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Staying Alive

• When you exercise you breathe deeper and more quickly. Your heartbeat increases.
• Oxygen is needed to release the energy from your food during respiration.
• Breathing in and breathing out are controlled by muscles working your ribs and diaphragm.
• The air you breathe out contains less oxygen and more carbon dioxide than the air you breathe in.
• A candle will not burn for long in breathed-out air because it contains less oxygen.
• Air gets into your lungs through your windpipe and air passages.
• Oxygen passes through air sacs into blood vessels in your lungs.
• Carbon dioxide passes from blood vessels into air sacs in your lungs.
• Mucus traps dust and germs. Tiny hairs carry the mucus up to your nose and throat.
• Tobacco smoke contains harmful chemicals such as nicotine, tar and carbon monoxide.
• Smoking can result in lung cancer, bronchitis and heart disease.
• Your blood carries food and oxygen to the cells and takes away carbon dioxide and waste chemicals.
• Arteries sometimes get 'furred up' and this can slow down blood flow and cause heart disease.
• The right side of your heart pumps blood to your lungs. The left side pumps blood to the rest of your body.
• The 4 main blood types are A, B, AB and O.
• The blood is made up of plasma, red cells, white cells and platelets.
• Red cells contain haemoglobin and carry oxygen.
• White cells protect the body from germs.

Aerobic respiration uses oxygen to get energy from glucose. A glucose molecule can dissolve in blood and is small enough to pass into cells. The energy released in respiration is used to keep the cell alive or is stored for later use in chemical processes. If oxygen is not available as when running or exercising, only some respiration takes place. The sugar cannot break down completely and in muscles this can leads to cramp. This is called anaerobic respiration. It is only temporary and when the muscles receive oxygen once more they can function aerobically.

Oxygen is obtained from inhaled air. The air passes down the trachea (windpipe) and enters the bronchi at the entrance to the lungs. Each bronchus divides into smaller tubes called bronchioles. At the end of the each bronchiole branch are sets of air sacs. These air sacs are called alveoli.

Oxygen from the inhaled air in the alveoli diffuses into the blood. At the same time carbon dioxide from the blood plasma diffuses back in the opposite direction. The alveoli have a very large surface area with thin moist surfaces and an extensive supply of blood vessels. This allows rapid gas exchange. Exhaled air passes back out through the trachea and air passages. Only one third of the air contained in the lungs is exchanged during normal breathing. The lungs only partially empty when you breathe out. Oxygen is transported around the body in the blood by the circulatory system to respiring cells where it enters by diffusion.

Respiration is the process used in all living things for gaining energy. Energy is needed for keeping the vital organs working and generally staying alive. It is also needed for moving muscles. Keeping a constant body temperature is important to. Cell division, reproduction and other important processes in the body all need energy to work.

Breathing in >>> Inspiration
Diaphragm lowers and the ribs raise to increase the volume of the thorax. The pressure decreases so air is drawn into the lungs.

Breathing out >>> Expiration
Diaphragm raises and ribs lower which decreases the volume of the thorax. The pressure increases and air is forced out of the lungs

Blood is carried around the body in blood vessels called arteries and veins. Exchange of substances occurs through tiny tubes called capillaries.

The top chamber is called the atrium, and the bottom chamber is called the ventricle. As you are looking at the heart diagram above, the right atrium is on the left (imagine you are laying on the paper, it helps!). Deoxygenated (blue) blood enters the right atrium from the body and is pumped to the lungs. The oxygenated (red) blood enters the left atrium and is pumped around the body from the left ventricle. Looking at it you can see how much more muscular this part of the heart is, this is because the blood needs to be pumped all around the body from here.

• Investigate the effect of exercise on your breathing rate.
• Use a chest model to show how breathing takes place.
• Measure your chest size during breathing.
• Test your exhaled air for carbon dioxide with lime water.
• Compare the amount of carbon dioxide in inhaled air with that of exhaled air.
• Test your exhaled air for water with cobalt chloride paper.
• Know what artificial respiration is how to apply it.
• Carry out an experiment that shows the difference between fresh air and cigarette smoke.
• Design a leaflet for primary school children to explain why they should not start smoking.
• List the main differences between arteries, veins and capillaries.
• Plan an investigation to see how your pulse and breathing are affected by exercise.
• Use a stethoscope to hear the heart beating.
• List the things that can increase the risk of heart attack and know how to reduce these risks.
• Observe and draw each type of blood cell as seen under the microscope.