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The Body at War. Year 9 2012. Introduction. Health: A state of physical, mental and social well-being. Disease: Said to be present in the body when a part of it doesn’t function normally or properly. VIRUS:. So small they can only be seen with an electron microscope.
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The Body at War Year 9 2012
Introduction • Health: • A state of physical, mental and social well-being. • Disease: • Said to be present in the body when a part of it doesn’t function normally or properly.
VIRUS: • So small they can only be seen with an electron microscope. • They are not considered to be living things as they do not self-reproduce, grow, feed or produce waste. • They move from place to place, but only if they hitch a ride on something: other organisms, wind or water.
VIRUS: • They are not cells. • They are parasitic invaders made of DNA coated in protein. • They attach to a host cell and take it over. • They hijack the cell and reprogram it to make more virus particles. • Eventually there are so many virus particles that the cell breaks open and releases the virus particles which then invade other cells.
VIRUS • They are hard to treat because they are not cells and cannot be stopped by antibiotics. • With most viral infections, you have to wait until your body uses its own defenses to stop and kill the invading virus.
VIRUS examples • Warts http://virus.stanford.edu/papova/2000/papova/virus1.html
VIRUS examples • Rubella http://www.nlm.nih.gov/medlineplus/ency/imagepages/1315.htm
VIRUS examples • Influenza • Common cold • Polio • AIDS
BACTERIA • Identified by their shape. They can be rod-shaped (bacilli), spiral (spirilla) or spherical (cocci). http://en.wikipedia.org/wiki/Bacterial_shape
BACTERIA • All bacteria consist of ONE CELL, but they join together to form pairs, chains or clusters. • Bacteria can multiply very quickly under the right conditions. • Bacteria can remain inactive for days or even years. • Many types of bacteria can be killed using penicillin or other types of antibiotics.
BACTERIA examples • Strep throat http://www.nlm.nih.gov/medlineplus/ency/imagepages/19694.htm
BACTERIA examples • Tetanus • Pneumonia • Food poisoning
FUNGI • Many fungi are parasites that feed on living plants and animals. • This often results in a disease. • Fungi commonly invade hair, nails and skin. • Fungi are opportunistic pathogens – they are not usually associated with infection, but will infect a person if there are ideal conditions or if their immune system is weakened.
FUNGI examples • Tinea (athlete’s foot) http://www.lib.uiowa.edu/hardin/mD/cdc/4803.html
FUNGI examples • Ringworm http://www.lib.uiowa.edu/Hardin/MD/cdc/2938.html
WORMS • A type of parasite • Depend on their host for food
WORMS example • Tapeworms • Can measure up to 10 meters in length. Internal parasites found in the intestines. http://www.ndpteachers.org/perit/biology_image_gallery1.htm
INSECTS example • Lice • External • Thrive on human blood by biting into the skin of their host. http://schoolipm.ifas.ufl.edu/graphics/lice_c.htm
PROTOZOA • Diseases caused by protozoa (protisis) are often seen in tropical/subtropical areas. • Single-celled • Most protozoa are harmless to humans, but some parasitic times can cause serious illness. • Sometimes form cysts around themselves if conditions are unfavorable so they can survive between outbreaks
PROTOZOA • Can contaminate water supplies • Ex. plasmodium is a parasitic protozoan that lives in red blood cells and liver cells and causes malaria. • Amoebic dysentery • African sleeping sickness