Sense Of Touch

Lesson plans senses

While your other four senses (sight, hearing, smell and taste) are located in specific parts of body, your sense of touch is found all over. This is because your sense of touch originates in the bottom layer of your skin called the dermis. The dermis is filled with many tiny nerve endings which give information about the things with which your body comes in contact. They do this by carrying the information to the spinal cord, which sends message to the brain where the feeling is registered.

The nerve endings in your skin can tell you if something is hot or cold. They can also feel if something is hurting you. Your body has about twenty different types of nerve endings that all messages to your brain. However, the most common receptors are heat, cold, pain and pressure touch receptors. Pain receptors are probably the most important for your safety because they can protect you by warning your brain that your body is hurt!

Some areas of the body are most sensitive than others because they have more nerve endings. Have you ever bitten your tongue and wondered why it hurt so much? It is because the sides of your tongue have a lot of nerve endings that are very sensitive to pain. However, your tongue is not as good at sensing hot or cold. That is why it is easy to burn your mouth when you eat something really hot. Your fingertips are also very sensitive. For example, people who are blind use their fingertips to read Braille by feeling the patterns of raised dots in their paper.

The skin is the biggest sensory organ in the human body and very sensitive to touch. The skin consists of two main layers, the epidermis and dermis. The skin has a lot of receptors that are sensitive to stimuli such as warmth, cold, pain, touch and pressure. The receptors are connected to nerves. When a receptor is stimulated, an impulse is produced and sent through the nervous system to the brain to be evaluated.

The sensitivity of the skin is different on different parts of the body. The degree on sensitivity depend on:
(a) The thickness of the epidermis

The thicker the epidermis, the lower the sensitivity is. Example: The epidermis is thickest on the sole of the foot.

(b) The number of receptors.

The larger the number of receptors, the higher the sensitivity is. Example: The ends of the fingers and the neck have large numbers of receptors.

The high sensitivity at the ends of the fingers enables the blind to read Braille by using fingertips.
lesson plans senses