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The Immune System Part I. Physiology Standards: 10a-e Germ Theory and Non-specific defense. The Germ Theory. The germ theory states that: infectious diseases are caused by microorganisms of different types, commonly called germs
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The Immune System Part I Physiology Standards: 10a-e Germ Theory and Non-specific defense
The Germ Theory • The germ theory states that: • infectious diseases are caused by microorganisms of different types, commonly called germs • Many believed that sickness and poor health was the work of ‘spirits’ or some ‘higher source’ • A disease is any condition that disrupts the normal functioning of the body • A pathogen usually “transmits” the disease to a host Salmonella is a bacterium found on and in all raw chicken!
Agents of Disease • There are many examples of agents for diseases and they fall into 5 major groups: • Viruses – the most common is influenza known as “the flu” • Bacteria – can either break down cells or release toxins into the organism • Protists – a disease that is often transmitted by an animal like malaria from mosquitoes • Worms – worms use humans as hosts while they act like parasites • Fungi – fungus causes infections in warm, moist places like athlete’s foot E. coli is a bacterium found in raw meat
Agents of Disease • Viruses vs. Bacteria • Both cause disease, but they act in different ways • Viruses: • Take over a cell’s DNA and instruct the cell to “make” more viruses • There is no “pill” to cure a virus, only the body can cure itself • Bacteria: • Either destroy tissue or release poisonous toxins within your body causing illness • You can take antibioticsto cure yourself of a bacterial infection Flu virus
Agents of Disease • Protists – single-celled animals • Protists often have a complex lifecycle where they take a couple of forms before infecting humans • Malaria attacks human red blood cells! • Worms – the “tropical” parasite • Flatworms and roundworms are the cause of many diseases and severe discomfort • Ascaris is a dangerous and common roundworm while tapeworms are common flatworms
Disease Transmission • How do you get sick ? • What are three ways you can acquire a disease? • What are the ways to prevent disease? • Name three things you can do daily to prevent catching a sickness.
Your Immune System • The functionof your immune system is to fight infection through the production of cells that inactivate foreign substances or cells • There are two types of defenses: • Non-specific defenses protect against all pathogens equally (the skin is a non-specific defense ) • Specific defenses act like “special soldiers” that are designed to kill a certain type of pathogen (these are the host of white blood cells and other disease fighting cells in your body)
The Immune System • Nonspecific Defense – your “general” defense system against pathogens • The skin is the most important line of defense against nearly all pathogens • The skin is capable of secretions such as oil, mucus, saliva, and tears that create an intolerable environment for many pathogens • Sweat is also a great defense against pathogens!