Immunity Your body’s defense against infection!

Immune System A group of organs and tissues that protect you from foreign invaders Skin Thymus gland Bone marrow Spleen Lymph nodes White blood cells Antibodies

Passive Immunity (innate immunity) Structures that are there already (because of your genes) that protect you from foreign invaders

SKIN Physical barrier against invasion Epidermis- layer of dead skin cells constantly replaced by cells underneath Oils and sweat acidify surface, contain enzymes that digest bacteria

Stomach acid Hydrochloric acid and enzymes destroy bacteria that you swallow Hydrochloric acid of stomach has a pH of 1- 2= kills most bacteria that you swallow Stomach also has enzymes that destroy bacteria H. Pylori bacteria burrow into the mucus layer to avoid the acid- can break thru stomach wall and cause ulcers

Eyes Tear glands produce tears that bathe surface of eye Enzyme called lysozyme destroys bacteria

Ears Wax traps bacteria and viruses Ear drum forms a complete barrier across the ear canal

Nose Hairs trap foreign particles Mucus layer also traps things, then they are either sneezed out or swallowed

Respiratory Tract Cells lining respiratory tract have CILIA- tiny hair-like structures that beat in unison to push foreign particles back up to the back of your throat, where they are swallowed

Respiratory epithelium: 1-cilia; 2-mucus cell

Urinary/Reproductive Tracts Vagina is slightly acidic, contains mucus Urethra is also acidic

Temperature Your body PURPOSELY elevates its temperature when you have an infection. Bacteria can only live at certain temperatures, so hopefully the elevated body temperature will kill them.

So what happens if a foreign invader makes its way into your body??? Blood clotting- stops up wounds in blood vessels, also helps prevent infectious agents from getting in Platelets block wound Fibrin protein forms scab Fibrin protein (green stuff)

ACTIVE IMMUNITY Your body’s acquired immune system Triggered by a specific attack by a specific pathogen Also called immune response White blood cells- key players in immune response

White blood cells can: Engulf and destroy pathogen Produce antibodies that destroy pathogens Produce antitoxins that neutralize toxins made by pathogens

White blood cell engulfing bacteria (what shape are these bacteria?)

White blood cells Recognize marker proteins on the surface of cells as our own (self) or foreign (nonself) These foreign markers are called ANTIGENS

Lymphocytes: T cells and B cells Produce antibodies against specific pathogens