Difference types of circulatory systems

• what is an open circulatory system?

  a circulatory system with a heart but few blood vessels to contain the transport medium
• what is a closed circulatory system?

  a circulatory system where the blood is contained within blood vessels or heart chambers, and does not come into direct contact with cells or the body outside of blood vessels
• what is haemolymph?


  transport medium in an insect (same role as blood)
• what is haemocoel?


  a body cavity in an insect
• how does a circulatory system work?

  • haemolymph enters the heart through pores called ostia
  • heart pumps haemolymph towards the head by penstalsis
  • in some larger insects there are ended tubes attached to the end of the heart, which can direct towards active part of insect, such as leg
  • haemolymph pours into haemocoel (body cavity)
• what system do insects use?

  open system
• what system do larger animals use?

  closed system
• what are advantages of an open circulatory system?

  • uses less energy (low metabolic rate)
• what are advantages of closed single circulatory system?

  • can transport substances to specific cells and tissues around the body - always taking blood to specific areas
  • can redirect blood to more active tissue
  • higher pressure so more efficient than open so fish can be much larger in size than insects
• what are disadvantages of an open circulatory system?

  • can't transport substances in haemolymph to specific cells/tissues
  • lower pressure makes it inefficient - limits the maximum size of insects
• what are disadvantages of a closed single circulatory system?

  • higher metabolic level (need more energy)
• what is a single circulatory system?

  • a circulatory system where the blood flows through the heart and is pumped out to travel all around the body before returning to the heart
  • in fish and annelid worms
  • 2 chambers
• what is a double circulatory system?

  • a circulatory system where the blood travels twice through the heart for each complete circulation of the body
  • in the first circulation blood is pumped by the heart to the brain and body to supply cells with oxygen
  • mammals and birds
  • 4 chambers
• what are disadvantages of a single circulatory system?

  • less efficient for larger animals - substances won't be pumped around fast enough to meet requirements of animals
  • low pressure from gills to body tissues means a lower rate of oxygen delivery
• why is a single circulatory system is sufficient for fish?

  • small enough size means that it doesn't need a complex transport system
  • lower energy requirements - lower oxygen requirement
  • fish are ectotherms ('cold blooded') - meaning they don't regulate their body temperature using their metabolism
• what does endothermic mean?

  internally regulate body temperature (humans)
• what are advantages of a double circulatory system?

  • high pressure allows for fast efficient exchange of substances that meet the requirements of larger animals - higher rate of oxygen delivery
• why do mammals require a double circulatory system?

  • larger animals have larger energy requirements and oxygen requirements
  • mammals are endotherms - meaning they regulate their body temp using their metabolism
• why is it important that the systemic circuit is at higher pressure than the pulmonary circuit?

  • systemic circuit has to pump blood further
  • too high pressure in pulmonary circuit may cause damage to the capillaries around the alveoli