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| Your Sense of Touch |
Your Sense of Touch
The skin is your body’s largest organ. The layers of your skin provide a flexible shield against physical injury, infection, and ultraviolet radiation. The skin acts as a container to prevent the loss of vital fluids. It also has insulating properties that help to regulate your body temperature. Your skin is covered with a network of nerve endings that are sensitive to touch, pressure, temperature, and pain.
Your sense of touch is most sensitive on your hands, feet, and face; and less sensitive on your legs, arms, and trunk. Pressure is felt when it causes the skin to deform, but there is no sensation when pressure is applied evenly and there is no deformation.
Scuba divers seldom experience a sense of pressure in depths less than 30 metres because the water pushes evenly on all skin surfaces. Continued touch or pressure tends to be ignored after a few minutes. When our clothes are comfortable, we tend not to notice them wrapped around our bodies shortly after dressing. To detect light touches, hairs on the skin act as tiny levers so that an object weighing just a fraction of a gram can twist a hair in its follicle, cause a local deformation of the skin, and signal a touch sensation.
The skin has a typical temperature of 33 degrees Celsius and is able to detect changes as small as a hundredth of a degree. The skin’s sensitivity to hot or cold varies over the surface of the body and also depends on the body’s recent heat history. On a very hot day, a cloth dipped in warm water can feel delightfully cool. The skin adapts to a reasonable range of temperatures within a few minutes. If you dive into a cold lake, or climb into a hot bath, the thermal sensation soon decreases.
A sensation of pain is generated if the pressure or temperature sensors on the skin are over stimulated. Pain is a warning to the brain that action needs to be taken to avoid harm or damage. In the disease of leprosy, the nerve endings of the extremities are damaged so that pain receptors no longer work. Without pain receptors, those suffering from leprosy receive no warning pain when fingers and toes are damaged.
The result is that the extremities are gradually destroyed, not directly by the disease but by excessive wear that is not moderated by pain. Some types of skin pain, such as burns, tend to persist over time with no adaptation. Other types of skin pain, such as that inflicted by the stab of a needle, tend to decrease rapidly with time.
The skin is your body’s largest organ. The layers of your skin provide a flexible shield against physical injury, infection, and ultraviolet radiation. The skin acts as a container to prevent the loss of vital fluids. It also has insulating properties that help to regulate your body temperature. Your skin is covered with a network of nerve endings that are sensitive to touch, pressure, temperature, and pain.
Your sense of touch is most sensitive on your hands, feet, and face; and less sensitive on your legs, arms, and trunk. Pressure is felt when it causes the skin to deform, but there is no sensation when pressure is applied evenly and there is no deformation.
Scuba divers seldom experience a sense of pressure in depths less than 30 metres because the water pushes evenly on all skin surfaces. Continued touch or pressure tends to be ignored after a few minutes. When our clothes are comfortable, we tend not to notice them wrapped around our bodies shortly after dressing. To detect light touches, hairs on the skin act as tiny levers so that an object weighing just a fraction of a gram can twist a hair in its follicle, cause a local deformation of the skin, and signal a touch sensation.
The skin has a typical temperature of 33 degrees Celsius and is able to detect changes as small as a hundredth of a degree. The skin’s sensitivity to hot or cold varies over the surface of the body and also depends on the body’s recent heat history. On a very hot day, a cloth dipped in warm water can feel delightfully cool. The skin adapts to a reasonable range of temperatures within a few minutes. If you dive into a cold lake, or climb into a hot bath, the thermal sensation soon decreases.
A sensation of pain is generated if the pressure or temperature sensors on the skin are over stimulated. Pain is a warning to the brain that action needs to be taken to avoid harm or damage. In the disease of leprosy, the nerve endings of the extremities are damaged so that pain receptors no longer work. Without pain receptors, those suffering from leprosy receive no warning pain when fingers and toes are damaged.
The result is that the extremities are gradually destroyed, not directly by the disease but by excessive wear that is not moderated by pain. Some types of skin pain, such as burns, tend to persist over time with no adaptation. Other types of skin pain, such as that inflicted by the stab of a needle, tend to decrease rapidly with time.
