Sense of touch

Topics: Sensory system, Pain, Nervous system Pages: 9 (2849 words) Published: October 28, 2013

Sense of Touch/Feeling

The Skin Senses
Consider the skin has remarkable versatility: It protects us against surface injury, holds in body fluids, and helps regulate body temperature. The skin also contains nerve endings that, when stimulated, produce sensations of touch, pain, warmth and cold. Like several other senses, these skin senses are connected to the somatosensory cortex located in the brain’s parietal lobes.

The Somatosensory Cortex

The skin’s sensitivity to stimulation varies tremendously over the body, depending in part on the number of receptors in each area. ( For example, we are ten times more accurate in sensing stimulation on our fingertips than stimulation on our backs). In general, our sensitivity is greatest where we need it most on our face, tongue, genital areas and hands. The sensory feedback from these parts of the body allows us to do certain tasks such as effective eating, speaking, and grasping. The Sense of Touch, or Feeling

The sense of Touch, or Feeling, is regarded by psychologists as the elementary sense (the first sense) the one sense from which the others have evolved, and of which they are, in a way, an evolution. The sense of Touch, or Feeling, operates by means of certain nerves which have their endings in the outer covering or skin of the body, and also in the internal organism of the body. These nerves report to the mind their contact with outside objects; and, in some cases, certain changes of state or condition in the body itself. By means of this sense we are able to become aware of the size, form, and shape and delight of material objects; of their degree of hardness, roughness, elasticity, etc.; of their temperature; and of other physical characteristics by which we distinguish one material object from another by means of respective reaction to our sense of Touch or Feeling. By means of this sense we also become aware of changes of state or condition in our bodies, such as thirst, hunger, sexual-feeling, and other internal sensations. Sense

Stimulus
Sense Organ
Receptor
Sensation
Skin Senses
External Contact
Skin
Nerve Endings In Skin
Touch, Warmth,
Cold
Pain
Many intense or
extreme stimuli:
temperature,
chemicals,
mechanical
stimuli, etc.
Net of pain
fibers all over
the body
Specialized
pain receptors,
overactive or
abnormal neurons
Acute pain,
chronic pain

The mechanism of the sense of Touch, or Feeling, is composed of many different and varied classes of nerve channels. This being so, the sense of Touch, or Feeling, is really a composite sense, manifesting diverse activities, principal among which are those of pressure, temperature, muscular resistance, pain, contact, etc. This diversity of activity is illustrated of the physiology of the senses: "A lesion which may cut off the possibility of feeling pain in a given part of the body, may leave it still susceptible to sensations of heat and cold; or the sensations of touch may be present while the sensation of pain cannot be aroused. From this we see that nerve impulses, giving rise to sensations of touch, of pain, of temperature, of the muscular sense, must pass upwards to the sensorium by different paths, one of which may be cut off while the others remain. Your somatic sensory system is responsible for your sense of touch. The somatic sensory system has nerve receptors that help you feel when something comes into contact with your skin, such as when a person brushes up against you. These sensory receptors are generally known as touch receptors or pressure receptors

Somatosensory Cortex
Across the body, a network of nerve cells reacts when they experience sensations related to physical perception. Specialized cells react specifically to pain, while others fire in response to passing breezes, pressure, and a wide variety of other sensations, such as the heat of the sun or the chill that comes from an open refrigerator. Impulses travel along these...
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