Microscopy Image Gallery


Exploration of the Month

April 1998


hair on felt background

Hair



Did you ever wonder why dads always complain about losing their hair? They should! Hair is a very important component of our bodies. Besides contributing to our appearance, hair protects our head from the sun and helps us to "feel" things when we come in contact with them. Hair exists in some very unexpected places on our body. For example, our inner ear has hair to help with our sense of balance. Tiny hairs in our nose prevent dust and other particles from entering our lungs. To the left is some hair photographed on a piece of green felt, which was forcibly removed from somebody's head. OUCH!




Hair comes in a variety of sizes, colors, and shapes. There is a large difference between the hairs on top of your head and the hairs within your inner ear. The below pictures show the differences between straight and curly hairs, for the shape of the cross-sectional area determines the type of hair. The left and middle pictures represent the "round" features of straight hair. The right picture shows the "oval" shape of a curly hair. See the white bars on the pictures? They indicate a distance of fifty micrometers, one-twentieth of a millimeter in the scanned image.


straight hair 500X cross section; straight hair cross section; curly hair

On your head, the average total number of hairs is between 100,000 and 150,000. If you notice some strands on your hairbrush, don't worry! We lose between 50 to 100 hairs a day. Luckily, new hair forms to take the place of ones that have fallen out.


Perhaps the most important function of hair is helping the body perceive our environment. Look down at your arm. Do you see how the hair on your arm enters your skin, or epidermis? Beneath our skin, the hair is rooted in an area called the follicle. Follicles are surrounded by many sensory nerves. These nerves send messages as our conditions change. For example: when the wind blows, the nerves detect the movement of our hair and relay that information to the brain. Even more extreme, when our hair gets pulled by someone else, it really hurts! The painful sensation we feel is the nerves' reaction to being moved. These next images represent the shape of our hair close to the follicle, underneath the skin. Notice the "bulb" characteristics at the base. Why do you think the hair is shaped this way?


portion of hair root portion of hair root 100X portion of hair root 500X




New hair is produced at the follicle where tiny blood vessels provide nourishmnet to the hair cells. As these cells grow and duplicate, they push outward until they exit the skin. Human hair grows at a rate of 1/2 inch per month. This is a picture of Diane Witt, she once held the record for the world's longest hair. The current World Record holder is Mata Jagdamba, of India, whose hair measures 13 feet, 10 inches. Unfortunately, no pictures were available but, could you compute how long it would take to grow hair that long? More fun hair facts can be found at the National Wildlife Federation's web page.



As the hair is produced, it hardens and turns a specific color, in a process called pigmentation. But what makes your hair different in color from others? Well, hair is made from a protein called keratin. It contains the pigment which gives our hair color. In the scanning electron microscope images below, we can see the layers of keratin which compose the skin's makeup. Notice how rough a single stand of hair looks! The layers of keratin look like shingles on a roof. Can you think of any other substances in nature that have this appearance?


layers of keratin 1000X layers of keratin 1000X layers of keratin 1000X


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Last Updated: 6/23/98