Homeostasis
– keeping it balanced
© www.teachitscience.co.uk 2017
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Learning
outcomes:
Be able to name
the internal
conditions which
are controlled in
the body
•
water
content
•
ion content
•
temperature
•
blood sugar
Understand why
it is important
to control these
factors
• Understand
how the body
controls these
factors
© www.teachitscience.co.uk 2017
Keeping it all the same
• There are lots of different chemical reactions
going on in your body.
• If they don’t all work properly you will be ill.
• So your body needs to keep its internal
conditions pretty much the same all the
time.
• This is called ‘homeostasis’.
• Your body needs to control:
• its temperature - a constant body
temperature of 37oC is needed as this is
the temperature at which enzymes work
best.
• the amount of water
• the amount of salts (ions)
• the amount of sugar in your blood.
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Learning
outcomes:
Be able to name
the internal
conditions which
are controlled in
the body
•
water
content
•
ion content
•
temperature
•
blood sugar
Understand why
it is important
to control these
factors
• Understand
how the body
controls these
factors
© www.teachitscience.co.uk 2017
Keeping it all the same
Answer these questions in full sentences:
1. The core temperature of a human should be about
what temperature?
2. Does your skin temperature stay fairly constant,
like your core temperature?
3. What is the effect of exercise on body
temperature?
4. What does your body do to cool down when you
are getting too hot?
5. What does your body do to warm up if you are
getting too cold?
6. Why is it important that body temperature is kept
constant?
Check answers with the following webpage
www.bbc.co.uk/education/guides/z4khvcw/revision/2
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Controlling water
Ways your body gains water
made in cells – 350 cm3
in your food – 800 cm3
drinks – 1450 cm3
© www.teachitscience.co.uk 2017
Ways your body loses water
breathed out – 400 cm3
faeces (poo) – 100 cm3
in urine – 1500 cm3
sweat – 600 cm3
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How does your body control
water?
Learning
outcomes:
Be able to name
the internal
conditions which
are controlled in
the body
•
water
content
•
ion content
•
temperature
•
blood sugar
Understand why
it is important
to control these
factors
• Understand
how the body
controls these
factors
© www.teachitscience.co.uk 2017
•
What are the ways in which your body gains
water?
Made in the body, drinking, in our food
•
What are the ways in which your body loses
water?
In sweat, breathing out, in urine, in faeces
•
If you drink a lot more water than normal, what
do your kidneys do?
You will produce more urine than normal.
•
If you are exercising on a really hot day you will
sweat a lot. How will this affect the amount of
urine you produce?
You will produce less urine than normal.
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Learning
outcomes:
Be able to name
the internal
conditions which
are controlled in
the body
•
water
content
•
ion content
•
temperature
•
blood sugar
Understand why
it is important
to control these
factors
• Understand
how the body
controls these
factors
© www.teachitscience.co.uk 2017
Sugar and salts
• Your body needs to control the amount of
sugar in your blood.
• Sugar is very important as it provides us
with a constant source of energy.
• Your body needs to maintain a constant
level of salts or ions.
• We need to replace salts that are lost in
urine and in sweat.
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Homeostasis – a summary
• Control of the internal conditions of the body is called
homeostasis
__________.
• Internal conditions which are controlled include:
water content of the body - water leaves the body
• the _____
through the lungs when we _______
breathe out, through the
skin
urine
___ when we sweat, and through the kidneys in _____.
ion content of the body - ions are lost through the
• the ___
sweat and through the _______
kidneys in urine.
skin when we _____
• temperature - to maintain the temperature at which
enzymes
_______ work best.
• blood sugar levels - to provide the cells with a constant
energy
supply of ______.
Words to use:
homeostasis, breathe, enzymes, ion, kidneys, urine, sweat, water, skin
© www.teachitscience.co.uk 2017
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