The Immune System

Before the 1900’s, no one knew what caused sickness and infection Most people thought evil spirits, swamp gas, or bad luck caused disease

science history Louis Pasteur Theorized that microbes caused disease and killing them could prevent illness. Joseph Lister Theorized that microbes caused infection. One of the first surgeons to disinfect instruments. Robert Koch Began linking certain pathogens to certain illnesses. Example: botulinum causes food poisoning.

Functions To keep out or to fight pathogens that enter your body. To recognize and attack foreign substances in the body.

organs skin white blood cells – macrophage – T cell – B cell

pathogen – something that causes illness. Pathogens can be a virus, bacteria, protein, fungi or protist. virusbacteria protein fungi protist

external defenses Your body’s first line of defense against pathogens is to create a barrier. – skin – breathing passages – mouth – stomach

skin Your skin acts as a barrier to keep pathogens out.

breathing passages Small hairs in your nose and trachea help trap pathogens. They can cause you to sneeze or cough to try and expel the pathogens.

mouth and stomach Saliva and stomach acid can kill some pathogens. Vomiting can also expel pathogens.

internal defenses If a pathogen makes it past the external defenses, the internal defenses begin; – Inflammation – happens with cuts and injuries – Fever – body raises your temperature to try and kill the pathogens. – Immune response – white blood cells are produced.

Immune response white blood cells – cells that travel though the bloodstream and body searching out pathogens. The three types are macrophages, T cells and B cells.

macrophages Destroys pathogens by engulfing and digesting them.

T Cells Helper T cells travel throughout the body looking for pathogens. Killer T cells attack certain pathogens.

B Cells B cells produce chemicals (antibody) that destroy pathogens. Antibodies fight disease.

the immune response A pathogen enters the body – A macrophage finds it, engulfs and destroys it. – A helper T cell finds it activates a killer T cell destroys the pathogen finds a B cell to release antibodies to destroy the pathogen

building immunity The body builds immunity against a disease when it is exposed to pathogens. immunity – the ability to resist or recover from an infectious disease. You are born with some immunities, develop some from being exposed to pathogens and can be vaccinated for others.

building immunity Your body has billions of T and B cells but it doesn’t produce very many for each pathogen. Once you are exposed to a certain pathogen, like chicken pox, your T and B cells produce memory cells. The next time you are exposed to that pathogen, the memory cells trigger the production of a large number of T and B cells for that pathogen.

vaccination vaccine – a substance prepared from killed or weakened pathogens that is introduced into the body to provide immunity. The vaccine triggers the body to make memory cells. Edward Jenner was the first scientist to create a vaccine. It was for small pox.

challenges to the immune system A healthy immune system is very good at keeping us from being sick. However, we are exposed to challenges to out immune systems all the time. – allergies – cancer – immune deficiency – auto-immune disease

allergy - disorder in which the immune system is overly sensitive to a foreign substance. pollen dust mold food medicine animals

cancer - disease in which cells multiply uncontrollably, destroying healthy tissue. Can exist in a tumor or can spread in the blood. Cause: genetics chemicals

immune deficiency – some disease cause the immune system to become weak. The most common for humans is HIV which is the virus that causes AIDS. It causes the immune system to fail.

HIV Virus  The virus that causes aids  The virus gets into T cells and reproduces inside of them  As the T cells die, the body loses it’s ability to fight disease

auto-immune disease – a disease in which the immune system attacks itself. Rheumatoid arthritis is one example.

Preventing Infectious Disease Don’t share items that touch your mouth Wash hands frequently Cover mouth when sneezing or coughing Get 8 hours of sleep Eat a well-balanced diet Regular exercise