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IGCSEBiologyCambridge (CIE)Revision Notes7. Human NutritionHuman Diet & DigestionHydrochloric Acid

Hydrochloric Acid (Cambridge (CIE) IGCSE Biology)

Revision Note

Lára Marie McIvor

Written by: Lára Marie McIvor

Reviewed by: Lucy Kirkham

Hydrochloric Acid

  • The stomach produces several fluids which together are known as gastric juice

  • One of the fluids produced is hydrochloric acid

  • This kills bacteria in food and gives an acid pH for enzymes to work in the stomach

How is a low pH helpful in the stomach?

  • The low pH kills bacteria in food that we have ingested as it denatures the enzymes in their cells, meaning they cannot carry out any cell reactions to maintain life

  • Pepsin, produced in the stomach, is an example of an enzyme which has a very low optimum pH - around pH 2

  • The hydrochloric acid produced in the stomach ensures that conditions in the stomach remain within the optimum range for pepsin to work at its fastest rate

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    Author
    Reviewer
    Lára Marie McIvor

    Author: Lára Marie McIvor

    Expertise: Biology Lead

    Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.

    Lucy Kirkham

    Author: Lucy Kirkham

    Expertise: Head of STEM

    Lucy has been a passionate Maths teacher for over 12 years, teaching maths across the UK and abroad helping to engage, interest and develop confidence in the subject at all levels.Working as a Head of Department and then Director of Maths, Lucy has advised schools and academy trusts in both Scotland and the East Midlands, where her role was to support and coach teachers to improve Maths teaching for all.