F211- Transport in animals

Large animals and transport systems

• All living cells need a supply of oxygen and nutrients to survive, they also need to remove waste products.
• Small organisms dont need a seperate transport system because all their cells are in close contact with the environment therefore diffusion will suppy enough O2 and nurtrients
• 

Three main factors that affect the need for a transport system are:

• Size
• Surface area to volume ratio
• Level of activity

Features of a good transport system:

• A fluid or medium to carry nutrients and oxygen around the body- this is the blood  
•  
• A pump to create pressure that will push the fluid around the body- this is the heart  
• Exchange surface that will allow oxygen and nutrients to enter the blood

Single and Double Circulatory system

Fish have a single circulatory system.  Heart -> Gills -> Body -> Heart

Single and Double Circulatory system

Mammals have a double circulatory system

• This involves two seperate circuits. One carries blood to the lungs to pick up oxygen this is pulmonary circulation. The other carries the oxygen nutrients around the body to the tissues this is the systmetic circulation Heart -> Body -> Heart -> Lungs