Main types of drugs are: Stimulants such as caffeine speed up our reaction time and make us more alert. Depressants such as alcohol slow down our reaction time and make us more relaxed. It is dangerous to drive the car after drinking alcohol. Painkillers such as paracetamol or morphine stop pain from travelling to brain by blocking the impulses between neurons (nerve cells). This means we can not feel the pain. Drugs are chemicals that change the way our nervous system works. 1

Tobacco contains lots of substances that can harm our body. This is why smoking can be dangerous. Tobacco contains: Nicotine – which makes you addicted to smoking as it is addictive drug. Depending on the circumstances (personal mood, dose), nicotine can be both stimulant and depressant. Tar – which damages healthy lung cells and causes lung diseases including bronchitis and lung cancer. Carbon monoxide – is toxic gas, which stops red blood cells from carrying oxygen around the body. It hijacks red blood cells. This is particularly dangerous when smoking person is a pregnant woman as a lack of oxygen can have an negative impact on development of a foetus (baby). Why is smoking harmful?

Pathogen is an microorganism that causes disease. It can be: virus (influenza virus, HIV virus,) Flu virus is spread through the air. bacterium ( TB – tuberculosis, cholera, Salmonella) Salmonella is food poisoning bacterium. Cholera is spread in the water. fungus (athlete’s foot) Athlete’s food is spread through Contact with wet surfaces. single celled animal (protoctist) (malaria) Malaria is caused by single celled animal which is spread by mosquitoes.

How is our body protected against pathogens? The human body is covered by skin that prevents pathogens from entering the blood. The pathogen can only enter the blood when the skin is damaged (cuts, wounds) Our stomach produces hydrochloric acid that kills bacteria that enter our body in the food and water.

We can use substances to stop spreading of pathogens Antibiotics – substance that kills or prevents growth of bacteria and some fungi. Kills pathogens inside your body. Antibiotics cannot kill viruses. Antiseptics Kills pathogens on outside of our body, mostly fungi. Antibacterial sprays Kills bacteria on surfaces (kitchen, toilet, bathroom)

Our body needs to keep a lot of things steady to keep us alive and healthy: 1 level of water in our body We loose the water from the body by: sweating breathing out urinating We gain water by drinking. 2 body temperature. We need to keep the steady temperature of 37˚C. Skin helps us with doing it. We sweat more when we are in danger of overheating. 3 level of sugar (glucose) in our blood

Sugar level is controlled by a hormone insulin. When we have high level of sugar in our blood, our pancreas makes insulin and releases it into blood. Insulin removes sugar from blood into liver. People that can not control their blood sugar level suffer from diabetes.

skin structure You need to be able to recognise green underlined parts.

A - Hair muscles in your skin pull hairs on end. B - Erect hairs trap air. Air is good insulator- it does not pass heat easily. C – Blood vessels are buried deeper in your skin. Blood flow in blood vessels decreases. How a hair can help humans and animals keep warm in cold weather. hair hair muscle (erector) blood vessels When your are cold, your skin can help you to keep heat in your body

Reflex arc helps us to respond to stimuli (pain, heat, too much light) around us. It is made of 3 type of nerve cells (neurones). Sensory neuron carries electrical impulse (signal) into spine. Relay neurone makes a response. Motor neurone carries new electrical impulse into muscle that will do the job- response (example, move arm away from danger).