What is the function of the erector pili muscle?

The erector pili muscle serves the specific function of causing hair to stand up when it contracts. This muscle is a small bundle of smooth muscle fibers that is attached to the base of hair follicles. When stimulated, such as in response to cold temperatures or emotional stimuli like fear, the erector pili muscle contracts, which results in the hair pulling upright. This phenomenon is often referred to as "goosebumps."

Understanding this function is essential, as it relates to the body's response to temperature regulation and emotional states, highlighting the physiological role of the erector pili muscle in human anatomy. The other options involve different aspects of skin and hair biology, such as keratin production and the attachment of hair, but do not describe the specific action that the erector pili muscle performs.