blood

• Red blood cells


  Blood cells that carry oxygen from the lungs to the body cells.

  Biconcave disc shape to have high surface area

  Large surface area for absorbing oxygen

  No nucleus - more room to carry oxygen

  Contain red pigment (Haemoglobin) in the lungs, haemoglobin binds to oxygen to become oxyhemoglobin, in the body tissues, the reverse happens, releasing oxygen to the cells
• White blood cells


  Defend against infection

  Some are phagocytes which can engulf microorganisms

  Others produce antibodies and antitoxins

  They do have a nucleus
• Platelets


  Small fragments of cells (no nucleus)

  Help blood clot at a wound to stoop microorganisms from getting in

  Lack of platelets can cause excessive bleeding and bruising
• Plasma


  Liquid that carries everything in the blood

  - Red, white blood cells and platelets

  - Nutrients like glucose and amino acids

  - Carbon dioxide

  - Urea

  - Hormones

  - Proteins

  - Antibodies and antitoxins
• Blood is a tissue consisting of plasma, in which the red blood cells, white blood cells and platelets are suspended
• What do red blood cells do

  carry oxygen from the lungs to the body cells
• Why do red blood cells have a biconcave disc

  to increase surface area, a large surface area is needed for absorbtion of oxygen
• Why do red blood cells have no nucleus

  To have more room to carry oxygen
• Why do red blood cells contain red pigment

  they contain red pigment (Haemoglobin) in the lungs, haemoglobin binds to oxygen to become oxyhemoglobin, in the body tissues, the reverse happens, releasing oxygen to the cells