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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
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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
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What are hemocoels?
- i. Hemocoels
- 1. Large cavities/ sinses found throughout the body
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Explain the pumping organ.
1. Heart; generates force to move hemolymph through the system
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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
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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
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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
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Issues of this system: efficiency?
i. Very inefficient because the pressures are very low, particularly after they are dumped out in hemocoels
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Issues of this system: exchange?
i. EXCHANGE TAKES PLACE IN THE HEMOCOEL
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Issues of this type: rate
- i. Very slow
- 1. That’s why it’s found in very metabolically slow organisms
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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
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