Why do you have arm hair?
Hair covers much of our bodies. But why? Think of the way that you can sense something brush against your arm. Your arm hair is important in providing this type of sensation and making you aware of your environment. Also, hair can trap heat and keep your body warm.
Hair and Nails
Along with the skin, the integumentary system includes the nails and hair. Both the skin and hair contain the tough protein, keratin. The keratin makes your nails and hair tough and strong.
Fingernails and toenails both grow from nail beds. As the nail grows, more cells are added at the nail bed. Older cells get pushed away from the nail bed and the nail grows longer. There are no nerve endings in the nail. Otherwise cutting your nails would hurt a lot!
Nails act as protective plates over the fingertips and toes. Fingernails also help in sensing the environment. The area under your nail has many nerve endings. These nerve endings allow you to receive more information about objects you touch.
Hair sticks out from the epidermis, but it grows from the dermis (Figure below). Hair grows from inside the hair follicle. New cells grow in the bottom part of the hair, called the bulb. Older cells get pushed up, and the hair grows longer. The cells that make up the hair strand are dead and filled with keratin.
Hair, hair follicle, and oil glands. The oil, called sebum, helps to prevent water loss from the skin.
Hair, especially on the head, helps to keep the body warm. The air traps a layer of warm air near the skin and acts like a warm blanket. Hair can also act as a filter. Nose hair helps to trap particles in the air that may otherwise travel to the lungs. Eyelashes shield eyes from dust and sunlight. Eyebrows stop salty sweat and rain from flowing into the eye.
hair follicle: Cavity containing the root of a hair.
keratin: Tough protein in nails and hair.
- Hair and nails are made of keratin, a tough protein.
- Nails act as protective plates over the fingertips and toes.
- Hair serves many functions such as acting as a filter and keeping the body warm.
Use the resources below to answer the questions that follow.
- What is the function of your nails? How do they grow?
- What is the function of the oil glands in your skin?
- What are the functions of hair? How does the importance of these functions vary between organisms?
- What is the function of the integumentary system in the interior of your body?
- If the integumentary system did not extend to the interior of the body, what problems could this cause for infection?
- What is an appendage?
- Why do people call the skin the largest sense organ in the body? What kinds of things does it sense?
- What do we need to produce vitamin D? Where is it produced?
- What are two functions of your nails?
- What are two functions of your hair?