Open Circulatory System

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  1. Explain fluid.
    •                                                               i.      Hemolymph
    • 1.      Since fluid dumps into body cavities and sinuses, it mixes with interstitial fluid (fluid that bathes the cells)
    • a.      And so, it is indistinct from interstitial fluid cause it mixes with it
    • 2.      Function: transport of materials 
  2. Explain Vessels
    •                                                               i.      Vessels
    • 1.      Arteries and veins
    • a.      Open-ended
    •                                                                                                                                       i.      Arteries open at end
    •                                                                                                                                     ii.      Veins open at beginning
    • 2.      NO CAPILLARIEs
    • 3.      Exchange occurs at hemocoels, which are large cavities/ sinuses found throughout the body
  3. What are hemocoels?
    •                                                               i.      Hemocoels
    • 1.      Large cavities/ sinses found throughout the body
  4. Explain the pumping organ.
                                                                 1.      Heart; generates force to move hemolymph through the system
  5. Difference between open and closed in terms of heart?
    • 1.      One of the other major differences between open and closed is that the heart in an open system has holes called Ostia in it
    • a.      In addition to hemolymph entering heart through veins, it can also enter through ostia
  6. Ostia
    • 1.      Usually a sac around the heart, called pericardium (not same as vertebrates)
    • a.      You will see holes in the heart (the ostia)
    •                                                                                                                                       i.      Only in open circulatory system
    •                                                                                                                                     ii.      Strategically placed all throughout body so there is access to them
  7. Issues of this type:destination of material?
    •                                                               i.      issue is that it gets its push from the pumping organ, but the system is open-ended and dumps its material
    • 1.      Causes loss of pressure generated by pumping organ
    • a.      Very low pressure because you have open-ended vessels and lose the pressure when the arteries dump out into hemocoel
  8. Issues of this system: efficiency?
                                                                  i.      Very inefficient because the pressures are very low, particularly after they are dumped out in hemocoels
  9. Issues of this system: exchange?
                                                                  i.      EXCHANGE TAKES PLACE IN THE HEMOCOEL
  10. Issues of this type: rate
    •                                                               i.      Very slow
    • 1.      That’s why it’s found in very metabolically slow organisms
  11. Flow Chart
    • Heart--> arteries (High Oxygen)-->hemocoels:
    • O2 and CO2; nutrients given off to tissues and oxygen and anything else needed; dump in waste; exchange between tissues and circulatory system--> Veins (high CO2)--> respiratory hemocoels (CO2 dumped off and oxygen picked up) --> (2 destinations from here: either heart or more veins)--> heart where it dumps out
    • (other destination) respiratory hemocoels--> veins (high O2)--> pericardium (pericardial sinus)-->ostia-->heart
Card Set:
Open Circulatory System
2013-02-20 22:11:10
BIO 220 Test Two

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