Arteries: carry blood from heart to the rest of the body. They have strong muscular walls.
Veins: carry blood from the rest of the body to the heart. They have elastic walls
Capillaries: allows substances to pass through cells or viceversa. They are very thin
Arteries
Annotations:
Blood in the arteries is under high pressure generated by the heart. The arteries have:
1.thick outer walls
2. thick layers of muscle and elastic fibres.
Veins
Annotations:
The blood in veins is under lower pressure than the blood in arteries. The veins have:
1. thin walls
2. thin layers of muscle and elastic fibres.3. Unlike arteries, veins have one-way valves in them to keep the blood moving in the correct direction.
Capillaries
Annotations:
The function of capillaries is to allow food and oxygen to diffuse to cells while waste is diffused from cells. Capillaries have thin walls - only one cell thick
Blood
Annotations:
It transports: nutrients, oxygen, CO2, waste products (urea), hormones, etc.