Transport systems

• Why do large multicellular organisms need transport systems?

  
  

  Size, small SA:V, high metabolic rate

  • SA:V is usually low
  • Need to maintain steep concentration or diffusion gradient
  • Diffusion distance is too large/diffusion is too slow
  • Therefore diffusion not sufficient for an organism's survival
  • Waste needs to be removed from cells
  • Metabolites needed by cells
  • Need large or rapid oxygen supply
  • High metabolic demands
• Differences between a single and double circulatory system?

  SINGLE:

  • Blood travels once through the heart for each complete circulation of the body
  • blood pumped under low bp
  • Blood passes through two sets of capillaries
  • Lower efficiency
  • Heart has one atria and ventricle

  DOUBLE:

  • Blood travels twice through the heart for each circulation of the body
  • Blood pumped under high pressure
  • Blood passes through one capillary network
  • Higher efficiency
  • Heart has 2 atria and ventricles
• Differences between open and closed circulatory systems?

  OPEN-

  • No vessels for transport medium
  • deoxy and oxy blood mix- less efficient
  • Pumped straight from heart into body cavity (haemocel)
  • Pumped under low bp 
  • Blood flows slow 
  • Insect transport medium is haemolymph
  • haemolymph comes into direct contact with body cells

  CLOSED-

  • Blood enclosed in vessels
  • deoxygenated and oxygenated blood don't mix- more efficient
  • Pumped under high bp
  • Blood flows quick 
  • Transport medium is blood
  • blood doesn't come into direct contact with body cells
• what is another term for circulatory systems?

  mass transport systems
• what are the three things common in all circulatory systems?

  • liquid transport medium to transport substances
  • vessels for transport medium
  • pumping mechanism (heart)
• what is the open body cavity of an animal with an open circulatory system referred to as?

  haemocel
• what kind of animals are open circulatory systems found in?

  invertebraes
• what is insect blood called?

  haemolymph
• what are the properties of haemolymph?

  • doesn't carry oxygen or carbon dioxide
  • transports food, nitrogenous waste products and cells for fighting against disease
  • steep diffusion gradients cannot be maintained for the most effective diffusion
  • amount of haemolymph flowing to a tissue can't be varied to meet changing demands
• explain how blood travels through single-closed circulation

  • two sets of capillaries- in the first, carbon dioxide and oxygen exchanged between cells and blood
  • in the second, substances exchanged between blood vessels and cells
• why is blood pumped under such a low pressure in single circulatory systems?

  • passes through very narrow capillary networks
  • blood returns to heart slow
  • limits efficiency of exchange so animals with this system have low activity levels
• what animal is an exception to inefficiency while having a single circulatory system? (CCS)

  • bony fish- because of the efficiency of counter-current flow maintaining steep concentration gradients