Blood Vessels

Question 1

What are the three different types of blood vessels?

Answer 1

• ARTERIES - these carry blood AWAY from the heart.
• CAPILLARIES - these are involved in the EXCHANGE of MATERIALS in the cells.
• VEINS - these carry blood TO the heart.

Question 2

Describe the arteries.

Answer 2

• The heart pumps out blood at HIGH PRESSURE so the artery walls are STRONG and ELASTIC
• The ELASTIC FIBRES allow arteries to EXPAND.
• The walls are THICK compared to the LUMEN. They contain, thick layers of muscle to make them STRONG
• The largest artery I the body is called the AORTA

Question 3

Describe a. CAPILLARY

Answer 3

• Arteries branch into capillaries
• capillaries are really tiny - too small to see
• they carry the blood really close to every cell in the body to EXCHANGE SUBSTANCES with them
• they have PERMEABLE walls, so substances can DIFFUSE in and out
• they supply FOOD and OXYGEN, and take away WASTES like CARBON DIOXIDE (CO2)
• Their walls are usually ONLY ONE CELL THICK. This INCREASES the rate of diffusion by DECREASING the DISTANCE over which it happens.

Question 4

Describe VEINS

Answer 4

• Capillaries eventually join up to become veins
• The blood is at a LOWER PRESSURE in the veins so the walls don’t need to be as thick as artery walls
• They have a BIGGER LUMEN than arteries to help the blood flow despite the lower pressure
• They also have VALVES to help the blood flow in the right direction
• the LARGEST VEIN in the body is called the INFERIOR VENA CAVA (IVC)