receptor
1. A cell or group of cells specialized to detect a particular stimulus and to initiate the transmission of impulses via the sensory nerves. The eyes, ears, nose, skin, and other sense organs all contain specific receptors responding to external stimuli (see exteroceptor); other receptors are sensitive to changes within the body (see interoceptor). See also baroreceptor; chemoreceptor; electroreceptor; magnetoreceptor; mechanoreceptor; osmoreceptor; proprioceptor.

2. An area of a plasma membrane, consisting of a specially adapted membrane protein, that can bind with a specific hormone, neurotransmitter, drug, or other chemical, thereby initiating a change within the cell. For example, the binding of protein hormones to receptors of target cells initiates the synthesis of a second messenger inside the cell.

receptor (ri-sep-ter) n.
1. a cell or group of cells specialized to detect changes in the environment and trigger impulses in the sensory nervous system. All sensory nerve endings act as receptors. See exteroceptor, interoceptor, proprioceptor.

2. a specialized area of cell membrane that can bind with a specific hormone (e.g. oestrogen r.), neurotransmitter (e.g. adrenergic r.), drug, or other chemical, thereby initiating a change within the cell.

receptor A cell or group of cells that are specialized to respond to particular types of stimulus. There are three main types: chemoreceptors, mechanoreceptors, and radioreceptors. A fourth type, electroreceptors, occurs in some teleosts. When the intensity of the stimulus exceeds a threshold the receptor releases an impulse to the neurones connected to it.

re·cep·tor / riˈseptər/ • n. Physiol. an organ or cell able to respond to light, heat, or other external stimulus and transmit a signal to a sensory nerve. ∎  a region of tissue, or a molecule in a cell membrane, that responds specifically to a particular neurotransmitter, hormone, antigen, or other substance.

receptor A cell or group of cells that are specialized to respond to stimuli of particular types, which may be external (light, sound-waves, odours, etc.) or internal (i.e. changes within the body). When the intensity of the stimulus exceeds a threshold the receptor releases an impulse into the nerve cells connected to it.