Arterioles: Structure, Function, and Role in Blood Pressure Regulation

Structure of Arterioles

Arterioles are small arteries (10–100 µm diameter) with three layers:

• Tunica intima: Single layer of endothelial cells.
• Tunica media: Smooth muscle cells enabling vasoconstriction and vasodilation.
• Tunica adventitia: Connective tissue, fibroblasts, nerve fibers.

Key Functions

• Vasoconstriction/vasodilation: Controls vessel diameter, regulating blood pressure and flow distribution.
• Blood pressure regulation: Constriction raises pressure; dilation lowers it.
• Metabolic autoregulation: Adjusts flow to match tissue metabolic demand.
• Capillary exchange: Delivers blood to capillaries; diameter affects capillary pressure and exchange rate.

Arterioles are essential for blood pressure control, tissue perfusion, and substance exchange.