Circulatory system can be classified into two types:
- closed circulatory system
- open circulatory system
Closed Circulatory System
- Usually found in large animals such as vertebrates.
- Medium of transport is blood
- The blood flows continuously in blood vessels
- Exchange of gases, nutrients and waste products occurs between the blood in the capillary and the body cell.
Open Circulatory System
- Usually found in smaller animals such as insects and shellfish.
- Medium of transport is haemolymph.
- Haemolymph is pumped from the heart into the cavity around the body cells.
- Exchange of nutrients and waste products occurs directly between and the body cells the blood around it.
- 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 |