SKIN receptors Flashcards
What are the 4 types of sensory receptors in the skin?
- thermoreceptors
- proprioreceptors
- mechanoreceptors (touch)
- nocireceptors
What are the 5 types of mechanoreceptors?
- Pacinian corpuscles
- Meissner’s corpuscles
- Merkel’s discs
- free nerve endings
- Ruffini corpuscle
Where are free nerve endings located?
they are located in both hairy and non-hairy skin
Where are Merkel discs located and what are they sensitive to?
they are located in the deepest layer of the epidermis and are sensitive to touch (texture, shape and edges)
Where are Meissner corpuscles located and what are they sensitive to?
They are located in the folds of non-hairy skin and are sensitive to light pressure and low frequency vibration for discriminative touch
Where are Pacinian corpuscles located and what are they sensitive to?
They are located deep in the dermis and the hypodermis and are stimulated by deep pressure and vibration
Where are Ruffini corpuscles located and what are they sensitive to?
These are located deep in the dermis and subcutaneous tissue and are continuous with the surrounding dermis and they detect sustained deep pressure or distortion of the skin
Describe the adaptation of the Pacinian corpuscle
Due to a __________ stimulus, mechanoreceptive channels in the layers wrapped around the corpuscle are pulled ________. This causes an influx of _______ and ________ ions which causes a _________ potential. As this potential reaches the first node, if we were able to record at the first node, you would see a _________ potential that has a smaller _________ over time (it would be smaller at the second node). If the receptor potential reaches threshold at the first node, an _________ potential will be generated. However, the action potentials fall away in _________ as the amount of _________ decreases and the membrane may be slightly _________ because there are some ______ channels open. This is a form of adaptation - there has been a _______ input and the axon has adapted to that (based on the availability of _______ channels which are not all being made ready after each ____________). There is also a mechanism built into the layers to allow the neuron to rapidly adapt - the layers allow a ________ relaxation so if you disturb the ________ ending, there is a big burst of _______ potentials but then there is some ________ of the membrane which allows the membrane underneath to _______ again and for the ion channels to _______.
Due to a mechanical stimulus, mechanoreceptive channels in the layers wrapped around the corpuscle are pulled open. This causes an influx of Na+ and Ca2+ ions which causes a receptor potential. As this potential reaches the first node, if we were able to record at the first node, you would see a graded potential that has a smaller amplitude over time (it would be smaller at the second node). If the receptor potential reaches threshold at the first node, an action potential will be generated. However, the action potentials fall away in frequency as the amount of depolarisation decreases and the membrane may be slightly refractory because there are some K+ channels open. This is a form of adaptation - there has been a depolarising input and the axon has adapted to that (based on the availability of Na+ channels which are not all being made ready after each hyperpolarisation). There is also a mechanism built into the layers to allow the neuron to rapidly adapt - the layers allow a damp relaxation so if you disturb the sensory ending, there is a big burst of action potentials but then there is some shifting of the membrane which allows the membrane underneath to relax again and for the ion channels to close.
