immune system

• Immune System


  Body's defense against disease causing organisms, malfunctioning cells, foreign particles
• First Line of Defense


  • Skin
  • Mucus and Cilia
  • Saliva
  • Stomach Acid
• Skin


  • Epidermis is the dead, outer layer
  • Forms a shield and secretes chemicals that kill potential invaders
  • 40,000 – 50,000 skin cells are shed everyday
• Mucus and Cilia


  • Particles and bacteria bump and get stuck in the mucus throughout the respiratory system
  • Hair like structures of cilia sweep this mucus into the throat for coughing or swallowing
• Saliva


  • Contains chemicals that break down bacteria
• Stomach Acid


  • Swallowed bacteria are broken down
  • Stomach produces a mucus coating for the acid not to eat through
• Food is digested in the tube hole but never enters into the solid plastic material
• Tube inner surface: digestive system
• Tube outer surface: skin
• Plastic interior: body
• Escharichia Coli


  • An invader or E.Coli
  • Common and many in digestive tracts
  • These bacteria are outside the body and aid in digesting material we cannot
  • If introduced in an unnatural manner, it can break thru first line of defense and harm us
• Second Line of Defense


  • White Blood Cells
  • Phagocytes
  • T-Cells
• White Blood Cells


  • Attacks invaders if they enter the body
  • Circulate in the blood but enters body tissues if invaders are detected
• Phagocytes


  • Type of WBC responsible for eating foreign particles by engulfing them
  • Breaks apart particles in organelles called lysosomes
• 1. Cells


  • Type of WBC
  • Or natural killer cells that recognize infected and cancer cells
  • Attacks the infected cells, kills them quickly and searches for more cells to kill
• Interferon


  • Virus infected body cells release this when an invasion occurs
  • Chemical that interferes with viruses that attack body cells
• Inflammatory Response


  • Triggered by histamines, chemicals that the injured body cells release
  • Capillaries dilate
  • Pyrogens released, reach hypothalamus, temp rises
  • Pain receptors activate
  • WBCs flock to infected area
• Viruses


  • An invader
  • Enters the body, hijack organelles, turns the cell into a virus making factory
  • The cell will eventually burst, releasing viruses to infect new cells
• Divisions


  • Cell Mediated
  • Antibody Mediated
• Cell Mediated


  • Efforts of WBCs or phagocytes and T-cells
  • Protective factor = living cells
  • Phagocytes eat invaders, t cells kill invaders
• Antibody Mediated


  • Controlled by antibodies
  • 3rd line of defense
• Third Line of Defense


  • Antibodies
• Antibodies


  • Triggered by infections that make it past the first and second line of defense
  • Proteins latch onto, damage, clump, slow foreign particles
  • Each binds only to 1 antigen which is a specific binding site
• Antibody Production


  1. WBCs gobble up invading particles and break them up

  2. WBCs show the particle pcs to T cells who will identify the pcs and find specific b cells to help

  3. B cells produce antibodies equipped to find that specific pc on a new particle and attach
• Immunity


  Resistance to a disease causing organism or harmful substance
• Situational Immunity


  • NEW particles take longer to identify, and a person remains sick until a new antibody can be created
  • OLD particles are quickly identified, and a person may never become ill from that invader again, this person is now immune
• Active Immunity


  • You produce the antibodies
  • Your body was exposed to the antigen thru: Exposure to disease causing antigen – you fought it, won, remember
  • Or planned exposure to a killed or weakened antigen – you detected it, eliminated, remember
• Vaccine


  • Antigens are deliberately introduced in immune system to produce immunity
  • Bc bacteria was killed or weakened, minimal symptoms occur
  • Resulted to eradicated diseases like polio and smallpox
• Passive Immunity


  • You don't produce the antibodies
  • A mother passes immunities to the baby during pregnancy through the placenta
  • The endocrine gland responsible to release antibodies that will protect the baby only after its birth while developing its immune system is thymus
  • Lasts until antibodies die