Brainscape's Knowledge GenomeTM

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


See full index

Gastrointestinal > GI Motility > Flashcards

GI Motility Flashcards

1
Q

Which parts of the GI tract have voluntary skeletal muscle rather than involuntary smooth muscle?

A

Proximal third of the stomach, upper oesophageal sphincter and external anal sphincter

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

Describe what is meant by the slow wave potential of the GI tract

A

These are not action potentials but oscillating depolarisation and repolarisation of the membrane potential of smooth muscle cells. The depolarisation stage brings the smooth muscle closer to the threshold and if an action potential occurs at the top of these slow waves the cyclical contraction of the GI tract will occur

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

What is the intrinsic rate of the slow waves in the stomach?

A

3 waves per minute

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

What is the intrinsic rate of the slow waves in the duodenum?

A

12 waves per minute

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

Which cells are considered the pacemaker cells of the GI tract due to their role in controlling the slow wave mechanism?

A

Interstitial cells of Cajal

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

The intrinsic rate of the contractions of the GI tract doesn’t change but the strength of contraction can be increased or decreased. True or false?

A

True

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

Describe the mechanism of swallowing?

A

The upper oesophageal sphincter open which is mediated by the swallowing reflex. The sphincter closes when the food bolus enters the oesophagus. The swallowing reflex results in a peristaltic wave which pushes the bolus towards the stomach. The vagus nerve mediates opening of the lower oesophageal sphincter and at the same time to topmost part of the stomach relaxes to allow the bolus to flow into the stomach

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

What factors will increase the frequency and force of contractions in the stomach?

A

Parasympathetic innervation
Motillin
Gastrin

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

What factors will decrease the frequency and force of contractions in the stomach?

A

Sympathetic stimulation
Secretin
GIP

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

What is the migrating myoelectric complex?

A

This is a contraction which sweeps the length of the stoma h every 90mins in the interprandial state in order to clear the stomach of any residue. This is mediated by motilin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where is motilin synthesised?

A

M cells in the small bowel

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

What is the affect of erthromycin on motilin?

A

It is a motilin antagonist

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

What is the emptying rate from the stomach for inert liquids?

A

20minutes

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

How long can it take solids to empty from the stomach?

A

3-4 hours

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

Fat and hydrogen ions in the duodenal lumen will inhibit gastric emptying. How is this achieved?

A

Fat stimulates cholecystokinin which increases contraction of the pyloric sphincter
The effect if hydrogen ions is mediated by the enteric nervous system

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

If the small intestine transports solids and liquids at the same rate why are liquids the first to reach the caecum?

A

Because liquids are released earlier from the stomach and into the duodenum than solids

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

Describe the segmentation contractions of the small intestine

A

A section of the small intestine contraction and splits the chyme sending some forward and some backwards. It then relaxes which allows the bolus of chyme to merge back together. This action severs to mix the chyme

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

What is the name of the contractions of the large intestine which move food towards the caecum?

A

Mass movements

19
Q

Explain the control of continence and defecation.

A

As the rectum fills with farces the smooth muscle wall of the rectum and internal anal sphincter relaxes in the recrosphincteric reflex. However, defecation does not occur because the external anal sphincter is still tonically contracted. When this sphincter is voluntarily relaxed, the smooth muscle of the rectum contracts to create pressure that forces faeces through the anal canal

20
Q

Describe what a normal high resolution mannometry trace of a person swallowing would look like

A

Here areas of red shiw high pressure and blue shows low pressure. First, the upper oesophageal sphincter is relaxed (as seen by a break in the solid green line to blue which is the to ically contracted sphincter), a wave kf red and yellow peristaltic wave follows this and the bottom of this wave, contraction of the lower sphincter ceases to allow food to enter the stomach

21
Q

Describe how achalasia leads to difficulties swallowing

A

Here there is no peristaltic contraction due to nerve damage and the lower oesophageal sphincter fails to relax properly. This makes it difficult to eat and patients often have to take large amounts of water to eat a meal and will regurgitate

22
Q

How can achalsia be treated?

A

A balloon can be used to decrease the pressure in the lower oesophageal sphincter
Laprascopic surgery can also be used ti lower oressure in the lower oesophageal sphincter

23
Q

How does scleroderma lead to severe oesophagitis and excessive reflux?

A

Scleroderma is a condition which effects connective tissues and this results in very weak peristalsis and a very weak lower oesophageal sphincter which results in excessive reflux and oesophagitis

24
Q

What is nut racker oesophagus?

A

Hypertensive peristalsis of the oesophagus which has no evident therapies and is associated with pain on swallowing

25
Q

What are the main general causes of delayed gastric emptying?

A 
Idiopathic
Longstanding diabetes
Macro vascular disease
Drug use particularly opiates
Post viral
26
Q

How can delayed gastric emptying treated?

A

Small meals eaten frequently - liquid food
Treat underlying cause
Erythromycin acts as a motilin antagonist
Metoclopramide and cisalpride are 5HT4 agonists
Dopamine antagonists such as dimperidone can be used
Botox can be injected into the pyloric sphincter
Gastric electrical stimulation via an enterra device

27
Q

Acute post operative ileus leads to constipation in the absence if mechanical obstruction. How long does this last?

A

0-24 hours if it occurs in the small intestine
24-48 hours if it occurs in the stomach
48-72 hours if it occurs in the large intestine

28
Q

List the risk factors for acute post operative ileus

A

Open surgery
Prolonged abdominal or pelvic surgery
Delayed enteral nutrition
Peri-operative complications or opiate analgesia

29
Q

Caecal perforations can occur due to acute colonic pseudo obstruction. How is this caused?

A

Large bowel parasympathetic dysfunction commonly after cardiothoracic or spinal surgery

30
Q

What are some of the causes of chronic intestinal pseudoobstruction?

A

Myopathic - Scleroderma or amyloidosis
Neuropathic - parkinsons
Endocrine - diabetes mellitus, severe hypothyroidism
Drugs such as phenothiazines

31
Q

How can colonic transit be investigated?

A

Serial x rays with radioopaque markers

32
Q

How does the drug loperamide work to treat diarrhoea?

A

It stimulates an opiate receptor to decrease tone and activity of the myenteric nerve plexus

33
Q

How does prucalopride work as a laxative?

A

It stimulates the 5HT4 receptor to increase colonic motility

34
Q

How does linaclotide work as a treatment for IBS constipation?

A

Increases the secretion of chloride and bicarbonate ions into the lumen ti increase intestinal fluid and thus speed up colonic transit

35
Q

What are the main general causes of incontinence.?

A

Damage to pudendal nerve
Muscle damage of external anal sphincter
Excessive rectal distension

36
Q

What is hirschrungs disease?

A

A failure of migration of neural crest cells to the distal colon and results in the affected segment if the colon being aganglionic

37
Q

How is hirschrungs disease managed?

A

Surgical resection of the affected colon

38
Q

Approximately how often to haustral contractions occur?

A

Every thirty minutes

39
Q

Explain how the location of hasutra changes with contraction of the large intestine?

A

The relaxed segment which has formed a sac slowly contracts whilst a previously contracted segment simultaneously relaxes to form a new sac - thus the location of the haustra changes

40
Q

What is the purpose of haustral contractions?

A

To mix the colonic contents and expose them to the colonic mucosa to aid absorption

41
Q

How often to mass movements of the large intestine occur?

A

3-4 times a day

42
Q

Which reflex triggers mass movements in 5e large intestine?

A

Gastrocolic reflex

43
Q

Describe the defecation reflex

A

The movement of faces into the rectum distends the rectum causes stretch receptors to initiate the defecation reflex. This reflex causes relaxation of the smooth muscle internal anal sphincter and contraction of the rectum and sigmoid colon walls. Defecation will not occur however until the voluntarily controlled skeletal muscle of the external anal sphincter is relaxed.

44
Q

What happens if, following the initiation of the defecation reflex, the urge to defecate is not followed by relaxation of the external anal sphincter?

A

The distended rectal wall will gradually relax and the urge to defecate will subside. This lasts until the next mass movements pushes more faces into the rectum, distends the rectum further and again initiates the defecation reflex

Gastrointestinal (22 decks)

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