Blood

• Plasma


  Liquid 55% of blood containing nutrients and wastes
• Components of blood


  • Plasma
  • Cells
• Blood cells


  • White blood cells
  • red blood cells
• Red blood cells


  • Made in bone marrow
  • Destroyed in spleen
  • Tiny to flow in narrow vessels
  • Biconcave disc in shape
• Hormones


  Regulate body functions
• Minerals


  Essential for body functions
• Red blood cells


  • Flexible
  • Can squeeze themselves
• Fibrinogen


  Protein involved in blood clotting
• Hemoglobin


  Carries oxygen
• Phagocytosis


  1. Contact

  2. Engulf

  3. Digest
• Blood


  Fluid that has different types of cells suspended in it, including red cells (RBCs), white cells (WBCs) and platelets floating in a liquid called plasma
• Plasma


  • Pale yellow liquid part of the blood (55%), mainly made of water and substances dissolved in it such as salt, proteins, nutrients, hormones, urea, oxygen gas and carbon dioxide
• Red blood cells (RBCs)

  • They contain haemoglobin, are tiny disc-like biconcave cells with an elastic cell membrane and no nucleus, providing a large surface area to absorb more oxygen
• White blood cells (WBCs)

  • They have an irregular shape and a nucleus, are fewer in number than RBCs but have important functions like engulfing and digesting bacteria and producing antibodies
• Platelets


  • Fragments of cells produced in the red bone marrow, contain an enzyme that helps to clot the blood at wounds and stop further bleeding
• There are 5 million RBCs per mm3 of blood, and each RBC lives for about 4 months with 200,000 million RBCs being replaced each day
• There are 7,000-8,000 WBCs per mm3 of blood, with WBCs being smaller in size than RBCs but less numerous (each WBC stands for 600 RBCs)
• There are 250,000 platelets per mm3 of blood
• Haemoglobin


  A red pigment found in the cytoplasm of RBCs, made of protein combined with iron, which enables RBCs to transport oxygen from the lungs to respiring tissues
• Oxygen transport by haemoglobin


  Haemoglobin combines with oxygen in the lungs to form unstable oxyhaemoglobin, which then breaks down and releases oxygen in respiring tissues
• Substances transported by blood

  • Oxygen from lungs to tissues
  • Carbon dioxide from tissues to lungs
  • Urea from liver to kidneys
  • Hormones from endocrine glands to target organs
  • Nutrients from small intestine to other body parts
  • Heat from liver and muscles to whole body