Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

metabolism > gut motility > Flashcards

gut motility Flashcards

1
Q

what are the types of cells found in the wall of the GI tract?

A

interstitial cells of cajal
smooth muscle cells
enteric neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what do ICCs do?

A

spontaneously generate electrical slow waves –> phasic muscle contractions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

how are the electrical waves of ICCs transmitted through smooth muscle

A

gap junctions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the advantage of smooth muscle being arranged as a functional syncytium?

A

allows waves to spread over large distances

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are the two plexuses of the GI system and what do they control?

A

Myenteric plexus – controls movement of the gut

Submucosal plexus – controls secretion, absorption and mucosal function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what does the ENS control?

A

GI motility, local blood flow and trans mucosal movement of fluids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what neurones does the ENS contain?

A

sensory
interneurons
motor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what modulates the ENS?

A

extrinsic nerves

hormones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

explain the intrinsic innervation of the gut

A

parasympathetic - vagus and pelvic nerves

sympathetic - prevertebral ganglia (greater splanchnic nerve, lumbar colonic nerve, hypogastric)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

describe which system controls each part of the GI tract?

A 
oesophagus - CNS
stomach - myogenic, ENS and CNS
small intestine - ENS
large intestine - ENS and myogenic
rectum and anus - ENS and CNS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the migrating motor complex?

A

large contraction every 90-120 minutes which occurs during hunger

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

where does the MMC originate?

A

stomach - vagus dependent

small intestine - vagus independent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are the three phases of the MMC?

A

Phase I + II: build-up of irregular contractions

Phase III: high amplitude, big contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the function of the MMC?

A

clears undigested material
prevents bacterial growth
gives sensation of hunger

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are the three phases of food intake and when do they occur?

A

cephalic - prepares GI tract for food.

gastric - when food enters the stomach

intestinal - when food has been digested

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what occurs in the cephalic phase

A

MMCs abolished. saliva, gastric acid, pancreatic acid secreted.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the gastric phase responsible for and what triggers it?

A

satiation, early digestion, gastric emptying

triggered by mechanical effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what triggers the intestinal phase and what occurs in it?

A

triggered by chemoreceptors in the small bowel

signals to stomach to stop eating - decreases appetite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

explain how the primary peristaltic wave occurs?

A

when bolus enters the oesophagus it hits the striated muscle

triggers vagus nerve –> primary peristaltic wave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

when does a secondary peristaltic wave occur in the oesophagus?

A

when the bolus moves down and gets stuck, triggering stretch receptors which trigger the ENS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

alongside peristalsis of the oesophagus, how is food movement into the stomach aided?

A

shortening of the longitudinal muscle

22
Q

what is the proximal area of the proximal area of the stomach?

A

funds and body

23
Q

what is receptive relaxation?

A

reflex in which the fundus relaxes to accommodate food triggered by the vago-vagal reflex

24
Q

what id adaptive relaxation?

A

the reflex which reinforces the reflective relaxation reflex. inhibitory NTS (NO) is released from the ENS so stomach dilates to accommodate food

25
Q

why may pressure build up in the stomach?

A

gas bubble forming from swallowing air

26
Q

how is pressure build up in the stomach relieved?

A 
increased pressure picked up by the stretch receptors
signals to vagus
causes TLOSRs
Burp reduces pressure inside stomach
Avoids early satiety
27
Q

which has a thicker wall - distal or proximal stomach?

A

proximal

28
Q

what are the 3 phases of propelling food into the duodenum?

A

Phase 1: propulsion
Phase 2: emptying
Phase 3: Retropulsion - large particles are sent back into the antrum

29
Q

why is gastric emptying of liquids exponential?

A

no solids to grind or liquefy - no lag time

30
Q

how does the volume of liquid affect the gastric emptying time?

A

larger volume = emptied faster

31
Q

why do large solid particles suffer a lag phase?

A

need sufficient grinding first

32
Q

what does the rate of gastric emptying depend on?

A

physical properties
neuronal and hormonal feedback
nutritional content

33
Q

explain the duodenal and jejunal brake?

A

duodenum detects nutrients, osmolality and HCl levels

CCK hormone is released to slow gastric emptying when too many nutrients enter the duodenum

vagal afferents signal the motor nuclei which signal vagal efferents to reduce opening of pyloric sphincter, reduce contractions in antrum and enhance relaxation

34
Q

explain the ileal brake

A

Fats usually digested and absorbed in the duodenum
Fats reach ileum
Feedback slows gastric emptying and induces satiety

35
Q

what is the ileal brake mediated by?

A

peptide YY, Glucagon-like peptide-1, oxyntomodulin

36
Q

name some of the GI conditions associated with motility

A

Gastro-oesophageal reflux: failure to clear acid/dysfunctional lower oesophageal sphincter.

Early satiety/nausea: incomplete gastric accommodation.
Neuropathy: diabetes
Dysrhythmia: nausea (gastroparesis)
Obesity: poor feedback control.

37
Q

what kind of receptors do the enteric sensory neurons contain?

A

mechanical and chemical sensitive receptors

38
Q

what are the mechanical and chemical stimuli of peristalsis?

A

Mechanical stimuli – stretch, mucosal deformation

Chemical stimuli – substances from endocrine cells (e.g. 5-HT), nutrients and low pH

39
Q

what do the sensory neurons of the GI tract do?

A

detect intraluminal stimuli

initiate peristalsis, plus increased secretion & vascular flow

40
Q

how is information from sensory neurons transmitted to motor neurons?

A

Via interneurons

ACh - secreted by excitatory nerves to the ascending wave of peristalsis

NO - secreted by inhibitory neurons to the descending wave of peristalsis

41
Q

what are the functions of the ascending colon?

A

fermentation - rich in bacteria

absorption - of water and ions

42
Q

what is the advantage of haustra in the ascending colon?

A

increase surface area

43
Q

what are the movements of the ascending colon and what do they do?

A

propulsion and retropulsion - churn and slow transit

segmentation - mixes content and increases exposure to mucosa

44
Q

what controls movement in the colon and rectum?

A

ICCs, local mediators (5-HT) and local environment

45
Q

what occurs in the transverse colon?

A

absorption

relatively rapid transmit

46
Q

what occurs in the descending colon?

A

storage, slow, partly involuntary transit

47
Q

how does the colon decide which way to go?

A

interstitial cells, ENS and extrinsic nervous system

48
Q

explain how the conscious urge to defecate is triggered

A

contents distend rectum
pressure increases passively (increases further by active contraction)
accompanied by relaxation of internal anal sphincter and contraction of external sphincter
contents continue to enter rectum
triggers conscious urge to defecate

49
Q

what normally presents defecation?

A

tone of internal anal sphincter & puborectalis

mechanical effects of acute anorectal angle

50
Q

how is defecation initiated?

A

puborectalis muscle & external anal sphincter relax

intraabdominal pressure increased - facilitated by squatting

51
Q

what is water needed for?

A

Digestion and absorption – hydrolysis is main chemical reaction

Facilitates propulsive movement of intestinal contents

By liquefying intestinal contents, allows digested nutrients to be brought into close contact with absorptive microvilli surface

52
Q

name some conditions of the colon

A

pseudo-obstruction
diarrhoea
slow transit constipation - adult females
chronic constipation - more common in elderly
faecal incontinence

metabolism (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions