Adaptations for transport in animals

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  • Created by: zoolouise
  • Created on: 03-05-16 20:07

Adaptations for transport in animals

Features of a transport system

Animals have the following features:

  • A suitable medium to carry materials
  • A pump, e.g. the heart which moves the blood
  • Valves to maintain the flow in one direction

Some systems also have:

  • A respiratory pigment, e.g. haemoglobin which allows a higher volume of oxygen to be transported
  • A system of vessels with a branching network to distribute the transport medium to all parts of the body

Open circulatory systems

  • Blood doesn't move around the body in blood vessels, it bathes the tissue directly
  • Blood is held in a cavity which is called the haemocoel and it's found in insects
  • They have a long, dorsal, tube-shaped heart which runs the length of the body
  • It pumps blood at lower pressure into the haemocoel
  • Here materials are exchanged between the blood and body cells
  • The blood slowly returns to the heart and the open circulation stars again
  • Oxygen diffuses directly into the tissues from the tracheae so blood doesn't transport oxygen and has no respiratory pigment

(http://i66.tinypic.com/2wem8ls.jpg)

Closed circulatory systems

The blood moves in blood vessels. There are two types of closed systems: single circulation and doule circulation.

Single circulation

  • Blood moves through the heart once in its passage around the body. e.g. in the earthworm
  • Blood moves forward in the dorsal vessel and back in the ventral vessel
  • Five pairs of pseudohearts, thickened, muscular blood vessels, pump the blood from the dorsal to the ventral vessel and keep it moving 
  • e.g. fish. The ventricle of the heart pumps deoxygenated blood to the gills, where its pressure falls
  • Oxygenated blood is carried to the tissues
  • From there, deoxgenated blood returns to the atrium of the heart
  • Blood moves to the ventricle and the circulation starts again

Double circulation

  • Blood passes through the heart twice in its circuit around the body 
  • e.g. mammals:
  • Blood is pumped by a musclar heart at a high pressure and this gives a rapid flow rate through the vessels
  • Organs aren't in direct contact with the blood, they're bathed in tissue fluid
  • This seeps out of capillaries
  • They have a blood pigment - haemoglobin which carries oxygen
  • When blood…

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