Mass Transport

• High SA:V

  small organisms, rapid diffusion of gases across cell membrane, high metabolic rate, large heat loss, more energy needed to maintain body temp per unit of body mass
• Low SA:V

  large organisms, gas exchange system required, lower metabolic rate
• Haemoglobin structure

  quaternary protein made up of 4 polypeptide chain, containing 4 haem groups
• Where does hemoglobin associate to O2?

  gas exchange surfaces
• Where does haemoglobin dissociate with O2?

  At respiring tissues
• High affinity for O2


  take up O2 more easily

  release it readily
• Low affinity for O2

  take up O2 less readily

  release it more readily
• systole

  contraction of heart
• diastole


  relaxation of heart
• What happens during diastole

  blood flows into atrium
• atrial systole and ventricular diastole

  atria contracts and blood is pushed into the ventricle through the atrioventricular valves
• atrial diastole and ventricular systole


  ventricles contract and blood is pushed through the semi-lunar valves and out the heart
• To open valves

  pressure behind has to be greater that pressure in front
• To close

  pressure in front has to be greater than pressure behind
• double circulatory system

  blood passes through heart twice
• Artery structure

  Thick muscle layer-control volume blood

  Thick elastic layer- maintains high pressure and recoils to maintain flow

  Thick walls to resist bursting

  
• Arterioles structure

  Thicker muscle layer (than artery)-contracts to control blood flow into capillaries (vasoconstrict)

  Smaller collagen layer(than artery) as lower pressure

  
• Veins structure

  Thin elastic layer and collagen layer as low pressure

  Thin smooth muscle layer- prevent friction

  Valves- to prevent backflow

  
• Capillaries structure/function

  One cell thick

  lots- increases SA

  narrow-low blood pressure

  allows diffusion as one cell thick

  
• Bohr effect

  CO2 bind to haemoglobin and changes its shape, decreases its affinity for oxygen
• Small animal oxygen dissociation curve

  have a fast metabolism so need to have a low affinity for oxygen

  curve shifts right
• Llamas oxygen dissociation curve

  live in high altitudes so need to have a high affinity for oxygen

  curve shifts left
• Foetal haemoglobin oxygen dissociation curve

  O2 is needed from mothers blood so need to have a high affinity for oxygen

  curve shifts left
• Oxygen dissociation curve axis

  x-axis = partial pressure of oxygen in KPa

  y-axis = % saturation of haemoglobin with O2
• Why is the oxygen dissociation curve 'S' shaped?


  curve initially shallow as it is difficult for the first O2 molecule to bind

  curve steeps in the middle as haemoglobin changes shape and it is easier for 2nd and 3rd O2 to bind

  curve plateaus below 100% as it is difficult for 4th O2 molecule to bind
• Where is there a high ppO2?

  at gas exchange surface
• Where is there a low ppO2?

  at respiring tissues
• Oxygen dissociation curve left shift

  high affinity for oxygen
• Oxygen dissociation curve right shift

  low affinity for oxygen
• Tissue fluid


  A watery liquid that contains glucose, amino acids, fatty acids, ions in solution and oxygen. It supplies all of these substances to the tissues and receives carbon dioxide and other waste materials from tissues. It is the means by which materials are exchanged between blood and cells and bathes the cells of the body. It is formed from blood plasma.
• Formation of tissue fluid

  -Liquid leaves the plasma in the blood to form tissue fluid

  -Hydrostatic pressure at the arterial end is great enough to push molecules out of the blood in the capillary

  -Proteins remain in the blood, and the increased protein content creates a water potential between the capillary and tissue fluid

  -At the venule end, less fluid is pushed out as pressure within the capillary is reduced

  -The water potential gradient remains the same as in the arterial end so water begins to flow back into the capillary from the tissue fluid