Structure
Arteries:

 

  • Carry blood from the heart to the rest of the body
  • Their cell walls are made up of layers, all of which are used to maintain the pressure of the blood
  • They an elastic layer which can stretch to ensure that the arteries do not burst under the high pressure of the heart
  • All arteries, except for the pulmonary artery, carries oxygenated blood

 

Arterioles

 

  • Carry blood from the arteries to more specific regions of the body
  • They an elastic layer which can stretch to ensure that the arteries do not burst under the high pressure of the heart
  • They can control the rate of blood going into certain regions through constriction or dilation of the muscle layers.

 

Veins

 

  • Carries blood from the body back to the heart
  • They are under low pressure with wider lumens compared to the arteries.
  • They do little elasticity or muscle layer.
  • Muscle contractions from muscles around the veins encourages deoxygenated blood to be pushed back towards the heart
  • The veins contain valves that prevent backflow

 

Capillaries

 

  • Carries blood from the arterioles to the cellular level to exchange the contents, i.e. oxygen, into the tissue fluid.
  • They have walls which are only one cell thick therefore decreasing the diffusion pathway
  • There is a large network of capillaries to increase the surface area for exchange. Lots of capillaries together in a network are called capillary beds

 

The Walls of Veins and Arteries

 

  • Tough Fibrous: Both of the veins and the arteries have equal sized outer layers. The particular presence of the outer layer maintains the pressure of the artery so it cannot rupture
  • Muscle Layer: The muscle layer is thicker in the arteries and can be constricted and dilated in order to control the volume of blood within
  • Elastic Layer: The Elastic layer is ticker in the artery and is used to deal with the high pressure from the heart.
  • Valves are only found in the veins to prevent backflow from the reduction in pressure
  • The lumen is larger in the veins compared to the arteries