1. In This Section We Will Be Studying The Following Topics:
RESPIRATION
In This Section We Will Be Studying The Following Topics:
Why do we need to take in food and oxygen?
Respiration and combustion. How are they linked?
What is aerobic respiration?
How do we exchange gas between the lungs and the blood?
The lungs and how they work.
The different parts of the circulatory system.
Respiration in other living things.

2. WHAT HAPPENS IN RESPIRATION?
A chemical reaction takes place in our cells
Carbon dioxide
Energy
We take in food and oxygen. +
We then have the energy that we need.
We produce carbon dioxide and water.

3. ENERGY Specialist parts of our cells release energy from food.
We need energy so that we can do things.
Energy helps our body to make new cells and to grow.
Move
Grow bigger
Stay warm
Specialist parts of our cells release energy from food.
Muscle cells are packed with these so that lots of energy can be released.

4. RESPIRATION or BREATHING?
Respiration is a chemical reaction that happens in all cells. It is the process of releasing energy from our food.
Breathing is simply the movement of air in and out of the lungs.
They are not the same process.
Think about why we need to resuscitate people by putting air into their lungs.
We also have to push the blood around to the tissues by pushing on the chest.
The oxygen has to get to the body cells so that respiration can take place.

5. TRUE OR FALSE?
Read the following statements and work out which are true and which are false.
Respiration is getting air in and out of our bodies.
Respiration is the process of releasing energy from the food we eat.
Breathing involves getting oxygen into the blood and removing carbon dioxide.
Breathing takes place in the muscle cells.
FALSE
TRUE
TRUE
FALSE

6. + + + COMBUSTION Food Carbon dioxide Oxygen Water Fuel
When Food is used in the cells it also needs oxygen.
The food releases ENERGY, CARBON DIOXIDE and WATER.
When a fuel burns it needs oxygen.
The fuel releases ENERGY, CARBON DIOXIDE and WATER.
The equations for these chemical reactions are exactly the same:
ENERGY
Food
Carbon dioxide + + +
Oxygen
Water
Fuel

7. ‘Respiration’ is a bit like ‘combustion’ Respiration & Combustion
(the burning process).
Look at the table below and say whether each statement applies to respiration, combustion or both.
Fact
Respiration
Combustion
Respiration & Combustion
Gives out heat.
Happens in the cells.
Uses oxygen.
Gives out carbon dioxide.
Needs a high temperature.

8. THE BLOOD Your blood is made up of 4 different parts: Red blood cells.
These carry the oxygen around the body. They have no nucleus and contain a pigment called haemoglobin (this contains iron).
White blood cells.
These destroy bacteria to protect your body. They have a large nucleus.
White blood cell
Plasma.
This is the liquid part of the blood.
Platelets.
These are involved with clotting the blood if you cut yourself. They make a substance called fibrin.

9. BLOOD AND STUFF
Look at the picture below and label each of the four parts of the blood.
Red blood cells.
White blood cells.
Platelets.
Plasma.

10. CIRCULATORY SYSTEM
The blood is the substance that carries oxygen and digested food around your body.
There is a complex system of blood vessels to carry the blood. These are tubes called arteries, veins and capillaries.

11. BLOOD VESSELS
Look at the pictures below and add the name of each type of blood vessel.
Thick muscle wall can withstand blood at high pressure.
Thin wall, carrying blood at low pressure.
Very thin walls, only 1 cell thick.
Artery
Vein
Capillary

12. CIRCULATORY SYSTEM Deoxygenated Oxygenated blood. blood. Lungs. Heart.
Body cells.
Oxygenated
blood.

13. CIRCULATORY SYSTEM Correct order: 1, 5, 2, 4, 3, 6.
Put the following statements into the correct order to explain how the circulatory system works.
Blood picks up oxygen from the lungs.
The heart then pumps the blood to the muscle cells for respiration.
The deoxygenated blood travels from the muscle cells to the heart.
Respiration takes place in the muscles. Oxygen is combined with glucose to release energy. Carbon dioxide is produced as a waste product (so is water).
The oxygenated blood travels to the heart to be passed around the body.
The heart pumps the deoxygenated blood back to the lungs.
Correct order: 1, 5, 2, 4, 3, 6.

14. THE LUNGS The parts of the lungs have different names.
Trachea
(Wind Pipe).
The right and left lung are protected by the rib cage.
The heart is in between these.
Bronchus.
Bronchioles.
Alveolus.

15. THE LUNGS EXHALE INHALE The parts of the lungs have different names.
The tube that takes air from the mouth and nose to the lungs is called the trachea.
The trachea branches into two tubes called the bronchioles.
The tiny blood vessels in the lungs are called the capillaries. These surround the alveoli sacs.
The alveoli are surrounded by capillaries.
EXHALE
INHALE

16. HOW DO WE BREATHE? Large surface area for the exchange of gases.
The lungs need the following things for them to work effectively and exchange gases:
Large surface area for the exchange of gases.
A good blood supply to transport the oxygen around the body.
Moist lining for gases to dissolve.

17. Air is breathed in and oxygen diffuses into the
Once we have breathed oxygen into the lungs, we need to get it into our bloodstream. This happens in the alveoli.
The alveoli are small air sacs that are at the end of the bronchioles.
They are surrounded by capillaries which are carrying the blood.
Carbon dioxide
comes from the
muscle cells and
is breathed out.
Air is breathed in and oxygen diffuses into the
blood capillaries.

18. WHAT DO ORGANISMS DO? Organism Breathe Gas exchange Respire Fish.
Not all organisms breathe in the same way that we do. This is usually because of their habitat and the way their bodies have adapted to it.
Look at the table below and see if you can explain how organisms get their oxygen and if they respire.
Organism
Breathe
Gas exchange
Respire
Fish.
Earthworm.
Plant.
Bacteria.
Humans. X X X X

19. AEROBIC AND ANAEROBIC We become worn out!
When we move or exercise and we do not have enough oxygen we cannot continue.
When we move or exercise and we have enough oxygen we can continue.
We are respiring ANAEROBICALLY.
We are respiring AEROBICALLY.
We get a build up of acid in our muscles because we are not getting rid of the extra carbon dioxide.
We have to slow down or stop to get rid of this acid.
We feel this as CRAMP.
We become worn out!

20. Do other living things respire?
All living things as well as humans respire as they grow and move.
Task.
It is hard to detect this in plants but could you design an experiment to see if a small animal was respiring?
Hint: use limewater to detect any carbon dioxide it might produce.
You would have to use silica gel crystals to see if it was producing any water.

21. LET’S THINK xygn Crbn dxd Rsprtn Brthng Lngs Brnchs Brnchls Lvl Cplly
Can you work out the words?
xygn
Crbn dxd
Rsprtn
Brthng
Lngs
Brnchs
Brnchls
Lvl
Cplly
Rtry Vn
Trch
nrgy

22. LET’S THINK ANSWERS Oxygen. Carbon dioxide. Respiration. Breathing.
Lungs.
Bronchus.
Bronchioles.
Alveoli.
Capillary.
Artery.
Vein.
Trachea.
Energy.

23. Check your learning! Why do we need to take in food and oxygen?
Respiration and combustion. How are they linked?
What is aerobic respiration? What is anaerobic respiration?
How do we exchange gases between the lungs and the blood?
What is made by the cells when the food and oxygen is used?
What job does the heart have in respiration?
Does respiration take place in trees?

24. Check your learning- answers
We use food as the energy source for respiration. We use oxygen with the food in our cells to make the chemical reaction happen.
Respiration and combustion have the same chemical equation.
The food and fuel are both used to release energy.
Aerobic respiration means using oxygen to release energy.
If you do not have enough oxygen you ‘go anaerobic’ and make acid in your cells.
We exchange gases between the lungs and the blood vessels via the alveoli. These are very small sacs with a good network of capillaries.
When food and oxygen are used the body produces water, carbon dioxide and energy is released from the food.
The heart works as a pump to get the blood to the body cells.
Respiration takes place in all living things. Trees and all other plants respire just as all animals do.