Arrector pili facts for kids
The arrector pili muscles are tiny muscles found in mammals, like humans. They are attached to your hair follicles, which are the small pockets in your skin where hairs grow. When these muscles contract, they pull on the hair follicles. This makes your hairs stand on end, which you might know as "goose bumps" or "chicken skin."
How Arrector Pili Muscles Work
Each arrector pili muscle is made of special fibers called smooth muscle. These fibers connect to several hair follicles at the same time. These muscles are controlled by your body's autonomic nervous system. This means you cannot choose to make them contract. Their movement is completely involuntary.
Things like feeling cold or scared can make your nervous system send signals to these muscles. When they get these signals, they contract. This causes your hairs to stand straight up.
What Do These Muscles Do?
The contraction of arrector pili muscles serves several important purposes:
- Keeping Warm: For many mammals, the main job of these muscles is to help them stay warm. When hairs stand up, they trap a layer of air close to the skin. This trapped air acts like an insulator, helping the animal keep its body heat.
- Scaring Predators: In some animals, like a porcupine, their long, thick hairs (quills) stand up when the muscles contract. This makes the animal look much bigger and more threatening. It can help scare away predators.
- Helping Skin Oils: The muscles can also put pressure on sebaceous glands. These glands produce an oily substance called sebum. When the muscles contract, they can help push this sebum along the hair follicle to the skin's surface. Sebum helps protect and moisturize your hair and skin.
Images for kids
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Insertion of sebaceous glands into hair shaft
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Cross-section of all skin layers
See also
In Spanish: Músculo erector del pelo para niños
