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 scabFibrin 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