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3A week 2 - lower GI tract > altered GI motility > Flashcards

altered GI motility Flashcards

1
Q

What are the lower GI motility symptoms?

A

Diarrhoea, constipation

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2
Q

what scoring system is used for describing faeces

A

bristol stool chart

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3
Q

What is the definition of diarrhoea?

A

Passage of loose or watery stools, typically at least 3 times a day in a 24hr period.

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4
Q

What are the features of diarrhoea? (2)

A
  1. Reduced consistency
  2. increased frequency
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5
Q

What is dysentery

A

Diarrhoea with visible blood or mucus - commonly have a fever and abdo pain

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6
Q

What time frame is acute diarrhoea?

A

<14 days

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7
Q

What time frame
is persistent diarrhoea

A

14-30 days

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8
Q

what time frame is chronic diarrhoea?

A

> 30 days

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9
Q

What is acute diarrhoea and what causes it (2)?

A

Increased water content of the stool - either due to impaired water absorption and/or active water secretion by
bowel

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10
Q

What causes acute diarrhoea? (3)

A
  1. INFECTIONS: [viral, bacterial, protozoal]
    Rotovirus - kids
    Norovirus - adults
    Schistosomiasis - tropical infection
  2. DRUGS (SE of many drugs)
  3. PSYCHOLOGICAL
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11
Q

What are the two types of chronic diarrhoea?

A

Osmotic and secretory diarrhoea

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12
Q

What is osmotic diarrhoea?

A

Water is drawn into in the bowel due to the presence of solutes within the lumen (natural osmosis), typically due to:
- Ingestion of a poorly absorbed solute
- Malabsorption

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13
Q

How can you reduce osmotic diarrhoea?

A

fasting

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14
Q

What are the causes of osmotic diarrhoea?(7)

A
  1. Carbohydrate malabsorption (e.g., lactose intolerance)
  2. Magnesium-induced (e.g., antacids)
  3. Osmotic laxatives (e.g., lactulose)
  4. Small intestinal mucosal disease (coeliac dx, severe
    Crohn’s, enteritis etc.)
  5. Reduced absorptive area (resection from e.g. Crohn’s)
  6. Bile acid malabsorption!!
  7. Pancreatic exocrine insufficiency (CF, pancreatic cancer - if it blocks pancreatic duct in the head of the pancreas,
    chronic pancreatitis)
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15
Q

How does coeliac’s cause diarrhoea?

A

Stops you absorbing osmolytics - viliae atrophy so reduced absorptive area too

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16
Q

What does the pancreas do?

A

Endocrine and exocrine effects -> to help absorption of food, if it doesn’t work properly, then it will sit in the gut and it will pull water in

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17
Q

Where is bile produced and secreted?

A

Liver produces and secreted by the bile duct

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18
Q

Where does the secreted bile go?

A

Into the duodenum where 95% is then absorbed in the terminal ileum and only 5% is excreted

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19
Q

What does the gallbladder do?

A

Stores bile until fat needs digesting, then the gallbladder is squeezed and bile goes into the duodenum to help the fat be digested

20
Q

What is bile acid diarrhoea?

A

Bile isn’t absorbed (e.g. due to resection of the terminal ileum) and so sits in the gut and draws water in to the gut

21
Q

What is lactulose?

A

Syrup/sugar drink -> non-absorbable sugar that sits in the gut and drags water in (osmotic laxative)

22
Q

What is lactose intolerance?

A

a form of carbohydrate malabsorption - We need lactase in our body to break down milk as babies, and when we get older, the amount of lactase reduces;
More prominent in the East

23
Q

What is secretory diarrhoea

A

Actively increased secretion of fluid and electrolytes

24
Q

What can cause secretory diarrhoea? (6)

A
  1. Bacterial endotoxins (E.coli, cholera, c.diff) -> irritates bowel causing secretions
  2. Stimulant laxatives (senna)
  3. Hormones (hyperthyroidism)
  4. Bile acid malabsorption
  5. Mucosal inflammation (Ulcerative coliits, Crohn’s)
  6. Rectal villous adenoma (an adenoma with villi-like protrusions that means it is less likely for secretions to be absorbed)
25
Q

what is rectal villous adenoma

A

a precancerous secretatory polyp which => the polyps are covered in mucous -> secretes lots of fluid, distal lesion - the body cannot resorb it all)

26
Q

What are the different types of adenoma histologically?

A
  1. Tubulous
  2. villous
  3. tubular-villous
27
Q

How is diarrhoea treated?

A
  1. Treat underlying disorder
  2. Opiates
  3. Anti-secretory drugs (octreotide - somatostatin analogue)
28
Q

How do opiates work to treat diarrhoea?

A

decrease urgency, bowel frequency and stool volume
e.g. loperamide - immodium (+ codeine but more SEs)

29
Q

Why would you not give loperamide (opioid) with
IBD

A

risk of toxic megacolon development

30
Q

erosion vs ulcer (GI)

A

Erosion - superficial/partial break within the epithelium or mucosal surface;
Ulcer - deep break through the full thickness of the epithelium or mucosal surface.

31
Q

why does bowel resection result in osmotic diahhorea

A

reduced absoptive area leads to decreased ability to absorb nutrient => higher osmotic gradient -> more water moves into the bowel lumen

32
Q

why does a Cholecystectomy result in osmotic diahorrea

A

removal of gall bladder means that bile is just being continuously released -> resorptive capacity in the terminal ileum overwhelmed -> more bile in the colon which has an osmotic effect

33
Q

What are the 2 main types of
constipation?

A
  1. Slow colon transit constipation
  2. impaired rectal emptying
    (3. both)
34
Q

How can you differentiate between a defecatory disorder and a slow transit defaecation

A

Shapes study:
Pt ingests radiopaque markers (plastic rings containing radiopaque material) in a meal and abdo XRs are obtained to monitor clearance of the rings from the colon ->
Normal colonic transit time = 20-56 hours, and most adults will clear all the markers in 4-5 days and <20% of the original rings at 5 days = normal

35
Q

What’s constipation?

A

opening bowels less than 3 times a week

36
Q

What are the causes of constipation? (7)

A
  1. Endocrine (hypothyroidism)
  2. Metabolic (hypercalcaemia / hypokalaemia / hypomagnesiumia)
  3. Neurological (PD, MS)
  4. Neuromuscular (MND, MG)
  5. Psychological (brain-gut axis - anxiety)
  6. Physiological (dehydration)
  7. Mechanical (obstruction - malignancy - annular applecore lesion on barium, stricture from chronic IBD)
    [+ drugs - opioids, imodium]
37
Q

How can we generally manage
constipation?

A
  1. Identify any anatomical abnormalities
  2. Identify biochemcial causes
  3. Stop constipating drugs
  4. Exercise
  5. Increase fluid intake
  6. Increase dietary fibre (SEs - bloating, flatulence)
38
Q

constipation mgx + examples (5)

A
  1. Bulk forming laxatives - ispaghula, sterculia (used for mild constipation) - improves bowel frequency
  2. Stimulant laxatives - senna, bisacodyl, sodium picosulphate - increases motility, frequency and improves consistency BUT risk of atonic colon (it just stops
    working)
  3. Stool softeners - liquid paraffin, sodium docusate, arachic oil enema (BUT contains peanut oil) - limited efficacy but
    widely used
  4. Osmotic laxatives - lactulose, magnesium salts (main SE: hypermagnesaemia)
  5. Prucalopride (for IBS-C) - use for constipation is after 6
    months of trying 2 different laxatives. If no benefit, try:
    - Lubiprostone
    - Linaclotide
39
Q

bulk forming laxatives MOA

A

absorb liquid in the intestines and swell to form a soft, bulky stool -> The bowel is then stimulated normally by the presence of the bulky mass

40
Q

stimulant laxatives MOA

A

cause peristalsis by stimulating colonic nerves (senna) or colonic and rectal nerves (bisacodyl, sodium picosulfate) -> parasympathetic stimulation

41
Q

what can be given if a pt is experiencing opioid induced constipation and why

A

Naloxegol - only used once constipation not adequately responded to laxatives ->
It only works in the gut but not elsewhere so it won’t reverse the pain-relief effects elsewhere

42
Q

How does lactulose work and what are 2 side effects

A

Osmotic laxative - Decreases colonic pH by generation of fatty acids and fermentation products, causing water to go by osmosis into the gut
SEs: Bloating, flatulence

43
Q

What can happen with chronic senna ingestion

A

melanosis coli - Deposition of darker pigment -> can see reticulated striations (alligator skin), looks like shadow of water moving in a pool

44
Q

What is the difference between
IBS-C and functional constipation?

A

IBS - Must have pain to have IBS and pain improves after bowel movement usually
Functional - no pain necessarily

45
Q
A

3A week 2 - lower GI tract (8 decks)

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