Touch EL: Be able to describe how our skin allows us to feel things and create the sense of touch

Facts about skin! Skin is your largest organ, it makes up about 15% of your body weight and has a surface area on average of 1.86m2 You shed 50 million skin cells every day! That’s about 30,000 – 40,000 skin cells every minute! Luckily your skin is constantly renewing itself.

Touch Skin defines the boundaries between your internal organs and the environment. The sense of touch is actually a combination of three skin senses: Pressure Temperature Pain The stimulus is converted into electrochemical energy transmitted by nerve cells (neurons) and interpreted by the brain into the psychological experience of touch

Touch The specialised receptors for each of the skin senses- pressure, temperature and pain- vary in shape, size, number and distribution E.g. There are many more cold receptors than heat receptors, there are more pain receptors behind the knee than on top of the nose

1. Pressure The stimulus for pressure is physical pressure on the skin. The entire body is sensitive to pressure. Some areas have more receptors so are more sensitive. More sensitive Fingertips Tongue Upper lip Cheek Palm Forehead Foot Less sensitive Belly Upper arm Back Shoulder Thigh Calf

2. Temperature Your skin does not perceive the actual temperature of an object but instead senses the difference in temperature of a new object in comparison to the temperature of an object the skin was already used to (“relative temperature”) E.g. when you enter a pool or lake at first it may seem really cold, because it is colder than the warmer air you were used to, but then you gradually ‘warm up’ after being in the water for awhile (your body adjusts to the temperature)

3. Pain Pain serves as a warning system that signals danger and the risk of injury. Pain can also force people to cope appropriately with an injury. People can have very different pain perception and pain thresholds for both psychological and physical reasons. The perception of pain can depend on a person’s attitudes, previous experiences and culture.

Touch activities Water temperature Comb Skin sensitivity Phantom arm Reflex: eye and knee

Skin sensitivity (pressure) Your subject should not look at the area of skin that is being tested. Do not press too hard! Make sure both tips touch the skin at the same time. Ask your subject if he or she felt one or two pressure points. Record the result. Questions and Comparisons: Try different parts of the body: the arm, leg, fingers, back, neck, head, hand, toes. What part of the body is most sensitive? In other words, where on the body can 2 points be detected with the smallest tip separation? The receptors in our skin are NOT distributed in a uniform way around our bodies. Some places, such as our fingers and lips, have more touch receptors than other parts of our body, such as our backs. That's one reason why we are more sensitive to touch on our fingers and face than on our backs. These data show the minimal distance that 2 points needed to be apart for them to be both felt separately. (published in The Skin Senses, edited by D. R. Kenshalo, Springfield, IL, 1968). How did your measurements compare?