Inside all of the cells of your
body, lots of chemical reactions
are going on all controlled by
enzymes. Your body will not
function properly if you body ...
Is the wrong temperature
Does not have the right amount of water
This is because the enzymes cannot work properly
Has too much carbon
dioxide in the blood.
To maintain a constant internal environment,
inputs and outputs need to be balanced in the
body. This balancing is called homeostasis
The factors shown below are kept at steady
levels by automatic control systems involving
nerves and hormones
The temperature of the human body is usually
kept at around 37 degrees. this is core
temperature (at you fingers and toes it will be
You can measure you
body temperature with
A clinical thermometer in
the ear, mouth or anus
strips on the forehead
Digital recording probes
on a finger, linked to a
Scientists and doctors can also use thermal
imaging. The heat given off by parts of the
body is converted to a visual image. This
shows which areas of the body are warmest
Too hot or too
It is dangerous if your body
temperature goes above or below the
core temperature (37 degrees)
Above 40 degrees you will get
heat stroke and dehydration. If
it is not treated you may die.
Below 35 degrees your boy
develops hypothermia and
if not treated this also leads
How you body gains and looses heat to
keep the core temperature constant.
If you internal organs start to get too hot, the blood flowing through them
carries the heat away. the increased temperature is monitored by the brain.
The brain then brings about mechanisms to control temperature.
Keeping the body's internal environment in a steady state