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The Principles and Importance of Homeostasis

Homeostatic principles, normal ranges and feedback

  • 3 things to know
  • Components 01, 02 and 03

Overview

Recall questions on homeostasis, receptors, coordination centres and effectors, negative feedback, the normal ranges of core temperature, blood pH, fasting blood glucose and blood pressure, and positive feedback through oxytocin in labour.

What you need to know

Answer each one before you reveal it.

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Key term

Why are normal values for physiological factors quoted as ranges rather than as single fixed figures?

Key term

Define homeostasis.

Key term

Name the three functional components of a homeostatic control system, in the order that information passes through them.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Define homeostasis.

    Model answer

    Homeostasis is the maintenance of a stable internal environment within narrow limits, despite changes in the external environment.

  2. 2

    Name the three functional components of a homeostatic control system, in the order that information passes through them.

    Model answer

    A receptor that detects the change, a coordination centre that processes the information, and an effector that brings about the corrective response.

  3. 3

    How does negative feedback return a factor to its normal level?

    Model answer

    A receptor detects the deviation from the set point and the effector is stimulated to produce a change in the opposite direction, so the factor is brought back towards normal and the original stimulus is removed.

  4. 4

    Why does holding temperature and pH steady matter so much for metabolism?

    Model answer

    Enzymes work fastest at an optimum temperature and pH, so keeping these constant maintains high reaction rates and prevents the enzymes from being denatured.

  5. 5

    State the normal core body temperature of a healthy adult.

    Model answer

    Core body temperature is normally about 37 °C.

  6. 6

    What is the normal pH range of human arterial blood?

    Model answer

    Blood pH is normally held between about 7.35 and 7.45.

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Core body temperature is normally about 37 °C.
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