THE IMMUNE SYSTEM The function of the immune system is to fight infection through the production of cells that fight off foreign substances

DISEASE: ● Any change, other than injury, that disrupts the normal functions of the body.

PATHOGEN ● Any disease causing agent ● Diseases caused by pathogens are called infectious disease.

TYPES OF DISEASES: Some are produced by ● outside agents o Bacteria, fungus, virus ● Environmental Factors o Cigarette smoke, toxins ● Inherited o Hemophilia

Agents of Disease: ● VIRUS : VIRUS o tiny particles that invade and replicate within living cells. o Attach to surface of cells and inject their genetic material (DNA) which takes over the cell  Causes the common cold, influenza, chicken pox and warts.

● single-celled organisms o Cause disease by  Breaking down tissue of infected organism for food  Releasing toxins that harm the body  Tuberculosis, meningitis, botulism, anthrax Bacteria

Protists ● any organism that is not a plant, animal or fungus o Cause numerous infectious diseases including malaria, dysentery and African sleeping sickness

Worms ● Flatworms and roundworms o Ingested- infected food o Flatworms from streams Infection with Loa Loa is spread by biting mango flies

Fungi Some can attack the skin causing ringworm and athletes foot

How diseases are spread: ● Inherited ● Vectors – organisms that carry disease causing agents ● Sexually transmitted

The Immune System ● the body’s main defense against pathogens ● “remembers” each type of pathogen that enters the body ● IMMUNITY: the body’s ability to destroy pathogens before they cause disease

Fighting Infectious Diseases: ● Nonspecific defenses: do not discriminate between one threat and another. ● Specific Defenses attack particular disease causing agents

Nonspecific Defense: First line of defense ● THE SKIN – the body’s most important line of defense ● Mucus, saliva, tears- contain enzymes to break down the cell walls of many bacteria ● Stomach acid – destroy pathogens that make it as far as your stomach

Nonspecific Defense: Second line of defense ● INFLAMMATORY RESPONSE a non-specific defense reaction to tissue damage caused by injury or infection o The presence of pathogens triggers the production of millions of white blood cells to fight the infection.

Inflammatory response

Specific Defenses or Immune Response: The reaction of the body to particular pathogens ● ANTIGEN: substance that triggers an immune response.

● proteins that recognize and bind to antigens. ● carried through the bloodstream to attack the pathogen causing the infection. Antibodies:

T cells : ( a type of White Blood Cell ) provide defense against abnormal cells and pathogens ● Killer T cells track down and destroy bacteria, fungi, or foreign tissue that contains an antigen. ● Helper T cells produce memory cells that “remember” the antigen if it enters the body again.

Killer T Cells

VACCINATIONS ● A weakened form of a pathogen to produce immunity ● Stimulates the immune system to create cells that are ready to produce specific types of antibodies

Immune System Disorders: ● ALLERGIES : an overreaction of the immune system to an allergen such as pollen, dust, mold or bee stings. ALLERGIES o Inflammatory response o Releases histamines that increase flow of blood and fluids to the infected area.

Autoimmune Diseases: ● When the immune system makes a mistake and attacks the body’s own cells. o Type 1 diabetes, multiple sclerosis, rheumatoid arthritis

AIDSAIDS: An Immunodeficiency Disease ●AIDS – Acquired Immune Deficiency Syndrome. ●HIV – Human Immunodeficiency Virus o destroys T cells so the body does not have the ability to fight off infections infection that.

Transmission of HIV ● Sex with an infected person ● Shared needles with an infected person ● Contact with body fluids of an infected person ● Infected mother to child

Prevention of HIV ● Safe sex ● Don’t use drugs ● Protect yourself from blood CURE for HIV ● No cure ● The virus mutates. It is drug resistant ● Treatments extend the quality & length of an infected persons life