3.2.3 Cholera Flashcards Preview

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Flashcards in 3.2.3 Cholera Deck (17)
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What is the cause of cholera?

Bacterium - Vibrio cholerae


Describe the physical appearance of Vibrio cholerae

  • Curved, rod-shaped bacterium
  • Has a flagellum 


Name 4 ways cholera is transmitted

  1. Drinking water that hasn't been purified
  2. Untreated sewage leaching into water courses
  3. Contaminated food
  4. Eating other organisms (e.g. shell fish) that have fed on untreated sewage


Name 3 precautions to prevent the transmission of cholera

  • Effective water / sewage treatment
  • Improved hygiene
  • Vaccination
  • Prevent water contamination
  • Quarantining of affected area


Name two symptoms of cholera

  • Diarrhoea
  • Dehydration


Describe how cholera bacterium causes disease (6 steps)

  1. In small intestine: bacteria uses its flagella to go through mucus lining of intestine
  2. Produce toxin protein which binds to specific receptors on cell membrane
  3. Toxic protein causes ion channels to open & chloride ions move into lumen 
  4. Loss of ions from epithelial cells = concentration gradient → ions diffuse into epithelial cells from surrounding tissues & blood
  5. ↓Ψw in lumen = water move by osmosis from blood/tissues into lumen down Ψw gradient
  6. Less water reabsorbed = symptoms of cholera


Why does the cholera toxin (exotoxin) only affects the small intestine?

  • Exotoxin specific to epithelial cells in small intestine
  • Only binds to these specific receptors on membrane
  • ∵ they're complementary shape of exotoxin


Name 3 causes of diarrhoea

  • Damage to epithelial cells lining intestine
  • Loss of microvilli due to toxins
  • Excessive secretion of water due to toxins


What is just drinking water ineffective to cure cholera?

  • Water is not being absorbed from intestine
  • Doesn't replace electrolytes (ions) that are being lost from epithelial cells of intestine


Name 5 things a rehydration solution contains

  • Water
  • Sodium
  • Potassium 
  • Glucose
  • Other electrolytes 


Why does a rehydration solution contain sodium?

To replace sodium ions lost from epithelium of intestine


Why does a rehydration solution contain water?

To rehydrate tissues


Why does a rehydration solution contain potassium?

Replace lost potassium ions and stimulate appetite


Why does a rehydration solution contain glucose?

To stimulate uptake of sodium ions i.e. make use of the sodium-glucose carrier proteins

& provide energy 


Why does a rehydration solution contain electrolytes?

Help prevent electrolyte imbalance


How should the rehydration solution be taken?

Regularly and in large amounts, throughout illness


Explain how an oral rehydration solution replaces water lost by diarrhoea (4)

  • Increase uptake of sodium ions/glucose
  • By (sodium-glucose) co-transport carrier proteins
  • Lowers water potential in cell/tissue
  • Water moves out of intestine/into cells by osmosis

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