transport through blood

• only 3% of oxygen is carried in a solution in the blood plasma as oxygen is not very soluble in water
• 97% is carried in combination with haemoglobin molecules in rbc
• Haemoglobin + oxygen <--> oxyhaemoglobin
• Haemoglobin increase oxygen-carrying capacity by 60-70 times
• Oxygen combines w haemoglobin when concentration is relatively high like in the capillaries in the lungs
• Oxyhaemoglobin breaks down when concentration of oxygen is relatively low, giving up the oxygen to body cells when flowing through capillaries
• Rbc are well suited to carry oxygen because : 

  • contains haemoglobin which can combine with oxygen 
  • have no nucleus meaning there is more room for haemoglobin molecules
  • have a biconcave disc shape with the biconcave centre increasing surface area for oxygen exchange. the thicker edges increases volume allowing for more room for haemoglobin
• 8% of carbon dioxide is dissolved in plasma and carried in a solution
• carbon dioxide can diffuse out of blood
• 22% of carbon dioxide combines with the globin forming carbaminohaemoglobin which breaks down to release the carbon dioxide, allowing it to diffuse out
• 70% is carried in plasma as bicarbonate ions
• carbon dioxide + water <--> carbonic acid <--> hydrogen ion + bicarbonate ion
• in the capillaries around normal body cells, carbon dioxide reacts with water to create carbonic acid. the carbonic acid ionises into hydrogen ions and bicarbonate ions
• in the capillaries around alveoli, hydrogen ions and bicarbonate ions recombines to form carbonic acid, enzymes break the carbonic acid into water and carbon dioxide allowing the carbon dioxide to diffuse
• nutrients and waste is transported by being dissolved in plasma
• Inorganic nutrients are transported as ions like (Na+, K+, Cl-)
• organic nutrients that are transported by plasma includes glucose, vitamins, amino acids
• metabolic wastes are substances produced by cells that cannot be used and that would be harmful if allowed to accumulate
• metabolic wastes like urea, creatinine, uric acid are transported through the plasma