The Immune System

The Job of the Immune System The immune system protects our bodies from a variety of pathogens (organisms that cause diseases).

Types of Pathogens *Virus-ultramicroscopic infectious agent that replicates itself only within cells of living hosts.

*Carcinogens- any substance that produces cancer.

*Pollution- undesirable state of the natural environment being contaminated with harmful substances as a consequence of human activities .

*Germs- microbe: a minute life form (especially a disease-causing bacterium)

*Toxins- is a poisonous substance produced by living cells or organisms.

*Fungi- including yeast, molds, smuts, mushrooms, and toadstools; distinct from the green plants.

*Bacteria- single-celled or noncellular spherical or spiral or rod-shaped organisms lacking chlorophyll.

*Parasites- an animal or plant that lives in or on a host (another animal or plant); it obtains nourishment from the host without benefiting or killing the host.

How Diseases are Spread *Person to person -Direct physical contact (kissing, hugging, shaking hands). -Indirect contact such as sneezing and coughing. *Contaminated Objects -Water and food -Using towels and silverware -Contaminated nail *Animal Bites -Animals biting a person can transfer the pathogen. *The environment -Naturally occurring in soil and water.

How does the body defend itself? Barriers -Breathing passages Skin Mouth and stomach