There are many living things that are so small they can only be seen through a microscope. They are known as microbes or micro-organisms.
There are three types of microbes: Fungi, Bacteria&viruses.
Examples of Fungi are mushrooms&toadstools. Mushrooms and toadstools are made with lots of cells. So they are not microbes.
Yeast is a single celled fungi so it is a microbe. Fungi is the biggest type of microbe. If it was just one it would be called Fungus.
Viruses are the smallest types of microbe. Viruses can only reproduce inside a cell.
Bacteria is usually smaller than fungi. One of them is called bacterium. Bacteria have different shapes. Some of them have tails which are called flagella that let them swim.
Some microbes are harmful to us and some are not.
Yeast is useful to bakers and brewers. Yeast can change sugar into carbon dioxide and alcohol. Bakers need carbon dioxide gas to make the bread rise and brewers need to add the alcohol to their drinks.
Bacteria is also useful. Certain bacteria helps milk turn into yogurt and cheese out if it.
Some are diseases caused by fungi such as thrush and athlete's foot.
Microbes cause disease when they are able to reproduce. They produce harmful toxins and damage tissues and organs.
Antibiotics stop bacteria reproducing and kills all bacteria. They only work against bacteria.
Microbes have chemicals called antigens. Different microbes have different antigens.
We all have an immune system that kills microbes that get past our natural barriers.
White blood cells engulf microbes and kill them and they make antibodies that stick to microbes.
Natural barriers: Acid in the stomach kills many microbes. Mucus in the lungs traps microbes and cilia sweep it out of the mungs. The skins stops microbes from getting into the body. Scabs form when you get a cut.
Diseases caused by bacteria: Tuberculosis, Salmonella&whopping cough.
Diseases caused by viruses: Chicken pox, common cold, flu, measles&mumps.
Microbes can spread in a varaity of ways.
Animals:Some animals carry harmful microbes. The microbes can get into people when they are bitten or scratched by an animal. Malaria is spead by mosquitos.
Food:Food can have harmful bacteria on it. The microbes get into the body when the food is eaten. Causing food poisining. If you cook food most of the microbes are killed but microbes can survive undercookin. Carlessness can increase the risk of harmful microbes.
Water: water can carry harmful microbes. Microbes get into the body when water is swallowed. Cholera is spread like this. By boiling water or adding chlorine to the water it can reduce the spread of microbes.
Touch;Microbes can spread when people touch each other or when something is handled by someone. Athlete's foot is spread like this. Antispectics can kill microbes on the skin&disinfectants can kill microbes on surfaces.
Air:Droplets containing microbes fly in the air. Then when people breath in they breath in the microbes. Chicken pox, colds&flu spread like this.