The need for transport systems
# Substances that require transport
- Nutrients
- glucose—provide energy
- protein—growth and repair
- amino acids, fatty acids, glycerol
- Water
- Carbon Dioxide—removal post respiration
- Lactic acid—removal of waste
- Urea—removal of waste
- Hormones—chemical messaging
- Enzymes
# Open circulatory system
- Haemolymph instead of blood
- No veins, arteries or vessels, the haemolymph moves freely around the body
- Haemocoel—a central cavity that handles digestive and circulatory functions
- Organisms with an open circulatory system may still have a heart, or some form of pumping mechanism
- Low pressure
- Eg
- ant
- grasshopper
- stick insect
# Closed circulatory system
- Structured with veins, arteries and capillaries.
- High pressure
- Eg
- human
- frog
- bird
# Single circulatory system
- Blood passes the heart ONCE per cycle.
- Flow rate/pressure falls when blood leaves the gills or lungs.
- Low pressure blood inefficient for kidney function.
# Double circulatory system
- Blood passes the heart TWICE per cycle.
- Higher pressure.
- Kidney function is optimal.
# Keywords
- Systemic Circulation
- heart to body
- Pulmonary Circulation
- heart to lungs
See Structure of Heart for more details on transport