transport in humans and plants

• Blood


  Transports substances around the body and defends it against disease
• Main components of blood


  • Plasma
  • RBC
  • WBC
  • Platelets
• Plasma


  Yellowish liquid in blood, contains mainly water and substances such as glucose, salts, proteins, amino acids, fats, vitamins, hormones, and metabolic waste such as urea, also contains RBCs & WBCs
• Function of plasma


  1. Transports blood cells around the body

  2. Transports nutrients from small intestine to other parts of the body

  3. Transports metabolic waste products from organs where they were produced to organs such as the kidneys and lungs for removal

  4. Transports hormones from endocrine glands to target organs
• Platelets


  Fragments of cytoplasm, contain an enzyme that catalyses the conversion of fibrinogen to fibrin threads
• Red Blood Cells (RBCs)

  Circular, biconcave shape, no nucleus, contains red pigment haemoglobin, flexible
• Adaptations of RBCs

  • Contain haemoglobin, can combine reversibly with oxygen, in lungs oxygen concentration is high so haemoglobin binds with oxygen to form oxyhaemoglobin, in tissues oxygen concentration is low so oxyhaemoglobin releases oxygen to tissue cells
  • Biconcave shape increases surface area to volume ratio, rate of absorption and release of oxygen
  • Flexible, can change into bell shape structure, can flow easily through narrow blood capillaries
  • No nucleus, more space for haemoglobin to be stored
  • Old and worn out RBCs are destroyed in the spleen and liver
• Function of RBCs:

  • transport oxygen from lungs to other parts of the body