Fig. 1 shows an enlarged section of skin from a person who has been outside on a cold, windy day. The hairs are raised and the blood vessels close to the su...
Question 1 Report
Fig. 1 shows an enlarged section of skin from a person who has been outside on a cold, windy day. The hairs are raised and the blood vessels close to the surface are narrow. The body is responding to a fall in internal temperature and reducing energy loss to the air.
(a) Identify the response shown by the narrow blood vessels. [1]
(b) Explain how this response reduces heat loss from the blood. [2]
(c) Use the figure to explain how raised hairs can reduce heat loss. [2]
Answer Details
(a) Vasoconstriction [1] (b) Less blood flows through capillaries near the skin surface [1]; less thermal energy is transferred from blood to the surroundings [1] (c) Hairs trap a layer of air next to the skin [1]; air is an insulator / reduces heat loss by convection [1]
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