| What are the 3 types of blood vessels and whats their function | Arteries, They carry the blood away from the heart
Veins, They carry the blood towards the heart
Capillaries, They exchange substances in the tissues. |
| How are arteries made and adapted? | They pump blood away at high pressures. The walls are therefore elastic and strong which covers the lumen [the hole]
Their muscle has many thick layers for strength and elastic fibres to stretch and spring back.
They can also branch into arterioles. |
| How are Capillaries made and adapted? | They come from the Arterioles branches which make them really small. In tissues, the network of those capillaries are called capillary beds. They carry the blood really close to each cell to exchange materials [eg Oxygen for Carbon Dioxide]
Capillaries have permeable walls, which allows diffusion
They are one cell thick, which increases massively the ratio for surface area to volume.
They can be branched to Venules. |
| How are Veins made and adapted? | Veins are formed from the joint up Venules. Blood pressure here is lower so the walls are not as thick. They do however have a larger lumen to help the blood flow. They also have valves, to ensure the direction of the blood to the heart. |
| How does cross section area of vessels affect the blood flow? | When the cross section increases, the velocity of the blood decreases. So capillaries slow it down not for a bad reason, but a good one. In the capillary beds, the blood flow is slow which allows the exchange of materials. If it had the same velocity as arteries, nothing would be diffuesed.
Artieries have the highest velocity as its closer to the heart. |
