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).
The hypothalamus is the temperature-regulating centre of the brain. It contains receptors which are sensitive to the temperature of the blood flowing through the brain. Temperature sensitive receptors in the skin also feed back information to the hypothalamus about the temperature of the skin surface.Changes in core body temperature cause the hypothalamus to send nerve impulses to the sweat glands, muscles and blood vessels to raise or lower the temperature.If the core temperature goes up the body loses heat to bring it down again.hanges in core body temperature cause the hypothalamus to send nerve impulses to the sweat glands, muscles and blood vessels to raise or lower the temperature. If the core temperature goes up the body loses heat to bring it down again.