Micropara lecture

• What is an immune system?

  • The body’s defense against disease causing

  organisms, malfunctioning cells, and foreign

  particles

  • Collection of cells and proteins that function

  to protect the skin, respiratory passages,

  intestinal tract and other areas from foreign

  antigens, such as microbes

  *The health of the body is dependent on the

  immune system’s ability to recognize and then

  repel or destroy these invaders.

  Most animals have systems that resist

  disease. The disease resistance

  provided by these systems is called

  Immunity

  • Two types:

  -innate

  -adaptive
• Innate/nonspecific immunity


  The body's first, generalized line of defense against all invaders
• Innate immune response


  • Furnished by barriers such as skin, mucus membranes, stomach acid, and saliva
  • Involves rapid inflammation of tissues
  • Consists of phagocytic cells, natural killer cells, antimicrobial proteins, and the inflammatory response
• These innate immune mechanisms hinder the entrance and spread of disease but can rarely prevent disease completely
• Skin


  The dead, outer layer of skin, known as the epidermis, forms a shield against invaders and secretes chemicals
• Role of skin


  • Dead skin cells constantly slough off, making it hard for invading bacteria to colonize
  • Sweat and oils contain anti-microbial chemicals, including some antibiotics
• Mucus


  • Contains lysozyme enzymes that destroy bacterial cell walls
  • The normal flow of mucus washes bacteria and viruses off of mucus membranes
  • Cilia in the respiratory tract move mucus out of the lungs to keep bacteria and viruses out
• Saliva


  • Contains many chemicals that break down bacteria
• Thousands of different types of bacteria can survive these chemicals
• Swallowed bacteria are broken down by incredibly strong acids in the stomach that break down your food
• The stomach must produce a coating of special mucus or this acid would eat through the stomach
• Phagocytes


  Several types of white blood cells (including macrophages and neutrophils) that seek and destroy invaders, and also destroy damaged body cells
• Phagocytes


  • Are attracted by an inflammatory response of damaged cells
• If invaders actually

  get within the body,

  then your white

  blood cells (WBCs)

  begin their attack

  • WBCs normally

  circulate throughout

  the blood, but will

  enter the body’s

  tissues if invaders

  are detected
• These white blood cells are

  responsible for eating

  foreign particles by

  engulfing them

  • Once engulfed, the

  phagocyte breaks the

  foreign particles apart in

  organelles called lysosome