Arteriole

An arteriole is a blood vessel that extends and branches out from an artery and leads to capillaries.

Related Topics:
Blood - Vessel - Artery - Capillaries

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Arterioles have thick muscular walls and are the primary site of vascular resistance. The mean blood pressure in the arteries supplying the body is a result of the interaction between the cardiac output (the volume of blood the heart is pumping per minute) and the vascular resistance, usually termed total peripheral resistance by physicians and researchers.

Related Topics:
Muscular - Blood pressure - Cardiac output

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The up and down fluctuation of the arterial blood pressure is due to the pulsatile nature of the cardiac output and determined by the interaction of the stroke volume versus the volume and elasticity of the major arteries.

Related Topics:
Arterial - Cardiac output - Stroke volume

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The muscular contraction of arterioles is targetted by drugs that lower blood pressure (antihypertensives), for example the dihydropyridines (nifedipine and nicardipine), which block the calcium conductance in the muscular layer of the arterioles, causing relaxation. This decreases the resistance to flow into peripheral vascular beds, lowering overall systemic pressure.

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