HOW THE IMMUNE SYSTEM FUNCTIONS

Your Mission Describe how our Immune system works at a grade school level using super heroes. For example: Antigen= Joker…he’s the bad guy doing harm B-cell = Batman…he “tags” the villain for police T-cell = Commissioner Gordon…he calls for help Macrophage= police…They capture and gobble up the villian

Nonspecific Immunity Your body’s first lines of defense are called INNATE or nonspecific immunity Innate immunity is something you are born with that doesn’t change

Nonspecific Immunity The purpose of the first line of defense is to prevent pathogens from entering the body Skin Tears Stomach acid

Nonspecific Immunity The second line of defense is a cellular and chemical response to infectious diseases that make it past the barriers. This response is nonspecific! – Fever, inflammation, and neutrophils and macrophages (types of white blood cells)

Specific Immunity The third line of defense is an acquired immunity that is designed for specific pathogens. Specific immunity involves macrophages and some other white blood cells called T lymphocytes and B lymphocytes

Overview

Lymphocytes T Lymphocytes: – T killer cells are a type of lymphocyte – T Killer cells secrete a protein called perforin – Perforin inserts itself into the pathogen’s cell membrane, forming a pore (or hole) – T helper cells are another T lymphocyte – T helper cells activate T killer cells and B cells – T killer cells and B cells WILL NOT WORK without T helper cells

Lymphocytes B Lymphocytes: – B cells primary function is to secrete special proteins known as antibodies – Each B cell only makes one particular antibody

Antibodies – work in 3 major ways bind directly to antigens to prevent pathogens from entering or damaging healthy body cells can stimulate other parts of the immune system to destroy the pathogens can mark pathogens so that macrophages can destroy them through phagocytosis (cell eating)

Specific Immunity in Action BACTERIA, VIRUSES, and PARASITES (pathogens) – All have antigens that tell your body that they don’t belong – Macrophages phagocytize (eat) the pathogen. The macrophage transfers the pathogen’s antigens to the surface of the macrophage

The macrophage eats the microbes and transfers the antigen to its surface. It then “presents” the antigen to the helper T cells

Specific Immunity in Action T helper cells “see” the macrophages with antigens from the pathogens T helper then alert the T killer cells and B cells T killer cells destroy pathogens with the perforin proteins B cells make antibodies to destroy pathogens

Specific Immunity in Action Antibodies don’t last forever. However some of the B cells that made them, and some T cells, stay around in the lymph nodes. They store memory of pathogens and their antigens…in case the pathogen ever returns