Transcript KS4 What is Energy Used For

Contents
What is Energy Used For?
How energy is made - review
Contracting muscles
Building large molecules
Thermoregulation
Transport of active substances
Summary quiz
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How energy is made – review
Remember, cellular
respiration occurs all
over the body.
Energy
Therefore this energy is used for the many processes
that sustain life.
Amongst all these, there are a few important uses that we
can examine.
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What is energy use for?
1
To allow muscles to contract
2
To build up large molecules from smaller ones
3
To help maintain a steady body temperature
4
To power the active transport of substances within
the body
We will consider each one in turn.
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Contents
What is Energy Used For?
How energy is made - review
Contracting muscles
Building large molecules
Thermoregulation
Transport of active substances
Summary quiz
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To allow muscles to contract
In order for muscles to have an effect, they must move
something in the body.
Often this tends to be a bone.
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To allow muscles to contract
By moving the bone, they create a lever which does
some work.
muscle
bone
Using energy generated within the muscle, it contracts
and alters the position of the bones. In doing so, work
can be done e.g. something can be lifted.
muscle
relaxed
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energy
muscle
contracted
Contents
What is Energy Used For?
How energy is made - review
Contracting muscles
Building large molecules
Thermoregulation
Transport of active substances
Summary quiz
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To build up large molecules from smaller ones
In order for the human body to maintain the metabolic
processes within our cells, it must obtain nutrients from
the 7 food groups.
Do you remember what these are?
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The 7 main food groups
7 groups
fats
proteins
minerals
vitamins
water
fibre
carbohydrates
A balanced diet should contain elements from all 7 groups.
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Converting food into respiration materials
Once we have digested the food from our diet, we
release many useful substances.
digestion
respiration
ENERGY
useful raw
materials
The body uses the energy from respiration to turn
these raw materials into useful substances.
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Building a new protein molecule 1
A simple example of this use of energy can be seen
when the body builds new proteins from amino acids.
Step 1
Proteins are eaten as part of our food (e.g. protein in
eggs)
albumin is the main protein
found in egg-whites
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Building a new protein molecule 2
Step 2
These proteins are made of amino acid chains.
The order of the amino acids is specific to the protein.
amino acids
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Building a new protein molecule 3
Step 3
This protein may not be the one that the body requires.
Therefore, the digestive system uses protease enzymes
to break up the amino acid chain.
enzyme action
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Building a new protein molecule 4
Step 4
This digestive process releases the individual amino acids.
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Building a new protein molecule 5
Step 5
With the raw materials now free, the body can use energy
from respiration to assemble them into new proteins.
A new protein will have a different order of amino acids.
energy
respiration
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new protein
(old)
Building a new protein molecule 6
Step 6
This new protein, and others like it, will now be used in
different ways by the body.
The energy from respiration has made this possible.
protein moved to and
then used elsewhere
in the body
new protein
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Contents
What is Energy Used For?
How energy is made - review
Contracting muscles
Building large molecules
Thermoregulation
Transport of active substances
Summary quiz
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Thermoregulation
The conditions outside our body are constantly changing.
One minute they can be hot, the next cold.
Despite this, our bodies must be kept at a constant
temperature.
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Why bother?
This constant temperature is 37oC.
The reason why our bodies must remain at 37oC is
because this is the temperature at which our
enzymes work most effectively.
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Temperature and rate of enzyme driven reactions
You may remember that enzymes are chemicals that
control many of the chemical reactions within our bodies.
Therefore...
colder
enzymes work
slowly and the
body is suffering.
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37oC
hotter
enzymes
working well and
body is fine.
enzymes are heatdamaged and body
can become ill.
Testing the temperature
The temperature of the body is controlled by a region
of the brain.
As blood flows
around the body, it
also visits this
‘thermo-regulatory’
centre in the brain.
The brain senses the
bodies temperature
by sensing the
temperature of blood.
REST
OF
BODY
Once it knows what the body temperature is, it can act
accordingly.
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Reacting to the external temperature
In order to understand what happens, think about what
your body does when it is hot or cold outside.
How do you react?
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Heat stress reaction – feeling the heat
On a hot day…
You sweat.
Blood is pumped to the surface of
your skin.
If we consider the second of these effects, we can see
where the energy from respiration is used.
Remember that blood flows through vessels which
are lined with muscle cells.
blood
outer wall
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artery
Controlling blood flow to the skin
These muscle cells contract and relax using energy
from respiration.
The contraction and relaxation of these muscles can
affect the blood flow through the vessel.
For example, if the muscle runs in a circular direction
around the vessel, when it contracts, it could constrict
the blood flow.
blood flow constricted
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Increasing the blood flow to increase heat loss
The opposite is also true.
If the muscles relax, the blood vessel could become
wider and the blood flow increases.
blood flow constricted
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blood flow increased
Altering blood flow direction
Let’s consider more closely the blood vessels within the skin,
to see how blood vessel muscles affect the blood flow .
surface of the skin
blood
vessels
direction of blood flow
We can see that blood can take different directions
within the skin.
When the brain senses that the body is too hot, it takes
steps to redirect the blood flow towards the surface of
the skin.
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Sequence of events
The brain can cause the contraction and relaxation of
muscles within the walls of these blood vessels.
Energy from respiration is used to power the
contraction of these muscle cells.
brain
B
L
O
O
D
> 37oC
makes the blood
flow towards the
surface of the skin
this vessel
widens
this vessel constricts
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To help maintain a steady body temperature
When the blood flows to the surface, it comes into close
contact with the air surrounding the body.
This air is much cooler than the temperature of the blood.
HEAT
HEAT
HEAT
air
skin
blood
The heat within the blood escapes to the cool air and the
result is that the body’s temperature drops.
Remember, respiration produces energy that is needed by
the muscles around the blood vessels.
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Contents
What is Energy Used For?
How energy is made - review
Contracting muscles
Building large molecules
Thermoregulation
Transport of active substances
Summary quiz
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Powering active transport of substances
This is our final use of the energy generated during
respiration.
In order to understand how active transport works, we
must firstly consider the concept of diffusion.
Diffusion is the movement of a substance from an area of
high concentration to an area of low concentration.
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Normal diffusion
The particles would
move from the left side
to the right.
high
concentration
low
concentration
This particle
could be an oxygen molecule that is
moving from the alveolus to the blood capillaries within
the lungs.
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Energy cost to force transport
But what if the supply of oxygen (or another molecule)
was not fast enough?
This is when active transport comes into play.
Active transport requires energy.
This energy comes from respiration.
Active transport uses energy to speed
up the process of diffusion.
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A helping hand
Active transport gives this
process an extra ‘push’.
high
concentration
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low
concentration
Contents
What is Energy Used For?
How energy is made - review
Contracting muscles
Building large molecules
Thermoregulation
Transport of active substances
Summary quiz
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Multiple-choice quiz
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