blood

• Main components of blood

  • Red blood cells
  • White blood cells
  • Platelets
  • Plasma
• Red blood cells


  Carry oxygen from the lungs to the body's tissues
• Red blood cells


  • Don't have a nucleus, which means more space for hemoglobin and oxygen
  • Shaped like a biconcave disc, which gives them a large surface area for absorbing oxygen
• White blood cells


  An essential part of the immune system, which defends against infection
• How white blood cells defend against pathogens

  • Phagocytosis (engulfing and consuming microorganisms)
  • Producing antibodies that bind to and help destroy pathogens
  • Producing antitoxins that neutralize toxins produced by pathogens
• Platelets


  Small fragments of cells that float in the blood and rush to wounds to help stop bleeding and prevent infection
• Plasma


  The pale, straw-colored liquid part of the blood that carries various substances, including red blood cells, white blood cells, and platelets
• Most adults have about 5 liters of blood flowing through their circulatory system at any one time
• Artificial blood


  A blood substitute that consists mainly of salt water, which can add volume to the circulatory system but does not contain red blood cells to transport oxygen
• Blood transfusion


  Giving a person real blood that has been donated, which contains red blood cells to help survive blood loss