Gastrointestinal Motility Flashcards
1
Q
Function of GI tract
A
Propulsion, Accommodation, Propulsion, Retropulsion, Storage, Functional barrier,
2
Q
3 Basic units of GIT control
A
Interstitial pacemaker cells,
Enteric nervous system,
Extrinsic innervations
3
Q
Which cells can spontaneously depolarise
A
Interstitial cells of Cajal
4
Q
How are interstitial cells of cajal connected
A
Specialised gap junctions
5
Q
Are the spontaneous waves of depolarisation from interstitial cells of cajal fast or slow
A
Slow
6
Q
Where is the pacemaker region in the stomach
A
Corpus
7
Q
Where does electrical activity from the pacemaker region travel too
A
Pylorus
8
Q
Where is frequency of electrical waves from the pacemaker region higher
A
Greater curvature
9
Q
How do interstitial cells of cajal cause muscle contractions
A
Produce slow wave of depolarisation -> wave goes from ICC to muscle -> cell depolarised -> ca2+ channels open -> action potential -> muscle contracts
10
Q
Where are electrodes placed for an electrogastrogram
A
Upper abdomen
11
Q
What is a myogenic contraction
A
Spontaneous muscle movements in stomach
12
Q
What modulated myogenic contraction in the stomach
A
Enteric nervous system
13
Q
What does the Myenteric plexus primarily control
A
Motility
14
Q
What does the submucosal plexus primarily control
A
Fluid exchange
15
Q
What does the enteric nervous system control
A
GI motility,
Local blood flow,
Transmucosal movement of fluids
16
Q
What does the enteric nervous system interact with
A
Gut endocrine system,
Gut immune system,
CNS
17
Q
What does the enteric nervous system contain
A
Steppe sorry elements,
Interneurones,
Motor neurones
18
Q
What is the enteric nervous system modulated by
A
Extrinsic nerves,
Hormones
19
Q
Gastrointestinal hormones of the stomach
A
Ghrelin,
Gastrin
20
Q
Gastrointestinal hormones of the duodenum
A
Cholecystokinin,
Secretin,
GIP,
Motilin
21
Q
Gastrointestinal hormones of the pancreas
A
Insulin,
Glucagon,
Pancreatic polypeptide,
Amylin
22
Q
Gastrointestinal hormones of the small intestine and colon
A
GLP-1,
GLP-2,
Oxyntomodulin,
PYY3-36
23
Q
What does ghrelin cause
A
Hunger,
Growth hormone release
24
Q
What does gastric cause
A
Acid secretion
25
What does cholecystokinin cause
Gall bladder contraction,
Gastrointestinal motility,
Pancreatic exocrine secretion
26
What does secretin cause
Pancreatic exocrine secretion
27
What does GIP cause
Incretin activity
28
What does motilin cause
Gastrointestinal motility
29
What do insulin and glucagon cause
Glucose homeostasis
30
What does pancreatic polypeptide cause
Gastric motility,
| Satiation
31
What does amylin cause
Glucose homeostasis,
| Gastric motility
32
What does GLP1 cause
Incretin activity,
| Satiation
33
What does GLP2 cause
GI motility,
| GI growth
34
What does oxyntomodulin cause
Satiation,
| Acid secretion
35
What does PYY3-36 cause
Satiation
36
How does stress increase contractile movements of the colon
Increases contractile state
37
Dominant control system in the eosophagus
CNS
38
Dominant control systems in the stomach
Myogenic,
ENS,
CNS
39
Dominant control systems in the small intestine
ENS
40
Dominant control systems in the colon
ENS,
| Myogenic
41
Dominant control systems in the anus
ENS,
| CNS
42
How many phases are there in hunger
3
43
How often does each phase of the migrating motor complex occur
90-120 mins
44
Where does vagus dependent migrating motor complex originate
Stomach
45
Where does vagus independent migrating motor complex originate
Small intestine
46
When does the migrating motor complex occur
During hunger
47
Migrating motor complex functions
Clear undigested material,
Prevent bacteria overgrowth,
Hunger,
48
Which phase of the migrating motor complex is hunger highest in
Gastric phase 3
49
3 phases of digestion
Cephalic phase,
Gastric phase,
Intestinal phase
50
Parts of cephalic phase
Thought,
Sight,
Smell,
Taste,
51
How does the cephalic phase prepare the GI tract
```
MMCs abolished,
Saliva secretion,
Gastric acid secretion,
Pancreatic secretion,
Gastric secretion
```
52
Parts of gastric phase
Satiation,
Early digestion,
Gastric emptying
53
What triggers the gastric phase of digestion
Mechanical effect
54
Parts of intestinal phase of migration
Feedback,
| Satiation
55
What triggers the intestinal phase of digestion
Chemoreceptor activation in small bowel
56
Which part of the CNS controls the striated muscle and transition zone of the eosophagus
Nucleus ambiguus
57
Which part of the CNS controls the smooth muscle and transition zone
Dorsal motor nucleus
58
When does the primary peristaltic wave occur
Swallowing - when bonus enter eosophagus
59
What type of muscle cod involved in the primary peristaltic wave
Striated
60
When does the secondary peristaltic wave occur
When stretch receptors activated,
| Local reflex
61
Function of second peristaltic wave
Forces food into stomach,
| Backup to primary peristaltic wave
62
What happens to the longitudinal muscles in the oesophagus to aid movement into stomach
Shorten
63
How is reflux into the oesophagus prevented
Closure of LES,
| tightening of crural fibres
64
Functions of the proximal stomach
Receptive relaxation,
| Adaptive relaxation
65
What kind of reflex is receptive relaxation
Vago vagal
66
What type of reflex is adaptive relaxation
Enteric reflex
67
What nt triggers receptive relaxation
CCK
68
What nt triggers adaptive relaxation
NO - released from ENS
69
What is accommodation
Expansion in stomach size without significant increase in intragastric pressure
70
What causes burping
Transient lower eosophageal sphincter relaxations
71
Purpose of burping
Reduce pressure in stomach,
| Avoid early satiety
72
Which hormone plays a major role in controlling DMV neuronal firing rate, and how
GABA,
Regulates vagal efferent outflow,
Modulates gastric tone/motility
73
How do vagal sensory neurones reach the PVN and DMV
enter CNS -> transmit to NTS -> NTS neurones integrate to PVN and DMV
74
Vagi vagal reflexes during a meal
TLESRs,
Accommodation,
MMC activity abolished
75
Functions of the distal stomach
```
Propulsion,
Retropulsion,
Grinding,
Sieving,
Mixing
```
76
How does the grind food into fragments
Contraction
77
How does the stomach liquefy food
Gastric acid digestion,
| Natural contractions
78
How large are particles emptied into the duodenum
1-2mm
79
3 phases of sieving
Propulsion,
Emptying,
Retropulsion
80
Propulsion stage of sieving
Lipids and suspended particles flow rapidly,
| Large particle flow delayed
81
Emptying stage of sieving
Liquids and small particles emptied,
| Large particles remain in bulge of terminal antrum
82
Retropulsion stage of sieving
Retropulsion of large particles
83
Why is there a lag phase for the emptying of large particles
Need more grinding
84
How long is the lag phase for large particles
20-30 mins
85
How are liquids emptied from the stomach
Quickly,
| Exponentially
86
How is viscous chyme emptied from the stomach
Linear
87
Which is emptied first, liquids or viscous chyme
Liquids
88
Do large or small volumes empty faster
Large
89
Why does stomach emptying speed depend on nutrient density
To avoid overloading intestine
90
How is rate of stomach emptying regulated
Feedback from small intestine
91
What does feedback regulation of gastric emptying maintain
Constant flow of nutrients into intestine
92
2 parts of feedback regulation of gastric emptying
Duodenal and jejunal brake,
| Ileal brake
93
Duodenal and jejenal brake
Nutrients enter intestine -> CCK released -> vagal afferents activated -> gastric emptying slowed
94
How does activation of vagal efferent in the duodenal and jejenal brake slow gastric emptying
Reduces opening of pyloric sphincter,
Reduces contraction of corpus antrum,
Enhances relaxation of fundus
95
Ileal brake
Fats reach ileum -> mediators slow gastric emptying and induce satiety
96
Why does fats reaching the ileum stimulate the Ileal brake
Fats usually absorbed in duodenum
97
What are the mediators of the Ileal brake
Peptide YY,
| Glucagon like peptide 1
98
What is the primary source of feedback signalling for physiological regulation
Enteroendocrine cells
99
What do nutrient receptors do when activated
Release nutrients
100
What can poor feedback control lead to
Obesity
101
What does incomplete gastric accommodation cause
Early satiety,
| Nausea
102
What does dysrhythmia cause
Nausea
103
What causes gastroesophageal reflux
Failure to clear acid,
| Dysfunctional lower oesophageal sphincter
104
What causes propulsion
Contraction at oral end and relaxation at anal end of bolus
105
Is the ascending wave of peristalsis excitatory or inhibitory
Excitatory
106
Is the descending wave of peristalsis excitatory or inhibitory
Inhibitory
107
Where does the ascending and descending waves of peristalsis go to
Muscle
108
Which nt is used in the ascending wave of peristalsis
Acetylcholine
109
Which nt is used in the descending wave of peristalsis
Nitric oxide
110
How are enteric reflexes chemically activated
Substances from endocrine cells,
Nutrients,
Low pH
111
How are enteric reflexes mechanically activated
Mucosal deformation,
| Stretch
112
What do enteric sensory nerves respond to
Mechanical and chemical intraluminal signals
113
What do enteric sensory nerves activate via interneurones
Motor neurones, causes peristaltic reflex
114
What does the peristaltic reflex modulate
Immune systems
Vascular systems
Muscular systems
Epithelial transport systems,
115
What speed is transport in the ascending colon
Slow
116
What speed is transport in the transverse colon
Fast
117
What speed is transport in the descending colon
Slow
118
What occurs in the ascending colon
Mixing,
Absorption,
Fermentation,
119
What occurs in the transverse colon
Absorption
120
What occurs in the descending colon
Storage
121
What is the purpose of haustra
Increase surface area
122
What is formed when the circular muscle relaxes
Haustra
123
What is formed when the circular muscle contracts
Semilunar fold
124
What are taenia
Thick bands of longitudinal muscle in the colon
125
Which direction do taenia contract in
Both
126
What do taenia do
Facilitate mixing and absorption of contents by contraction in either direction
127
Movements of the ascending colon
Propulsion,
Retropulsion,
Segmentation
128
What is the purpose of segmentation movements in the ascending colon
Mixes content,
| Increases exposure to mucosa
129
How is the type of movement in the ascending colon decided
Interstitial cells of cajal,
Local mediators,
Local environment
130
What influences luminal content
```
Food,
Drink,
Contaminants,
Microorganisms,
Microbial products,
Enzymatic breakdown of molecules,
Chemical breakdown of molecules,
Pharmaceuticals
```
131
How does mass movement occur in the colon
Constrictive ring occurs in portion of ascending colon -> 20cm of colon distal to constrictive ring contract as unit ->fecal matter propelled forward -> mass reaches rectum -> desire for defecation
132
How does rectal to anal movement occur
Contents distend rectum,
Pressure in rectum increases,
Internal anal sphincter relaxes,
External anal sphincter contracts,
133
How is defecation prevented
Internal rectal sphincter tone,
Puborectslis tone,
Acute anorectal angle mechanical effects
134
How is defecation initiated
Puborectalis relaxes,
External anal sphincter relaxes,
Valsalva manoeuvre increases intraabdominal pressure
135
How does defecation occur
Sphincter relaxation,
| Rectal propulsive contractions
136
What regulates peristalsis and intestinal movements
ENS,
| pacemaker cells
137
What Modular’s peristalsis and intestinal movements
Hormones,
| Extrinsic nerves
138
What causes pseudo obstruction
Failure of part of intestine,
| Drugs
