IB Biology - Investigation of Skin surface temperatureName ______

Date:______

Aim

To investigate changes in skin temperature and to relate these changes to temperature regulation and homeostasis.

It is known that the skin is important in temperature regulation of the body.

Normal blood temperature is 36.5°C and blood flow to the skin is used to regulate body temperature, as are shivering and fur thickness:

Vasoconstriction: reduces blood flow to the skin when the body is cold

Vasodilation:increases blood flow to the skin when the body is warm

Design an investigation of an aspect of Skin surface temperature.

Some ideas –

  • how much does the hair / colothes insulate the skin from heat loss
  • does muscle activity produce waste heat that is measurable on the skin
  • does sweating produce a measurable drop in skin temperature
  • do parts of the skin recover from cooling at equal rates (does blood flow to some parts of the skin than others)

These are general ideas – your experiment needs to have a clearly focussed research question:

Aspect 1:-Crafting a Clearly focussed Research Question
(stating the independent and dependant variables)

Not a Clearly focused question:

I wonder if we can show that shivering really does warm you up? Muscles contract and produce waste heat. Will the skin get hotter, or change colour when muscles shiver?

Step 1 – focus the dependent variable

How will I control the dependent variable? The shivering?
I’ll count the contractions of the biceps muscle.  «Biceps muscle activity»

Step 2 focus the independent variable

Where will I measure the independent variable?

The best place will be the skin next to the biceps muscle

A Clearly focussed Research Question

What is the effect of biceps muscle activity [f1]on the skin surface temperature [f2]of the human[f3] upper arm?

Aspect 2:-Design a method for the effective control of variables

a) Fair testing 1 – identify the other independent variables which could affect the dependent variable (skin surface temperature of human upper arm).

  1. the distance from the muscle to the skin surface___
  1. ______
  1. ______
  1. ______

b) Fair testing 2 – explain how to keep each variable (i to iv) constant during your

experiment

  1. __put the sensor in the same place, and exercise the same muscle
  1. ______
  1. ______
  1. ______

c) Apparatus - list the apparatus you’ll need for the experiment.

Apparatus

  • Skin surface thermometer
  • Tape to hold thermometer in place
  • Stopwatch
  • 1kg mass
  • Metronome

d) Describe your method in steps, so that another student could follow it accurately.

Method

  1. Attach a thermometer strip to the upper forearm with some tape.
  2. Set the metronome ( )to 0 beats per minute
  3. Sit at a bench and lift the 1kg mass every time the metronome beats for 1 minute.
  4. Record the skin surface temperature after 1 minute.
  5. Change arms – to allow the skin to cool between tests.
  6. Repeat steps i to iv twice more.
  7. Repeat the whole experiment with the metronome at 15, 20, 30, 60, and 90 beats per minute. [Note: Work done per lift (J) = 10N * height moved (m)]

Results

Record all your raw data here.

Remember what we learned in the last IA, check the Assessment criteria

Collect data on your own.

This will be an assessment of DCP and CE.

[f1]Includes the independent variable

[f2]Names the dependent variable

[f3]

Includes the name of organism in the experiment