Immune System

The Body’s Defense System

Types of Pathogens:Agents that can cause disease…

• Viruses

• Bacteria

• Protists

• Worms

• Fungi

Nonspecific Defenses

• First Line of Defense– Skin, mucus, sweat and tears

• Second Line of Defense– Inflammatory Response

• Production of WBC• Swollen tissue• Fever• Increase of Heart Rate• Interferon release (if viral infection)

Immune Response

• When nonspecific defenses are surpassed, specific defenses start working.

• Antigens: Substance that triggers an immune response

• Lymphocytes– T Cells– B Cells

Humoral Immunity

• Specific defense against pathogens in BODY FLUID

• Antibodies– Attract cells to phagocytize

(“eat”) the antigen– OR cause agglutination

(clumping)– Contains antigen binding

site

Cell-Mediated Immunity

• Defense against body’s own cells that have been infected by a pathogen. (INSIDE OF CELLS)

• T Cells– Develop in bone marrow– Mature in the Thymus– There are many types!

• “Killer” T Cells - KILL• “Helper” T Cells- HELP• “Suppressor” T Cells- WEAKEN• “Memory” T Cells- REMEMBER

Allergies & Transplants

• Allergic Reactions– Mast cells- cause inflammation– Histamines- chemicals released by mast cells– Antihistamine- work against histamines– Asthma- narrowing of air passages

• Organ Transplants- Body sometimes recognizes organ as foreign and can “reject” transplant