglionics via abdominal sympathetic ganglia
99
Describe the internal anal sphincter
smooth m
involuntary control
majority of tone
100
describe the external anal sphincter
striated m
| voluntary and involuntary control
101
defectaiton requires what stimulus
extrinsix neural input-> higher CNS
102
What results from distention in rectum
relaxation IAS reflex
rectosphincteric reflex: VIP and NO
reflex to constrict EAS
103
Is defectaion voluntary or no
coordinated volunatary and involuntary events
voluntary relaxation of EAS
contraction ABs
relaxation pelvic mm
104
What is Hirschsprungs disease
```
congenital megacolon
fialure of ENS development
impairs motility
Aganaglionic segment
rectosphincteric reflex impaired
```
105
Tx for hirschsprungs
surgical excision of diseased or aganglionic segment
106
Irritable bowel syndrome or disease is what
group of inflammatory conditions of colon and SI
107
What causes IBS/IBD
visceral hypersensitivity due to sensitization of afferent neural pathways
respond abnoramaly to stimuli
idiopathic, distention, inflammation, GI infections
partial dysmotility
108
What are the major types of IBD
Crohn's disease and ulcerative colitis
109
How do you Dx IBD
assessment of inflammatory markers in stool then colonoscopy with biopsy of pathological lesions
