The Immune System

Review What organisms that we’ve learned about can cause disease? Bacteria, protists, fungi, animals, viruses

Pathogens Anything that causes a disease. Can be spread through soil, contaminated water, infected animals (including people)

Reservoirs of Pathogens Anything that harbors infectious microorganisms is called a reservoir. The main reservoir for pathogens affecting humans is the human body itself.

4 Ways to Spread Disease Direct Contact By an object Through the air By a vector Intermediate organism

What are some of the damages caused by viruses?

Damage Caused by Bacteria Most caused by toxins Toxins can inhibit protein synthesis, destroy blood cells and blood vessels, produce fever, disrupt the nervous system.

Patterns of Disease Endemic Disease: Constantly present Epidemic: Emerges and infects many individuals in a population.

Fighting Disease Innate Immunity: Body’s first line of defense Acquired Immunity: Comes about over time through experience with a specific pathogen.

Innate Immunity Skin and body secretions Inflammation of body tissues Phagocytosis of Pathogens Protective Proteins

Innate Immunity: White Blood Cells Phagocytes: Engulf and destroy pathogens Macrophages: Largest, found in body tissue In some cases, a buildup of white blood cells, body fluid, and dead pathogens occur. This is called pus.

Protective Proteins Interferons: Protect specific host cells from viruses

Acquired Immunity: Lymphatic System Lymph is the tissue fluid that circulates through your body. Has small masses throughout the system containing white blood cells called lymph nodes. Contain lymphocytes, a type of white blood cell

Active Immunity T Cells 2 Types Helper T, activates B cells to produce antibodies Killer T, attacks an infected cell directly B Cells Can be activated by T cells to produce antibodies. Non-activated cells become memory B cells. Memory B cells attack directly if the same pathogen invades again.

Passive vs Active Immunity Passive Antibodies are transferred from mother to child. Can be done artificially by injecting antibodies from an animal or human that is immune to a disease. Active Obtained when a person is exposed to a pathogen. Vaccination is a common method but it can occur naturally.