The Sense of Touch

Learning objectives

To observe the distribution on the human body of two types of skin, hairy and hairless.
To discover the anatomy of the skin in cross section and to understand that hairless skin has many more touch receptors than hairy skin.
To observe the variety and locations of the sensory receptors in the three layers of skin (epidermis, dermis and hypodermis)
To understand that tactile perception involves different types of stimuli: heavy or light pressure, brushing, stretching.
To observe the perception of different stimuli applied to the surface of the skin and the propagation of nerve impulses from the sensory receptors of the skin toward the brain, by way of nerve fibers.
To understand that different types of receptors are specific in their sensitivity and so only react to certain types of stimuli.

The skin is the largest of all organs. It is also the organ of the fifth sense: touch.

This animation presents illustrations in cross section of two types of skin:

Hairless skin (glabrous skin): this contains a large panel of different sensory receptors and has a thick epidermis. Examples would be the palms of the hands or the soles of the feet.
Hairy skin: this contains different receptors and has a thinner epidermis. This is the case for the majority of the skin on the body surface.

In this animation, different stimuli can be applied to each type of skin. (Light pressure, Heavy pressure, Light brushing, Stretching). The sensory receptors brought into play, as well as the nerve impulses produced can be visualized.