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Animal Circulation

Animal Circulation. AP Biology Unit 6. Invertebrates with Gastrovascular Cavities. Don ’ t have a true circulatory system Material exchange (gases, nutrients, wastes) with the environment occurs through diffusion Why is diffusion effective here?

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Animal Circulation

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  1. Animal Circulation AP Biology Unit 6

  2. Invertebrates with Gastrovascular Cavities • Don’t have a true circulatory system • Material exchange (gases, nutrients, wastes) with the environment occurs through diffusion • Why is diffusion effective here? • The animals are only a few cell layers thick– materials don’t have to go across too many layers • Example: Cnidarians

  3. True Circulatory Systems • 3 main components in a true circulatory system: • Circulatory fluid (blood) • Tubes to transport fluid (blood vessels) • Muscular pump (heart)

  4. True Circulatory Systems • Blood pressure keeps the circulatory fluid moving through the system (in addition to other forces) • Blood pressure = force exerted on the walls of the blood vessels by the blood (caused primarily by the pumping of the heart)

  5. True Circulatory Systems • In general, higher metabolism means a more complex circulatory system • An animal either has an open or a closed circulatory system

  6. Open Circulatory Systems • Blood and interstitial fluid are the same (hemolymph) • Low blood pressure (less energy to circulate fluid) • Simple system of tubes • The heart helps pump hemolymph around • Hemolymph will also be pushed back into the tubes as the animal moves around

  7. Closed Circulatory System • Blood is confined to tubes, so it is different from interstitial fluid • Molecules diffuse between blood and interstitial fluid • High blood pressure

  8. Question… • Why would higher blood pressure be beneficial? • Can get blood to areas that need it more efficiently • Allows the organism to be more active

  9. Closed Circulatory System • Complex system of tubes • arteries = vessels that carry blood away from heart • veins = vessels that carry blood to heart • capillaries = tiny, porous vessels through which molecules diffuse in / out (throughout body)

  10. General Circulatory Pathway • Heart  artery  capillaries  vein  back to heart

  11. Comparison of Vertebrate Circulation • Gas exchange (CO2 and O2) with the environment across a variety of locations • Blood pressure is highest in the blood vessel leaving the heart

  12. Comparison of Vertebrate Circulation- Fish • Blood in the heart is separated (oxygenated and de-oxygenated blood are not mixed together) • Single circulation = blood goes to the heart once (continues on to the body without returning after the gills) • 2 chambers in heart (1 atrium, 1 ventricle)

  13. Comparison of Vertebrate Circulation- Amphibian • Blood in the heart is mixed– deoxygenated and newly oxygenated blood mix together in ventricle • Double circulation = blood is pumped two times from the heart– goes to the lungs, then comes back to get pumped to the rest of the body • 3 chambers in heart (2 atria, 1 ventricle)

  14. Comparison of Vertebrate Circulation- Reptile • Blood in the heart is mixed-- deoxygenated and newly oxygenated blood mix together in partially separated ventricle • Double circulation • 3 ½ chambers in heart (2 atria, one partially separated ventricle) • Only crocodiles have fully separated ventricles

  15. Reptile Circulation • Reptiles also have a 2nd aorta • Benefit? • Can bypass the lungs when underwater (no point in sending blood to the lungs if there can’t get O2 from them) • Blood continues to flow to the body tissues (so they can still get some O2)  higher activity

  16. Comparison of Vertebrate Circulation- Mammal & Bird • Blood is separated – held in separate chambers • Double circulation • 4 chambers in heart (2 atria, 2 ventricles)

  17. Question… • Why is having separated (compared to mixed blood) an advantage? • If blood is mixed, then deoxygenated blood that hasn’t gone to the lungs will also return to the body • Separated blood means that the blood returning to the body is all fully re-oxygenated

  18. Pressure and Metabolism • The inability to maintain pressure over a distance yields lower metabolism. • Pressure decreases as blood flows through tiny capillaries • Which organism can have the highest metabolic rate? • Mammals and birds (in general)

  19. Question… • What is the benefit of having double circulation (compared to single circulation)? • Blood can reach tissues more efficiently  High blood pressure • This allows the organism to be more active

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