The beginning of a true capillary is surrounded by a precapillary sphincter. The opening and closing of precapillary sphincters is controlled by . The beginning of a true capillary is surrounded by a precapillary sphincter. The opening and closing of precapillary sphincters is controlled by . parasympathetic nervous system blood pressure in the metarteriole sympathetic nervous system local chemical conditions

Local chemical conditions

Explanation: A Precapillary Sphincter is a smooth muscle that is located in circles around the capillaries.

The precapillary sphincter helps to coordinate blood flow to the into the capillaries by causing the capillaries to decrease the flow of blood to tissues that are dormant or not active.

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