16.1 Properties and Types of Sensory Receptors

receptor

structure specialized to detect a stimulus; some are bare nerve endings

true sense organs

structure that combines nerve tissue surrounded by other tissues that enhance response to a certain type of stimulus; type of receptor that includes a tissue and receptor

transduction

the conversion of one form of energy to another; Fundamental purpose of any sensory receptor; Convert stimulus energy (light, heat, touch, sound, etc.) into nerve signals; two stages

sensation

first stage of transduction; sensory receptor detects stimulus, creates small local electrical change (the receptor potential)

perception

conscious experience and interpretation of a stimulus; Not all sensations lead to this—many signals are filtered out before reaching cortex

modality

type of stimulus or the perception it produces (vision, hearing, taste); Determined by which region of the brain is “wired” to receive the information

location

where a stimulus is located; Encoded by which nerve fibers are firing

receptive field

area within which a sensory neuron detects stimuli

resolution

ability to distinguish between two close-together stimuli

intensity

strength of stimulus; encoded by which tybe of fibers respond, how many fibers respond, and how fast the fibers are firing

duration

how long a stimulus lasts; encoded by changes in firing frequency overtime

sensory adaption

if a stimulus is prolonged, firing of the neuron gets slower over time and we become less aware of it

phasic receptors

adapt quickly; burst of signals when stimulus starts, then reduce/stop signaling even if stimulus continues

tonic receptors

adapt slowly; action potentials continue more steadily while stimulus is present

general (somatosensory and somesthetic) senses

widely distributed in skin, muscles, tendons, joints, viscera

special senses

limited to head, innervated by cranial nerves, and involve complex sense organs