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| Pregunta | Respuesta |
| B1c - Staying Healthy | . |
| Key words: | Pathogens - are organisms that cause disease. Parasites - are organisms that live on or in a host organism. Protozoan - a type of single-celled organism. Vectors - Organisms that spread disease, rather than causing it themselves. |
| Malaria | Malaria is a disease caused by a protozoan, a type of single-celled organism. The protozoan is called Plasmodium, it feeds on human red blood cells. The malaria parasite is spread from person to person by mosquitoes. These insects feed on blood and the malaria parasite is passed on when the mosquito takes a meal. Organisms that spread disease, rather than causing it themselves, are called vectors. The mosquito is the vector for malaria. |
| Continue... | It is important to understand the life cycle of a pathogen and the way in which vectors spread the pathogen. This knowledge gives scientists ideas about how the spread of a disease might be controlled. If the life cycle of a pathogen can be broken, eventually all the individuals of that pathogen will die out, leaving a disease-free population. |
| Cancer | A cancer happens when cells begin to divide out of control. They form tumours that can sometimes be felt as an unusual lump in the body. Tumours can be benign or malignant, - benign tumours grow slowly and are usually harmless – warts are benign tumours - malignant tumours often grow more quickly and may spread throughout the body. |
| Body Defences | - The skin -Blood Clotting, The blood contains tiny structures called platelets, and a protein called fibrin. A scab is basically platelets stuck in a fibrin mesh. - Mucus - Nasal hairs keep out dust and larger microorganisms. Sticky mucus traps dust and microbes, which are then carried away by cilia. These are tiny hairs on the cells that line the respiratory system. Stomach acid - Hydrochloric acid in the stomach kills harmful microorganisms that might be in the food or drink that we swallow. |
| Immunity | White blood cells can: - engulf pathogens and destroy them - produce antibodies to destroy pathogens - produce antitoxins that neutralise the toxins released by pathogens. |
| Continue... | Pathogens contain certain chemicals that are foreign to the body, called antigens. Some white blood cells can make antibodies. These are proteins that have a chemical 'fit' to a certain antigen. When a white blood cell with the appropriate antibody meets the antigen, it reproduces quickly and makes many copies of the antibody to neutralise the pathogen. |
| Active/Passive immunity | Active immunity: you make your own antibodies. Passive immunity: you receive antibodies, rather than make them yourself. |
| Immunisation (higher) | Vaccination involves putting a small amount of an inactive form of a pathogen, or dead pathogen, into the body. Vaccines can contain: - live pathogens treated to make them harmless - harmless fragments of the pathogen - toxins produced by pathogens - dead pathogens. |
| Drug Testing | Antibiotics destroy a pathogen. Excessive use of antibiotics has resulted in resistant forms of bacteria being more common than non-resistant forms. |
| Continue... | A placebo is a harmless pill. Placebo are used as a comparison in drug testing so the effect of a new drug can be assessed. In a double blind trial, the patient nor the doctor know which group has the placebo and which group have the real drug. |
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