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


  Essential part of the immune system, defend against infection
• Functions of white blood cells

  • Phagocytosis (engulf and consume microorganisms)
  • Produce antibodies that bind to and help destroy pathogens
  • Produce antitoxins that neutralize toxins produced by pathogens
• White blood cells


  Have a nucleus, unlike red blood cells
• Platelets


  Small fragments of cells that float in the blood and help stop bleeding by clotting
• Plasma


  Pale straw-colored liquid that makes up over half the blood's volume, carries nutrients, waste products, hormones, antibodies, and toxins
• Most adults have about 5 liters of blood flowing through their circulatory system at any one time
• Artificial blood


  Blood substitute consisting of salt water, adds volume to the circulatory system but doesn't contain red blood cells so can only replace about 1/3 of the blood
• Blood transfusion


  Giving a person real blood donated by blood donors, which contains red blood cells to help survive blood loss