circulatory systems

• what are the 2 types of circulatory systems

  open and closed
• which organisms have single circulatory systems

  fish
• which organisms have double circulatory systems

  mammals
• what are single circulatory systems

  blood only passes through the heart once for every complete circuit of the body
• what are double circulatory systems

  blood passes through the heart twice for every complete circuit of the body
• how does the circulatory system work in fish

  the heart pumps blood to the gills to become oxygenated and then on to the rest of the body then back to the heart
• how does the circulatory system work in mammals

  the right side of the heart pumps blood to the lungs to become oxygenated then from the lungs to the left side which pumps it to the rest of the body then back into the right side
• what is an advantage of double circulatory systems

  the heart can pump the blood at a higher pressure meaning a faster flow of blood
• which organisms have closed circulatory systems

  mammals and fish
• which organisms have open circulatory systems

  insects
• what are closed circulatory systems

  blood is enclosed inside blood vessels
• what are open circulatory systems

  blood isn't enclosed in blood vessels, instead it flows freely through the body cavity
• how do closed circulatory systems work

  the heart pumps blood in arteries which branch into many capillaries which substances diffuse out of into the body cells, but the blood stays inside the blood vessels as it circulates, blood returns to the heart by veins
• how do open circulatory systems work

  - The heart is segmented. it contracts in a wave, starting from the back, pumping the blood into a single main artery

  - The artery opens up into the body cavity

  - The blood flows around the insect's organs, gradually making its way back to the heart segments through a series of valves

  - The open circulatory system only provides the insect with nutrients and hormones, not o2, this is provided by tracheae
• how to do an external examination of a heart

  • feel inside the vessels to identify the 4 main vessels --> pulmonary artery, aorta, vena carva and pulmonary vein
  • identify the right and left atria and ventricles and the coronary artery
• how to dissect a heart for an internal examination?

  • use a scalpel to make a cut from the base to the top, along the left ventricle
  • repeat on the right ventricle to expose the inner chambers
  • identify the AV and semilunar valves
  • observe the thickness of the ventricular walls
  • identify the septum