BSC 215 Lecture Notes - Lecture 34: Autonomic Nervous System, Proprioception, Special Senses
11 Jun 2018
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Sensory Receptors
One of the characteristics of a living organism is its ability to respond to stimuli. The human
sensory system is highly evolved and processes thousands of incoming messages simultaneously.
This complexity allows you to be aware of your surroundings and take appropriate actions.
Sensory receptors are dendrites of sensory neurons specialized for receiving
specific kinds of stimuli. Sensory receptors are classified by three methods:
• Classification by receptor complexity:
• Free nerve endings are dendrites whose terminal ends have little or no
physical specialization.
• Encapsulated nerve endings are dendrites whose terminal ends are
enclosed in a capsule of connective tissue.
• Sense organs (such as the eyes and ears) consist of sensory neurons
with receptors for the special senses (vision, hearing, smell, taste, and
equilibrium) together with connective, epithelial, or other tissues.
Classification by location:
• Exteroceptors occur at or near the surface of the skin and are sensitive
to stimuli occurring outside or on the surface of the body. These
receptors include those for tactile sensations, such as touch, pain, and
temperature, as well as those for vision, hearing, smell, and taste.
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Document Summary
One of the characteristics of a living organism is its ability to respond to stimuli. The human sensory system is highly evolved and processes thousands of incoming messages simultaneously. This complexity allows you to be aware of your surroundings and take appropriate actions. Sensory receptors are dendrites of sensory neurons specialized for receiving specific kinds of stimuli. Classification by location: exteroceptors occur at or near the surface of the skin and are sensitive to stimuli occurring outside or on the surface of the body. These receptors include those for tactile sensations, such as touch, pain, and temperature, as well as those for vision, hearing, smell, and taste. Interoceptors (visceroceptors) respond to stimuli occurring in the body from visceral organs and blood vessels. These receptors are the sensory neurons associated with the autonomic nervous system: proprioceptors respond to stimuli occurring in skeletal muscles, tendons, ligaments, and joints. These receptors collect information concerning body position and the physical conditions of these locations.
