Melasma Overview. Patches of melasma are darker than other areas of skin because they have more pigment. The cells that produce pigment in the skin are called melanocytes. Ultraviolet radiation, or UV rays, from the sun stimulate melanocytes to produce pigment.
The human testicle .The two muscles that regulate the temperature of the testes are the dartos andcremaster muscles:â¢ Dartos Muscle The dartos muscle is a layer of smooth muscle fibers in the subcutaneous tissue of thescrotum (surrounding the scrotum).
How does the circulatory system help regulate body temperature? The circulatory system helps regulate body temperature by transporting heat, carried by the blood, and then either constricting or dilating the blood in the tissues to inc â¦ rease or decrease the temperature. If it needs more heat, more blood is supplied by dilation.