1 of 36 Contents What is Energy Used For? Contracting muscles Transport of active substances...

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Contents

What is Energy Used For?

Contracting muscles

Transport of active substances

Thermoregulation

How energy is made - review

Building large molecules

Summary quiz

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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.

How energy is made – review

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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.

What is energy use for?

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Contents


Contracting muscles


Thermoregulation



Summary quiz

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In order for muscles to have an effect, they must move something in the body.

Often this tends to be a bone.

To allow muscles to contract

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By moving the bone, they create a lever which does some work.

bone

muscle

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

energy

To allow muscles to contract

muscle contracted

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Contents


Contracting muscles


Thermoregulation



Summary quiz

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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?

To build up large molecules from smaller ones

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fats

proteins

minerals

vitamins carbohydrates

water fibre

A balanced diet should contain elements from all 7 groups.

7 groups

The 7 main food groups

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Once we have digested the food from our diet, we release many useful substances.

The body uses the energy from respiration to turn these raw materials into useful substances.

ENERGY

respiration digestion

useful raw materials

Converting food into respiration materials

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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)

Building a new protein molecule 1

albumin is the main protein found in egg-whites

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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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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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Step 4

This digestive process releases the individual amino acids.


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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.

new protein (old)

energy

respiration


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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.

new protein

protein moved to and then used elsewhere in the body

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Contents


Contracting muscles


Thermoregulation



Summary quiz

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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.

Thermoregulation

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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.

Why bother?

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You may remember that enzymes are chemicals that control many of the chemical reactions within our bodies.

Therefore...

37oC

enzymes working well and body is fine.

hotterhottercoldercolder

enzymes work slowly and the body is suffering.

enzymes are heat-damaged and body can become ill.

Temperature and rate of enzyme driven reactions

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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.

REST OF

BODY

The brain senses the bodies temperature by sensing the temperature of blood.

Once it knows what the body temperature is, it can act accordingly.

Testing the temperature

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In order to understand what happens, think about what your body does when it is hot or cold outside.

How do you react?

Reacting to the external temperature

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On a hot day…

Heat stress reaction – feeling the heat

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

outer wall

blood

artery

muscle cells.

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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.

Controlling blood flow to the skin

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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The opposite is also true.

If the muscles relax, the blood vessel could become wider and the blood flow increases.

Increasing the blood flow to increase heat loss

blood flow increasedblood flow constricted

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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 .

blood vessels

We can see that blood can take different directions within the skin.

direction of blood flow

surface of 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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brainbrainBBLLOOOODD

> 37oC

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.

makes the blood flow towards the

surface of the skin

this vessel widens

this vessel constricts

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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.

The heat within the blood escapes to the cool air and the result is that the body’s temperature drops.

blood

skin

airHEAT HEAT HEAT

Remember, respiration produces energy that is needed by the muscles around the blood vessels.

To help maintain a steady body temperature

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Contents


Contracting muscles


Thermoregulation



Summary quiz

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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.

Powering active transport of substances

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high concentration

low concentration

The particles would move from the left side to the right.

Normal diffusion

This particle could be an oxygen molecule that is moving from the alveolus to the blood capillaries within the lungs.

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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.

Energy cost to force transport

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high concentration

low concentration

Active transport gives this process an extra ‘push’.

A helping hand

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Contents


Contracting muscles


Thermoregulation



Summary quiz

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Multiple-choice quiz

1 of 36 Contents What is Energy Used For? Contracting muscles Transport of active substances...

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