Sensory Nerves Flashcards
What is sensory modality?
The type of stimulus a receptor normally responds to
What are mechanoreceptors?
Sensory receptors stimulated by mechanical stimuli - touch stretch, pressure, deformation.
Detect many stimuli, balance hearing
What are proprioceptors?
Mechanoreceptors in joints and muscles that signal info related to body or limb position.
What are nociceptors?
Respond to painful stimuli
What is a graded membrane potential change called in a sensory nerve?
Receptor or generator potential
Transduction always results in opening/closing of ion channels
Where are action potentials produced from the receptor potential?
Wherever the membrane has voltage gated ion channels
When do you get a higher frequency of action potentials?
larger stimulus causes larger receptor potential
Can activate more receptors
What is meant by adaptation of a mechanoreceptor?
When mechanoreceptor adapts to maintained stimulus and only signals for a change or novel event
Give an example of a sensory receptor that does not adapt?
Nociceptor, important to detect painful stimuli
What is a pacinian corpsucle responsive to?
Vibration and pressure
Describe the structure of a pacinian corpuscle
Myelinated nerve
Naked nerve ending, enclosed in CT capsule
Capsule contains layered membrane lamellae separated by fluid
How are action potentials generated from a pacinian corpsucle
Mechanical stimuli deforms capsule and nerve ending, causing ion channels to open, - generator potential then action potential.
How is the pacinian corpsucle capable of rapid adaptation?
Fluid redistribution of corpsucle rapidly dissipates stimulus, nerve ending no longer stretched
What happens to the pacinian corpsucle when the stimulus is withdrawn?
Capsule springs back - AP fired again
What type of structure is the pacinian corpuscle?
Non-neural accessory structure
