Veins

• Veins - Carry blood towards the heart
• Veins adaptations: Wider lumen

  • As blood is at low pressure
• Veins structure: Valves

  • Ensure blood does not flow backwards (might as pressure is low)
• Veins structure: Thinner muscle layer than arteries

  • Carry blood away from tissues, and therefore there constriction and dilation cannot control the flow of blood to the tissues
• Veins:

  • When skeletal muscles contract they compress veins, helping to increase pressure and push blood along
• Veins transport blood slowly, under lower pressure, from the capillaries in tissues to the heart
• Veins structure: Thinner elastic layer than arteries

  • The low pressure of blood within the veins will not cause them to burst, and pressure is too low to create a recoil action
• Veins structure: Thin walls

  • No need for a thick wall as the pressure within the veins is too low to create any risk of bursting
  • Also allows them to be flattened easily, aiding the flow of blood within them