Introduction to Psychology

Introduction to Psychology

© 2015 of 97 3.7 Skin Senses The skin and body senses include the sense of touch, kinesthesis (muscle movement), and equilibrium. The last two are called body senses because they inform us of the body’s position and movement. Touch and Temperature- Touch is important to us in many ways. Sensitivity to extreme temperatures and to pain enables us to escape external danger and alerts us to disorders within our body. Humans are sensitive to at least four tactile sensations: pressure (touch), pain, warmth, and cold. These sensations are conveyed by receptors in the skin and in our internal organs. Mixtures of these four sensations form the basis for all other common skin sensations. The primary receptors for pain and temperature are the free nerve endings, simple nerve cells beneath the skin’s surface that resemble bare tree branches. Basket cell fibers situated at the base of hair follicles are receptors for touch and light pressure. Kinesthesis functions by means of nerve endings in the muscles, tendons, and joints. The sense organs for equilibrium are in the vestibular apparatus of the inner ear. Pain- Pain receptors are found in all body tissues with the exception of the brain, bones, hair, nails, and nonliving parts of the teeth. Free nerve endings in the skin and internal organs respond to intense mechanical, thermal, or chemical stimulation. They then send nerve impulses into the spinal cord, where sensory tracts carry information about pain intensity and location to the thalamus. The thalamus relays the information to the somatosensory and frontal areas of the cerebral cortex. Other tracts from the thalamus direct nerve impulses to the limbic system, which is involved in motivation and emotion. Thus, pain has both a sensory and an emotional component. The Gate Control theory proposes that the experience of pain results from the opening and closing of gating mechanisms in the nervous system. The nervous system has its own built in analgesics of pain impulses from the spinal cord to the brain with opiate-like properties. The natural opiates are called endorphins and exert some sort of pain killing effect by inhibiting the release of neurotransmitters involved in the synaptic transmission. 3.8 Basic Perceptual Phenomena To create our perceptions, the brain carries out two different processing functions. In bottom-up processing, the system takes in individual elements of the stimulus and combines them into a unified perception. In top-down processing, sensory information is interpreted in light of existing knowledge, concepts, ideas, and expectations. The perception of movement is a complex process, sometimes requiring the brain to integrate information from several different sources. Patterns- Recognizing a stimulus implies that we have a perceptual schema - a mental representation or image containing the critical and distinctive features of a person, object, event, or other perceptual phenomenon. Achieve Page 30