Defending Against Infection Immune Surveillance - cells monitor the body for infection *These “surveillance cells” ID body cells by their surface protein markers Pathogens - disease carriers - have different protein markers Pathogens are opposed by 3 lines of defense

3 lines of defense 1. Epithelial layers Skin *secretes chemicals *surface is acidic *lysozyme attacks and digests pathogens *host to symbiotic bacteria

3 lines of defense 1.epithelial layers, con’t Mucus membranes of digestive system, nasal passages, lungs, reproductive tract *mucus traps pathogens *cilia sweeps away mucus(+pathogens) *smoking destroys cilia If first line is penetrated.....

3 lines of defense 2. Counterattacks Killer cells: macrophages, neutrophils, natural killer cells Killer proteins: create holes in pathogen’s cell membrane Inflammatory response: a blockade that isolates the damaged area Temperature response: fever - inhibits microbial growth

3 lines of defense 3. Immune System involves 4 kinds of white blood cells killer T cells attack and kill infected cells B cells label invaders for destruction Helper T activate killer T +B cells macrophages consume pathogens and infected cells

Lymphatic and Immune System Consists of cells, vessels, structures, organs, and a fluid called lymph Circulates body fluids and defends against pathogens

Lymphatic and Immune System Interstitial fluid *fluid between cells and blood vessels, draining waste *as this fluid moves into lymphatic vessels its name changes to lymph

Lymphatic and Immune System Lymph *interstitial fluid that has moved into the lymphatic vessels where it meets lymphocytes and travels through nodes *you produce 3L of lymph per day

Lymphatic and Immune System Lymphocytes *white blood/immune cells Vessels *where lymph travels, similar to veins *from capillary size to aorta Ducts very large vessels to drain very metabolically active areas, ex. Brain

Lymphatic and Immune System 600 Nodes *little ‘bulbs’ that lymph passes through *contain many lymphocytes to kill pathogens and ‘eat up’ worn out cells *swollen glands are nodes enlarged with lymphocytes and pathogens during an infection

Lymphatic and Immune System nodes con’t Tonsils are modified nodes of the throat, this position allows quick attack on inhaled or ingested pathogens

Lymphatic and Immune System Additional parts of the immune system: Red marrow produces precurser (baby) blood cells Spleen *largest mass of lymphatic cells in the body *maturation, storage, and fighting of pathogens in blood Thymus site of T-cell maturation

Lymphatic and Immune System Antigens: foreign invaders that cause an immune system response *you have millions of different B cells and million of different T cells to respond to all the millions of antigen types you will encounter *antibodies respond to each antigen as a lock fits a specific key

Lymphatic and Immune System Your immune system must recognize the rest of your body cells as belonging to you and must be able to distinguish between dangerous invaders and non- dangerous invaders *dysfunction leads to....

Lymphatic and Immune System dysfunction Allergies: the immune system over-reacts to non-dangerous invaders *varies in severity from bothersome to deadly Autoimmune diseases: immune system sees your own cells as dangerous invaders and destroys them *Ex. Rheumatoid arthritis, lupus

Attack on the Lymphatic and Immune System HIV virus attacks and destroys the immune system resulting in AIDS AIDS is a collection of diseases that your immune system, if still intact, would have fought off

treasure your immune system