Notes 11.7: Immune System Non-Specific defense Pages 957-960

Function Fights pathogens to prevent infections and disease Works with the lymphatic system (collects fluid and returns it to the blood)

structures Bone marrow: produces blood cells Lymphocytes: white blood cells (WBC) Lymph nodes: stores WBC Thymus: matures WBC Spleen: contains WBC that clean out pathogens as blood filters through

Initiating the immune system Antigen: any substance that the immune system responds to Allergens: Cause allergies (pollen, dust mites, mold, etc.)

Initiating the immune system Antigens continued Pathogens: cause disease Viruses: protein shell containing DNA or RNA Bacteria Fungi (spores) Parasites Toxins (snake bites etc)

Nonspecific defense Protects body against any pathogen, regardless of the pathogen’s identity

First lines of defense Mucous membranes Skin Blocks entry Sweat & oil are toxic to many pathogens Mucous membranes Mucous: traps pathogens

First lines of defense Cilia: moves pathogens out of body Stomach acids: destroys pathogens

Second Line of defense: non-specific response Inflammatory Response

Second Line of defense: non-specific response Inflammatory Response 1. Injured cells release a chemical signal called histamine to increase blood flow to area 2. Platelets cause clotting, trapping pathogens 3. Area swells, becomes warm, and macrophages/phagocyte (WBC) move in and engulf bacteria

Second Line of defense: non-specific response Interferons: enzymes that stop virus protein production Fever: hypothalamus sets a higher set point for body temperature, this slows growth of bacteria and increases activity of WBC Should a fever always be treated? Why or why not?

Second Line of defense: non-specific response White blood cells: there are many types, some act in a non-specific way, these WBC are called phagocytes

Second Line of defense: non-specific response Types of phagocytes Neutrophils: Ingest pathogens Macrophage: Engulf pathogens & other cell debris Natural Killer Cells: Burst pathogen infected cells