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Exam questions · Biology · Homeostasis

Thermoregulation and the Skin

  • 6 exam questions
  • 19 marks
  • 9 quick checks
  1. 1 State [1 mark]

    State the part of the brain that coordinates the response to a change in body temperature.

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    Model answer

    The hypothalamus.

    Mark scheme

    • Hypothalamus — 1 mark
  2. 2 Describe [2 marks]

    Describe the role of the epidermis.

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    Model answer

    The epidermis is the outer layer of the skin. It forms a barrier that stops pathogens from getting into the body and water from leaving it.

    Mark scheme

    • Outer layer, a barrier — 1 mark
    • Stops pathogens or water loss — 1 mark
  3. 3 Explain [3 marks]

    Explain how sweating helps to cool the body.

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    Model answer

    The sweat glands in the dermis release sweat onto the surface of the skin. The sweat evaporates, and evaporation needs heat energy, which is taken from the skin. So the skin and the body are cooled.

    Mark scheme

    • Sweat released onto the skin — 1 mark
    • Sweat evaporates — 1 mark
    • Takes heat from the skin — 1 mark
  4. 4 Explain [3 marks]

    Explain why shivering helps to warm the body.

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    Model answer

    When a person shivers, the muscles contract and relax very quickly. This needs energy from respiration, and respiration in the muscle cells releases heat energy, which warms the body.

    Mark scheme

    • Muscles contract rapidly — 1 mark
    • Respiration in the muscle cells — 1 mark
    • Releases heat energy — 1 mark
  5. 5 Describe [4 marks]

    Describe the role of the hypothalamus in the control of body temperature.

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    Model answer

    The hypothalamus has receptors that monitor the temperature of the blood, and it receives impulses from temperature receptors in the skin. It acts as the coordination centre, and compares the temperature with the normal level. It sends impulses to the effectors, such as the sweat glands and the muscles, which respond, so that the temperature returns to about 37 °C.

    Mark scheme

    • Monitors the temperature of the blood — 1 mark
    • Receives impulses from receptors in the skin — 1 mark
    • Coordination centre, decides on the response — 1 mark
    • Sends impulses to effectors — 1 mark
  6. 6 Evaluate [6 marks]

    Explain how the skin and the hypothalamus work together to keep the body temperature at about 37 °C when a person moves from a cold room to a hot room.

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    Model answer

    The temperature receptors in the skin detect the rise in the temperature of the surroundings, and the hypothalamus detects that the blood is warmer. The hypothalamus is the coordination centre, and it sends impulses to the effectors. The sweat glands in the dermis release more sweat, which evaporates from the skin and takes heat from it, so the body is cooled. The muscles stop shivering, and the hairs lie flat, so less air is trapped and heat can be lost. As the body temperature falls back towards 37 °C, the hypothalamus reduces its signals. The responses reverse the change in temperature, which is negative feedback.

    Mark scheme

    • Receptors in the skin detect the change — 1 mark
    • Hypothalamus is the coordination centre — 1 mark
    • Impulses sent to the effectors — 1 mark
    • More sweat, which evaporates — 1 mark
    • Cooling by taking heat from the skin — 1 mark
    • Negative feedback restores the temperature — 1 mark

Quick check

  1. 1

    Which part of the brain is the thermostat of the body?

    1. AThe cerebellum
    2. BThe medulla
    3. CThe cortex
    4. DThe hypothalamus
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    D: The hypothalamus

    The hypothalamus monitors body temperature.

  2. 2

    Which layer of the skin contains the sweat glands?

    1. AThe epidermis
    2. BThe dermis
    3. CThe fat layer
    4. DThe hair
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    B: The dermis

    The dermis.

  3. 3

    How does sweat cool the body?

    1. ABy evaporating and taking heat from the skin
    2. BBy absorbing heat from the blood
    3. CBy making hairs stand up
    4. DBy warming the air
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    A: By evaporating and taking heat from the skin

    It evaporates, and takes heat energy from the skin.

  4. 4

    Where does the heat in shivering come from?

    1. ADigestion
    2. BPhotosynthesis
    3. CRespiration in the muscle cells
    4. DEvaporation of sweat
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    C: Respiration in the muscle cells

    Respiration in muscle cells.

  5. 5

    What do the hairs do when the body is cold?

    1. AThey lie flat
    2. BThey stand up and trap air
    3. CThey fall out
    4. DThey produce sweat
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    B: They stand up and trap air

    They stand up, and trap a layer of air.

  6. 6

    What is the role of the epidermis?

    1. AIt stores fat
    2. BIt contains sweat glands
    3. CIt detects temperature
    4. DIt is a protective barrier
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    D: It is a protective barrier

    It is a protective barrier.

  7. 7

    Which of these is an effector in thermoregulation?

    1. AA sweat gland
    2. BA temperature receptor
    3. CThe hypothalamus
    4. DA neurone
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    A: A sweat gland

    A sweat gland carries out the response.

  8. 8

    What happens to the sweat glands when the body is cold?

    1. AThey release more sweat
    2. BThey burst
    3. CThey release little or no sweat
    4. DThey make shivers
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    C: They release little or no sweat

    They release little or no sweat.

  9. 9

    What type of control is thermoregulation?

    1. APositive feedback
    2. BNegative feedback
    3. CNo feedback
    4. DRandom control
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    B: Negative feedback

    Negative feedback.