Arterioles

• Arteries branch into arterioles which are smaller and form a network throughout the body
• Arterioles can contract to restrict blood flow and relax to increase blood flow

  • This allows blood to be directed to different areas according to demand
• Arterioles structure: Muscle layer is thicker than in arteries

  • The contraction of this muscle layer allows constriction of the lumen of the arteriole
  • This restricts the flow of blood and so controls its movement into the capillaries that supply the tissues with blood
• Arterioles carry blood, under lower pressure than arteries, from arteries to capillaries. They also control the flow of blood between the two
• Arterioles structure: Thinner elastic layer than arteries

  • Because blood pressure is lower