sense of touch or mechanoreception is one that allows organisms to perceive qualities of objects and media such as pressure, temperature, roughness or smoothness, hardness, etc. In the human being is considered one of the five senses básicos.El sense of touch is found mainly in the skin, body found in different types of nerve receptors that are responsible for transforming the various types of external stimuli sensitive information be interpreted by the brain.
Types
* Micron. They are formed by the termination of an axon in a spiral inside a joint capsule ovoid, are in sensitive areas like lips, fingertips, nipples, palm of hand, especially in areas where there is hair. Are associated with the ability to read Braille or enjoy a kiss, for recognizing the body part touched and to identify the texture of objects that act as stimuli. These receptors were discovered by a German physician named Georg Meissner who owe their name.
* Cells or disks Merkel cells are capable of acting as receptors sensitive to pressure. Are concentrated predominantly on the palms and soles of the feet. Merkel cells are located in the germinative layer and are associated with epithelial cells by desmosomes and their cytoplasm is characterized by the abundance of cytokeratin intermediate filaments.
basal face, outer, Merkel cell is associated with nerve terminal that adopts a disk shape which corresponds to the terminal of a fiber afferent axon fibers belonging to a sensory neuron, which is attached to it.
The cytoplasm of Merkel cells can synthesize and accumulate membrane vesicles containing a dense material that stores chromogranins associated with small molecules. When Merkel cell is deformed by compression of the epidermis, they tend to release their vesicles, vesicles with a substance capable of acting as a neurotransmitter and can induce the depolarization of nerve terminal associated with it, which will eventually generate the discharge of action potentials in the axon of the sensory neuron. Its characteristics are considered to belong to the Merkel cell neuroendocrine system diffuse. * Pacinian corpuscles: tactile corpuscles are located in the deep to the hypodermis. They are oval, approximately half a millimeter in length and consist of a thick capsule of concentric layers inside which is the nerve ending. They are located in the deep zone of the skin, especially in the fingers and toes, but are not abundant. Are treated dendrites (neuronal extensions) encapsulated in bald (glia cells) surrounded by fibrous connective tissue that detect pressure and deformation of the skin. The stimulation of Pacinian corpuscles are short-lived. Are those that respond the degree of pressure and vibration that we feel, we can realize the consistency and weight of objects and whether they are hard or soft. In some cases, the weight is measured according to the strain that causes us to lift an object. Therefore it is said that the burden is felt by the "muscular sense." They were discovered by Abraham Vater in 1741, who dubbed them Nervæ Papilæ., But fell into oblivion until 1831, when it Filipo Pacini, focus their research on these nerve receptors.
* Ruffini corpuscles, are nerve endings, heat receptors, sensitive to long and are distributed in the dermis and the subcutaneous region, consisting of fine fibers of collagen (skin protein) ending in a kind of button.
* Krause's corpuscles, are responsible for registering the sensation of cold, which occurs when we come into contact with a body or a space that is cooler than our body. The sensitivity is variable according to the skin region under consideration. Tactile corpuscles are located in the deep to the hypodermis-like Paccini, but smaller (measuring 50 microns) and simplified, as dendrites branched and encapsulated in a shaped cavity bulb. They are spread throughout the body and in the submucosal tissue of the mouth, nose, eyes, genitals, etc.
Free Nerve Endings *: receivers are simpler and are responsible for transmitting the impulse to the brain. It is considered that there are about four million points of pain spread through the human body, are spread over most of the body surface, as they are branched dendrites between epithelial cells, specialized in pain reception. There are no specific corpuscles act as pain receptors but the painful sensation is captured by free endings and whose ramifications extend the deep layer of the epidermis (Malphigia layer) having places on the skin where it reached concentrations of 200 units per square centimeter.
* pili muscle: Each of the hairs on our body has a muscle called pili that are inserted into it and when it contracts, moves to hair straightening, which puts us "goose bumps."
mechanoreceptors These impulses are conducted to the cord and brain through via the ventral spinothalamic. The information leading integrated to result in spinal motor responses somatic and autonomic in the form of reflections.
