ENDOCRINE SYSTEM AND HOMEOSTASIS

Flight or Fright Hormone

Tell a friend that you wish to find out his/her pulse and breathing rate. Count the number of pulse beats and breaths in one minute.

Now give your friend a fright (e.g. throw a plastic spider on him/her). (Do not do this to a person with a heart problem!) Immediately count the number of pulse beats and breaths in one minute.

When a person has a fright, a hormone called adrenaline is released into the bloodstream. It speeds up the heart and breathing rate to transport more oxygen to the muscles. It also allows more sugar to enter muscle cells. This readies the person to 'fight' if their opponent is small, or 'flight' or run away if the opponent is too big.

How Important is Warmth to Ants

Safety rules:

Parent supervision

Do not do this if you are allergic to insect bites

Materials you need are:

a small clear jar with an airtight lid

sugar

a container of warm water

a container of cold water with icecubes

In the garden, put a few grains of sugar in the jar and wait to catch about 6 ants. Seal the lid. Observe the activity of the ants for 15 minutes (e.g. Are they standing still? Are they running around? Are they eating some sugar?).

Now hold the jar partly immersed in the warm water and observe their activity for 15 minutes.

Then place the bottom of the jar in the container of very cold water, but hold you warm hands wrapped around the top of the jar. Observe for a further 15 minutes. What do the ants do?

You've finished the experiment so you can let the ants go in the garden.

If animals are too cold, they will move to a warm place. This is an example of homeostasis or ' body balance' where the body tries to maintain an optimum body temperature for functioning.