Transport in Humans

• Components of blood

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

  • Produced in the bone marrow
  • Destroyed in the Spleen & liver
  • Limited lifespan of 120 days
  • Filled with red pigment haemoglobin (essential for binding oxygen)
  • Absence of nucleus (allows more haemoglobin to be packed into the cell)
  • Biconcave shape
  • Increase surface area to volume ratio for efficient uptake of oxygen
• White blood cells

  • Larger than red blood cells
  • Fewer in numbers compared to red blood cells
  • Produced in the bone marrow
  • Destroyed in the spleen
  • Limited lifespan of a few days
  • Colorless as they do not contain haemoglobin
  • Irregular in shape and contain a mobile nucleus
  • Able to move, change their shape and squeeze through walls of thinnest blood capillaries
• Types of white blood cells

  • Lymphocytes
  • Phagocytes
• Lymphocytes


  • Produce antibodies to protect against microorganisms
  • Non-granular cytoplasm
  • Large Rounded Nucleus
• Phagocytes


  • Lobed nucleus
  • Granular cytoplasm
  • Able to engulf pathogens by phagocytosis
• Plasma

  • About 90% water, dissolves and transports:
  • Dissolved proteins such as fibrinogen, prothrombin and antibodies
  • Mineral salts
  • Electrolytes such as chlorides and sulfates of calcium and sodium
  • Nutrients substances such as glucose, amino acids and fats
  • Waste products such as urea, uric acid and creatinine
  • Hormones
• Process of Blood clotting

  1. Damaged tissues and platelets release an enzyme known as thrombokinase
  2. Thrombokinase converts prothrombin (inactive) to thrombin (active)
  3. Thrombin converts soluble fibrinogen to insoluble fibrin threads which entangle blood cells and form a clot

  Blood clotting only happens -> enough platelets & calcium
• Oxygen diffuses from the air sacs in the lungs into the blood, and haemoglobin combines with oxygen to form oxyhaemoglobin. Blood transports oxygen to all tissues of the body. At the tissue cells, oxyhemoglobin releases oxygen.
• Acclimatization

  • People living at high altitudes have increased number of RBC
  • Increases amount of haemoglobin
  • More oxygen transported per unit time
• Protective Function of Blood

  To protect the body against disease-causing organisms (pathogens)

  Clotting & Coagulation prevents entry of bacteria into the bloodstream and prevents excessive blood loss
• Transport Function of Blood

  To carry various substances from one part of the body to another

  [Oxygen, Heat, Hormones, Digested food substances, Excretory Products (Urea, Carbon Dioxide)]

  1. Blood passes through lungs, oxygen diffuses from the air sacs in the lungs into the blood
  2. Haemoglobin combines with oxygen to form oxyhaemoglobin
  3. Blood transports oxygen to all the tissues of the body
  4. At the tissue cells, oxyhaemoglobin releases oxygen

  Deoxygenated Blood -> Purplish Red

  Oxygen Rich Blood -> Bright Red
• Excretion vs Egestion

  Excretion is the removal of metabolic waste products (chemical reactions)

  Egestion is the removal of faeces (undigested food matter)
• Phagocytosis (P for Pacman)

  Phagocytosis is the process of engulfing, ingesting and digesting foreign particles (bacteria) by phagocytes
• Production of Antibodies (Y shape)

  Antibodies produced by Lymphocytes

  Binds to bacteria and causes surface membrane to rupture

  Bacteria Cells clump together in the presence of Antibodies

  Toxins produced by bacteria are neutralised by Antibodies

  Antibodies prevent viruses from binding to host cells

  
  

  Different from Antibiotics!

  Antibiotics are medicine used to treat bacterial infection

  "b" for bacterial

  Complete course of Antibiotics if not Antibiotic resistance
• Organ Transplant & Tissue Rejection

  Recipient may produce antibodies to reject/destroy transplant

  To reduce tissue rejection, have tissue/blood match & immunosuppressive drugs (stop production of WBC)
• Blood Groups 


  RBC have proteins called Antigens on their surfaces

  Plasma contains natural antibody which recognizes and binds to specific antigens on the RBC

  Antigens (uppercase) & antibodies (lowercase) opposite
• Agglutination or clumping of RBC

  Occurs when Recipient's and Donor's blood type don't match

  Solidification of RBC