A sensory receptor is a specialized cell or cell process that monitors conditions in the body or the external environment
A sensory receptor is a specialized cell or cell process that monitors conditions in the body or the external environment.
Stimulation of the receptor directly or indirectly alters the production of action potentials in a sensory neuron.
The sensory information arriving at the CNS is called a sensation.
A perception is a conscious awareness of a sensation.
Sensations of temperature, pain, touch, pressure, vibration, and proprioception (body position)
Receptors throughout the body
Sensations of smell (olfaction), taste (gustation), balance (equilibrium), hearing, and vision
Specialized receptor cells that are structurally more complex than those of the general senses
Receptor specificity — each receptor responds to one type of stimulus
Tonic receptors — always send signals, thus information is based on the frequency of the action potentials
Phasic receptors — send action potentials only if stimulated
Peripheral adaptation — receptors may stop sending AP even if the stimulus is still present
Humans do not have receptors for every possible stimulus.
Our receptors have characteristic ranges of sensitivity.
A stimulus must be interpreted by the CNS. Our perception of a particular stimulus is an interpretation and not always a reality.
Receptors for general senses classified by location:
Exteroceptors provide information about the external environment.
Proprioceptors monitor body position.
Interoceptors monitor conditions inside the body.
Receptors for general senses classified by type of stimulus:
Nociceptors = tissue damage
Mechanoreceptors = physical distortion, contact, or pressure
Chemoreceptors = chemical composition of body fluids
Bipolar olfactory receptors (N I)
Basal cells (stem cells)
Olfactory glands (Bowman’s glands)
Nerves (axons of N I)
Gustatory receptors are clustered in taste buds, which contain gustatory cells that extend taste hairs through a taste pore.
Three types of papillae (epithelial projections) on human tongue:
Also water and umami (characteristic of broth)
Chambers of the eye
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