Lecture Notes: Arteries

Overview

• Three Groups of Arteries:
  1. Elastic Arteries
  2. Muscular Arteries
  3. Arterioles
• Groups are categorized by size and function.

Elastic Arteries

• Characteristics:
  • Thick-walled and closest to the heart, particularly near the aorta and major branches.
  • Referred to as conducting arteries.
  • Large lumen, contributing to low resistance.
• Structure:
  • Contains elastin in all three layers (tunics), especially in the tunica media.
  • Has some smooth muscle but not involved in vasoconstriction; active in vasodilation.
• Function:
  • Act as pressure reservoirs by expanding and recoiling with blood ejection.
  • Ensure continuous blood flow downstream, even between heartbeats.

Muscular Arteries

• Characteristics:
  • Also known as distributing arteries.
  • Intermediate size: ranges from size of a pinky to pencil lead.
  • Most named arteries in lab are muscular arteries.
• Structure:
  • Thickest tunica media with more smooth muscle.
  • Less elastic tissue compared to elastic arteries.
• Function:
  • Active in vasoconstriction (reducing lumen diameter).

Arterioles

• Characteristics:
  • Smallest arteries with a lumen size from 0.3 mm to 10 micrometers.
• Structure:
  • Larger arterioles have all three tunics; primarily smooth muscle with some elastic fibers.
  • Smaller arterioles lead to capillary beds and are mostly a single layer of smooth muscle.
• Function:
  • Control flow into capillary beds via vasodilation and vasoconstriction.
  • Known as resistance arteries due to ability to change resistance by altering diameter.
• Importance:
  • Feed into capillary beds and regulate blood flow to tissues.

Summary Recap

• Elastic Arteries: Closest to the heart, act as pressure reservoirs.
• Muscular Arteries: Follow elastic arteries, active in vasoconstriction, distribute blood to organs.
• Arterioles: Smallest, control blood flow into tissues by feeding into capillary beds.