Temperature Control (Cambridge O Level Biology)

The flow of blood through the skin can be investigated by using a flow-meter.

Fig. 1 shows a flow-meter above a section through the skin.

Fig. 1

State the name of cell P.

[1]

State the types of blood vessel labelled Q, S and T.

[3]

State the name of the tissue at R that provides insulation.

[1]

The blood flow through the skin of some volunteers was measured with a flow-meter when their skin was exposed to different temperatures.

Capsaicin is a compound that gives people the sensation of feeling hot when it is put on the skin. Researchers applied capsaicin to the skin of the volunteers and again measured the blood flow through their skin at different temperatures.

Fig. 2 shows the results.

Fig. 2

Use the information in Fig. 2 to describe the effect of increasing the temperature of the skin surface on blood flow to the skin without capsaicin.

[3]

Explain the mechanism that increases blood flow through the skin.

[3]

State the difference between the average blood flow for the treatments (with and without capsaicin) at 35°C.

Space for working.

__________% [1]

The researchers thought that capsaicin stimulated receptors in the skin.

Explain the process by which capsaicin could reach these receptors.

[3]

Explain the importance of regulating body temperature in humans.

Body temperature is controlled by both hormones and nerves. 

Explain how coordination by hormones differs from coordination by nerves.