Compare the roles of respiratory, circulatory and excretory systems

1

• Compare the roles of respiratory, circulatory and
  excretory systems

Respiratory System The respiratory system
enables gaseous exchange to occur between an
organism and its external environment. Organisms
take in oxygen which is essential to keep alive
and remove carbon dioxide as it can becomes toxic
if present in large quantities. The organs
responsible differ between animals as mammals
have lungs and fish have gills.
2

• Circulatory (transport) System
• A transport system ensures that all cells in an
  organism are supplied with necessary nutrients
  and gases as well as removing waste.
• The circulatory system transports gases eg oxygen
  and carbon dioxide, nutrients, waste products,
  hormones and antibodies. It is responsible for
  maintaining a constant internal environment ie pH
  and osmotic pressure. The circulatory system also
  removes any toxins or pathogens and is
  responsible for the distribution of heat.

3

• Excretory System
• The excretory system is responsible for removing
  metabolic wastes from the blood and to expel them
  from the organism.
• Two main waste products are
• Nitrogenous wastes excreted as part of urine
• Carbon dioxide expelled from the lungs
• Excretory system is closely linked to water
  balance in an organism. The more toxic the waste,
  the greater amount of water is needed to dilute
  it for excretion.
• Some organisms also use the excretory system to
  eliminate excess salts, regulate pH of body
  fluids and blood pressure.