Mechanoreceptors in the skin, muscles, or the walls of blood vessels are examples of this type. A general sense is one that is distributed throughout the body and has receptor cells within the structures of other organs. Within the realm of physiology, senses can be classified as either general or specific. Other overlooked senses include temperature perception by thermoreceptors and pain perception by nociceptors. Also, what is referred to simply as touch can be further subdivided into pressure, vibration, stretch, and hair-follicle position, on the basis of the type of mechanoreceptors that perceive these touch sensations. The most obvious omission from this list is balance. However, these are not all of the senses. Another physical stimulus that has its own type of receptor is temperature, which is sensed through a thermoreceptor that is either sensitive to temperatures above (heat) or below (cold) normal body temperature.Īsk anyone what the senses are, and they are likely to list the five major senses-taste, smell, touch, hearing, and sight. Physical stimuli, such as pressure and vibration, as well as the sensation of sound and body position (balance), are interpreted through a mechanoreceptor. Additionally, pain is primarily a chemical sense that interprets the presence of chemicals from tissue damage, or similar intense stimuli, through a nociceptor. Osmoreceptors respond to solute concentrations of body fluids. Chemical stimuli can be interpreted by a chemoreceptor that interprets chemical stimuli, such as an object’s taste or smell. Receptor cells can be further categorized on the basis of the type of stimuli they transduce. Some other organisms have receptors that humans lack, such as the heat sensors of snakes, the ultraviolet light sensors of bees, or magnetic receptors in migratory birds. For humans, the only electromagnetic energy that is perceived by our eyes is visible light. ![]() Other stimuli include the electromagnetic radiation from visible light. Some stimuli are physical variations in the environment that affect receptor cell membrane potentials. Some stimuli are ions and macromolecules that affect transmembrane receptor proteins when these chemicals diffuse across the cell membrane. Physical changes in these proteins increase ion flow across the membrane, and can generate an action potential or a graded potential in the sensory neurons.Ī third classification of receptors is by how the receptor transduces stimuli into membrane potential changes. Other transmembrane proteins, which are not accurately called receptors, are sensitive to mechanical or thermal changes. For example, a molecule in food can serve as a ligand for taste receptors. Transmembrane receptors are activated by chemicals called ligands. A transmembrane protein receptor is a protein in the cell membrane that mediates a physiological change in a neuron, most often through the opening of ion channels or changes in the cell signaling processes. A receptor cell is changed directly by a stimulus. Receptors are the cells or structures that detect sensations. ![]() ![]() Perception is dependent on sensation, but not all sensations are perceived. Perception is the central processing of sensory stimuli into a meaningful pattern. Sensation is the activation of sensory receptor cells at the level of the stimulus. The central integration may then lead to a motor response.ĭescribing sensory function with the term sensation or perception is a deliberate distinction. The stimulus causes the sensory cell to produce an action potential that is relayed into the central nervous system (CNS), where it is integrated with other sensory information-or sometimes higher cognitive functions-to become a conscious perception of that stimulus. This occurs when a stimulus changes the cell membrane potential of a sensory neuron. ![]() Stimuli from varying sources, and of different types, are received and changed into the electrochemical signals of the nervous system. Describe the processes of phototransductionĪ major role of sensory receptors is to help us learn about the environment around us, or about the state of our internal environment.List the supporting structures around the eye and describe the structure of the eyeball.Describe the means of mechanoreception for hearing and balance.Distinguish how different tastes are transduced.Describe the structures responsible for the special senses of taste, smell, hearing, balance, and vision.Describe different types of sensory receptors.By the end of this section, you will be able to:
0 Comments
Leave a Reply. |