Sensory Receptors Flashcards
What are mechanoreceptors?
Receptors responsible for sensing mechanical stimuli
What is meant by ‘adequate stimulus’?
This is the type of energy (stimulus) that a receptor normally responds to.
What are proprioceptors?
Mechanoreceptors in joints and muscle that signal information related to body or limb position.
What are nociceptors?
Receptors that detect painful stimuli.
What is a receptor/ generator potential?
A graded membrane potential change caused by adequate stimulus on a receptor.
If it reaches a threshold, it will cause the formation of an action potential.
What is the adequate stimulus for cutaneous mechanoreceptors and proprioceptors?
Membrane deformation
Describe the mechanism for sensory transduction on the skin?
Nerve endings or accessory non-neural structures (e.g. hair follicles) are stimulated, causing a receptor potential to occur. If this receptor potential is large enough to exceed a threshold level, it will stimulate the formation of an action potential.
Describe the process of adaptation of mechanoreceptors?
Initially, stimulus is large enough to cause a generator potential which exceeds threshold and stimulates an action potential.
As stimulus proceeds, this graded generator potential declines rapidly and AP ceases.
Describe the structure of the Pacinian Corpuscle.
Consists of a myelinated neuron with a naked nerve ending, surrounded by a capsule of layered membrane lamella separated by fluid.
How does the Pacinian Corpuscle operate?
Mechanical stimulus deforms the capsule
Stretching of the nerve ending opens sodium ion channels and sodium floods in.
This local depolarisation is the generator/ receptor potential and, if large enough, will cause an action potential to fire along the myelinated neuron.
What is the role of the fluid in the capsule of the Pacinian Corpuscle nerve ending?
This fluid rapidly dissipates the stimulus, allowing the generator potential to decline rapidly and the action potential will stop.
Therefore, the fluid has its role in allowing rapid adaptation of the Pacinian Corpuscle.
Name one advantage and one disadvantage of convergence of primary sensory neurons onto secondary neurons.
Advantage- Allows summation of sub-threshold stimuli to generate a receptor potential which exceeds threshold and creates an action potential
Disadvantage- Gives a large sensory receptive field and so a relatively insensitive area- Hard to distinguish between two points close together.
What do muscle spindles monitor?
Muscle length and rate of change of muscle length
What do Golgi tendon organs monitor?
Tension on tendons
What is the difference between how muscle spindle and golgi tendon organs operate in respect to muscle position?
Muscle spindle operates in parallel with muscle
Golgi tendon organs operate in series with muscle
