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Transport In Animals

TRANSPORT IN ANIMALS    

Circulatory Systems

OPEN CIRCULATORY SYSTEM-

  • In invertebrates (e.g. insects), blood isn’t held within vessels always
  • It’s free to circulate the body cavities (spaces)
  • Only works for insects because they’re small
  • Cannot contain any pressure, blood pressure is low, blood flow is slow, not directed to particular organs and wouldn’t meet demand of large animals

 

CLOSED CIRCULATORY SYSTEM-

  • In vertebrates (e.g. fish & mammals), blood is never released into the body cavity
  • Blood circulates through series of blood vessels- artery, vein, capillary
  • Blood can be pumped under pressure, blood flows quickly, can be directed to specific organs
  • More responsive to changes in demand e.g. by increasing pressure to carry more oxygen
  • Dilate and constrict vessels to other organs

 

Single and double circulatory systems:

  • In a single circulatory system, blood flows through the heart once in one circuit
  • In a double circulatory system, blood flows through the heart twice in one circuit (CIS 1.6)