Immunity

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Immunity

• Your bodys defense against infection!

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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

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Passive Immunity (innate immunity)

• Structures that are there already (because of
  your genes) that protect you from foreign invaders

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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

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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
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Eyes

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

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Ears

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

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Nose

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

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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

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Urinary/Reproductive Tracts

• Vagina is slightly acidic, contains mucus
• Urethra is also acidic

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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.

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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)
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ACTIVE IMMUNITY

• Your bodys acquired immune system
• Triggered by a specific attack by a specific
  pathogen
• Also called immune response
• White blood cells- key players in immune response

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White blood cells can

• Engulf and destroy pathogen
• Produce antibodies that destroy pathogens
• Produce antitoxins that neutralize toxins made by
  pathogens

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

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

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Lymphocytes T cells and B cells

• Produce antibodies against specific pathogens