The contraction of the piloerector muscles (pilomotor muscle or arrector pili) in humans causes
The Correct Answer and Explanation is:
The contraction of the piloerector muscles (also known as arrector pili muscles) in humans causes the hair follicles to become erect, which is commonly referred to as “goosebumps.” This reaction is part of the body’s response to certain stimuli, such as cold temperatures or strong emotional experiences (e.g., fear or excitement).
Explanation:
The piloerector muscles are tiny muscles located at the base of each hair follicle. These muscles are smooth muscles, meaning they are involuntary and operate without conscious control. When these muscles contract, they pull on the hair follicle, causing the hair to stand upright. This phenomenon, known as piloerection, results in the appearance of goosebumps on the skin.
Piloerection is believed to be a vestigial reflex, meaning it is a leftover trait from our evolutionary ancestors. In animals, this response is used to make them appear larger or more intimidating when threatened. For example, when a cat feels threatened, its fur stands on end, making it appear bigger and more formidable to predators or rivals. In humans, while the effect is less noticeable due to the relative lack of body hair compared to other animals, it still occurs as a survival mechanism to signal emotional or physical responses to certain situations.
In cold environments, piloerection serves a function related to thermoregulation. When the hair stands up, it traps a layer of air between the hair and the skin, which can provide additional insulation, helping to retain body heat. However, since humans have much less body hair compared to other mammals, the insulating effect is minimal today, making the reflex largely unnecessary from a practical standpoint.
Overall, the contraction of the arrector pili muscles is a physiological response tied to our fight-or-flight mechanisms and thermoregulation.
