MICROANATOMY

Detailed explanation-1: -Goosebumps occur when tiny muscles in our skin’s hair follicles, called arrector pili muscles, pull hair upright. For animals with thick fur, this response helps keep them warm.

Detailed explanation-2: -The arrector pili muscle (APM) consists of a small band of smooth muscle that connects the hair follicle to the connective tissue of the basement membrane. The APM mediates thermoregulation by contracting to increase air-trapping, but was thought to be vestigial in humans.

Detailed explanation-3: -Arrector pili muscles are enwrapped by sympathetic pilomotor nerves, which release the neurotransmitter norepinephrine (NE) to trigger muscle contraction and cause hairs to become erect in response to cold.

Detailed explanation-4: -Piloerection is controlled by sympathetic nerves, which innervate arrector pili muscle (APM) that undergo contraction to raise hair follicles during a ‘’fight or flight response” to external stressors such as cold or danger (Fujiwara et al., 2011).