SENSORY RECEPTION

also called sense perception, means by which an organism detects and responds to changes in its external or internal environment. Organisms have a variety of sensory structures that respond to different stimuli, such as light, pressure, or chemicals, all of which are forms of energy. Once excited, these sensory receptors convert the energy of the stimulus into a behavioral response of the organism. In unicellular organisms environmental signals are received by specialized organelles, such as light-sensitive eyespots or hairlike cilia sensitive to mechanical disturbances. In multicellular organisms sensory signals can be transmitted from a receptor organ to other parts of the body by specialized cells. For example, in all higher animals sensory reception is the special function of sensory neurons, which convert, or transduce, a stimulus into the electrochemical activity of nerve impulses. These impulses are transmitted to the brain, where they are processed and interpreted. In general, the more highly evolved the organism, the more complex is its sensory apparatus. Additional reading E.D. Adrian, The Basis of Sensation: The Action of the Sense Organs (1928), a basic work in the field of sensory physiology; Cold Spring Harbor Symposia on Quantitative Biology, vol. 30, Sensory Receptors (1965), a report of modern concepts and research in the field; John Field (ed.), Handbook of Physiology, section 1, Neurophysiology, vol. 1 (1959), a comprehensive treatise on historical as well as modern concepts of sensory reception. Ainsley Iggo (ed.), Somatosensory System (1973), is another comprehensive handbook. C.A.G. Wiersma