Sensation and sensory receptors Flashcards
How are sensory receptors specialized?
specialized to respond to stimuli.
- activation of a sensory receptor results in graded potentials that trigger nerve impulses along the afferent PNS fibers coursing to the CNS.
What are the 3 ways to classify sensory receptors?
(1) By the type of stimulus they detect
(2) By their body location
(3) By their structural complexity
What are mechanoreceptors?
respond to mechanical force such as touch, pressure (including blood pressure), vibration, stretch, and itch (causing the deformation of the membrane of the sensory ending)
How do thermoreceptors respond?
sensitive to temperature changes
How do photoreceptors respond?
respond to light (such as those of the retina of the eye)
How do chemoreceptors respond?
respond to chemicals in solution (molecules smelled or tasted, or changes in blood or interstitial fluid chemistry)
What are nociceptors?
sensitive to pain-causing stimuli (extreme heat, extreme cold, excessive pressure, and inflammatory chemicals are all interpreted as painful). These signals stimulate subtypes of thermoreceptors, mechanoreceptors, and chemoreceptors
What are exteroceptors?
- Respond to stimuli arising outside the body
- found near body surface
- Include skin and most receptors of the special senses (vision, hearing, equilibrium, smell, and taste)
- Sensitive to touch, pressure, pain, and temperature receptors
What is another name for interoceptors?
- Aso called visceroceptors
What are interoceptors?
- Respond to stimuli arising within the body
- Found in internal viscera and blood vessels
- Sensitive to chemical changes, tissue stretch, and temperature changes
- Sometimes their activity causes us to feel pain, discomfort, hunger, or thirst
What are proprioceptors?
- Found in: skeletal muscles, tendons, joints, ligaments, and connective tissue coverings of bones and muscles
- Respond to degree of stretch of the organs they occupy
- Give information concerning movements and position of the body
- Constantly “advise” the brain of our body movements by monitoring how much the organs containing these receptors are stretched.
What are 2 types proprioceptors? How do they work?
- muscle spindle provides information about changes in muscle length
- The Golgi tendon organ is provides information about changes in muscle tension
What are some examples of complex receptors?
- Photoreceptors and retinal bipolar cell axons
- Hair cells and auditory axons nerve
- Taste cells and taste nerve axons
What are Tactile corpuscles or Meissner’s corpuscles
- Small receptors in which a few spiraling sensory terminals are surrounded by Schwann cells
and then by a thin egg-shaped connective tissue capsule - Mechanoreceptors; light pressure, vibration of low frequency, and are receptors for discriminative touch
What are Lamellar corpuscles or Pacinian corpuscles?
- Scattered deep in the dermis, and in subcutaneous tissue underlying the skin
- Mechanoreceptors; deep pressure and stretch, and vibration of high frequency
- largest corpuscular receptors
What are Bulbous corpuscles or Ruffini endings?
- Lie in the dermis, subcutaneous tissue, and joint capsules, contain a spray of receptor
endings enclosed by a flattened capsule - Mechanoreceptors; deep pressure and stretch
- role in other dense connective tissues where they respond to deep and continuous pressure
What are muscle spindles?
- fusiform (spindle-shaped) proprioceptors found throughout the perimysium that wraps individual fascicles of skeletal muscle.
- Muscle spindles detect muscle stretch and initiate a reflex that resists the stretch.
What are tendon organs?
- proprioceptors located in tendons, close to the junction between the skeletal muscle and the tendon
- When muscle contraction stretches the tendon fibers, the resulting compression of the nerve fibers activates the tendon organs. This initiates a reflex that causes the contracting muscle to relax.
What are joint kinesthetic receptors?
- proprioceptors that monitor stretch in the articular capsules that enclose synovial joints.
- Mechanoreceptors and nociceptors
What are sensory receptors?
Structures specialized to respond to stimuli
What happens when a sensory receptor is activated?
Activation of sensory receptors results in GP that trigger AP impulses along the nerve axon to the CNS
Where does sensation and perception occur?
cerebral cortex
For sensation to occur, a stimulus must excite a receptor and action potentials must reach the CNS. How does this happen?
- The stimulus energy must match the specificity of the receptor.
- The stimulus must be applied within a sensory receptor’s receptive field—the area the receptor monitors.