9.3b Circulatory system

• State the name of the 3 blood vessels.

  The three main types of blood vessels are arteries, veins, and capillaries.
• Describe the structure and function of the blood vessels.

  1. Arteries:

  - Structure: Thick walls with muscle and elastic tissue.

  - Function: Carry oxygen-rich blood away from the heart to the body.

  2. Veins:

  - Structure: Thinner walls with valves.

  - Function: Bring oxygen-depleted blood back to the heart from the body.

  3. Capillaries:

  - Structure: Very small, thin vessels.

  - Function: Exchange of gases and nutrients between blood and tissues.
• Link blood vessel structure to pressure changes

  Arteries have thick walls to handle the high pressure of blood pumped from the heart. Veins have thinner walls as they carry blood back to the heart under lower pressure. Capillaries, with their thin walls, allow for the exchange of substances between blood and tissues but can't handle significant pressure.
• State the three types of blood vessels

  The three types of blood vessels are arteries, veins, and capillaries.
• Describe the structure of each blood vessel.

  Arteries have thick, muscular walls. Veins have thinner walls with valves. Capillaries are tiny with thin walls.
• State the difference in pressure in each blood vessel.

  Pressure is highest in arteries, lower in veins, and lowest in capillaries.
• Why is pressure higher in arteries and lower in veins?

  Arteries have thick walls and elastic fibers to withstand the pressure of blood pumped from the heart. Veins have thinner walls as they carry blood back to the heart under lower pressure.
• Explain why veins need valves.

  Veins need valves to prevent the backward flow of blood due to low pressure and gravity, ensuring blood travels toward the heart efficiently.