2: Physiology and pharmacology of fluid balance and motility Flashcards Preview

Gastrointestinal Week 5 2016/17 > 2: Physiology and pharmacology of fluid balance and motility > Flashcards

Flashcards in 2: Physiology and pharmacology of fluid balance and motility Deck (37)
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1
Q

Diarrhoea is defined as the loss of at least ___mls of fluid per day from the GI tract.

A

500

2
Q

Which ion does water follow into GI cells?

A

Na+

3
Q

Water moves into GI tract cells by ___.

A

osmosis

4
Q

Which transporter couples the influx of glucose and Na+ into enterocytes?

A

SGLT1

5
Q

Apart from glucose, which other molecule is sodium ion influx coupled to?

A

Amino acid influx

6
Q

Which types of GI tract infection can cause diarrhoea?

A

Viral

Bacterial

Parasitic

7
Q

What is the most common bacterium causing diarrhoea in the UK?

A

Campylobacter jejuni

8
Q

Which bacterium most commonly causes Traveller’s diarrhoea?

A

EnteroTOXIC E. coli

9
Q

What non-infectious GI diseases can cause diarrhoea?

A

IBD

IBS

Lactase deficiency

10
Q

Why does hyperthyroidism cause diarrhoea?

A

Increased motility

11
Q

What infection can the use of broad spectrum antibiotics cause?

A

Clostridium difficile

leads to colitis, diarrhoea

12
Q

Increased levels of which molecules lead to increased expression of channels causing increased secretion into the gut?

A

cAMP

13
Q

Toxins produced by infectious agents stimulate the enzyme ___ ___, which increase the levels of ____, which increases gut secretion causing diarrhoea.

A

adenylyl cyclase , cAMP/?cGMP

14
Q

Diarrhoea can lead to ___ due to water loss.

A

dehydration

15
Q

Diarrhoea can lead to ___ ___ due to bicarbonate loss.

A

metabolic acidosis

16
Q

Diarrhoea can lead to ___ due to potassium loss.

A

hypokalaemia

17
Q

Which disease, causing profuse watery diarrhoea, can be fatal if severe?

A

Cholera

18
Q

What is the first line therapy for severe diarrhoea?

A

Fluid replacement (oral/IV)

19
Q

Is coupled glucose/Na absorption affected by diarrhoea?

A

No - this is why fluid replacement therapy works

20
Q

Which channel is used in rehydration therapy?

A

SGLT1

21
Q

Why is salt solution used in rehydration therapy?

A

Takes advantage of coupled glucose/Na transport through SGLT1

And then water follows Na, causing rehydration

22
Q

What do oral rehydration fluids contain?

A

Glucose

Sodium

to take advantage of SGLT1 ⇒ rehydration

23
Q

Why are antibiotics used in a limited role in managing diarrhoea?

A

Most infections are VIRAL (rotavirus, norovirus)

Most bacterial infections are self-limiting so what’s the point in using antibiotics

24
Q

Antibiotics are useful in (self-limiting / severe) diarrhoea.

A

severe

25
Q

Anti-motility agents (loperamide, opiates) are only used in (mild / severe) cases of diarrhoea.

A

mild

you want the mucosa and toxins to be flushed out of the system - anti-motility agents slow this down

26
Q

Opioids cause ___ by decreasing the rate of peristalsis and constricting sphincters.

A

constipation

27
Q

Does the body develop a tolerance to the constipating effects of opioids?

A

No

28
Q

What are some anti-motility agents used in diarrhoea?

A

Loperamide (imodium)

Diphenoxylate

Codeine

29
Q

Why is atropine added to the antimotility agent diphenoxylate?

A

Discourages abuse of diphenoxylate through side effects (nausea, headache, weakness, blurred vision)

30
Q

What is constipation?

A

Production of hard stools requiring straining to pass

and/or

sense of incomplete defecation

31
Q

What is the higher strength version of a laxative?

A

Purgative

32
Q

Many drugs act as laxatives in ___ doses and purgatives in ___ doses.

(low / high)

A

low , high

33
Q

Which drugs should not be used when there is physical obstruction in the bowel?

A

Laxatives

Purgatives

34
Q

Patients with ___ ___ may abuse laxatives to lose weight.

A

eating disorders

35
Q

Why are patients with hernia, angina, eye surgery indicated for laxatives?

A

Straining increases intra-abdominal pressure which will exacerbate the condition

36
Q

Why would laxatives be given to haemorrhoid patients?

A

Rectal bleeding risk

37
Q

The use of which class of drug causes constipation and indicates the use of laxatives?

A

Opioids