1.2.4 Types of Circulatory System

Circulatory system can be classified into two types:

  1. closed circulatory system
  2. open circulatory system

Closed Circulatory System

  1. Usually found in large animals such as vertebrates.
  2. Medium of transport is blood
  3. The blood  flows continuously in blood vessels
  4. Exchange of gases, nutrients and waste products occurs between the blood in the capillary and the body cell.

    Open Circulatory System

    1. Usually found in smaller animals such as insects and shellfish.
    2. Medium of transport is haemolymph.
    3. Haemolymph is pumped from the heart into the cavity around the body cells.
    4. Exchange of nutrients and waste products occurs directly between  and the body cells the blood around it.
    5. The haemolymph  is then pumped back to the heart.

    Close Circulatory System vs Open Circulatory System

    Open Circulatory System Close Circulatory System
    Circulating fluid Haemolymph Blood
    Occurrence Small animals such as insects Large animals such as vertebrate
    Control of fluid flow Low level of control High level of control
    Presence of valve No Yes
    Pressure of circulating fluid Relatively low Relatively high