Sensory Receptors 1-2 Flashcards
Define sensory receptors
They are nerve endings with specialized non-neural structures. They convert different forms of energy into action potentials
Name three types of sensory receptors and their function
1: Mechanoreceptors - React to mechanical stimuli i.e pressure, stretch etc…
2: Proprioceptors - Orientate the limbs and the rest of the body (found in muscles and joints)
3: Nociceptors - Pain receptors
An adequate stimulus on one of these receptors causes what ?
A graded potential (Receptor potential/Generator potential)
Activates stretch sensitive ion channels causing ion flow across the membrane.
The larger the stimulus the larger the ____ and the higher the ____of ____.
What is this known as ?
Receptor potential
Frequency of APs
Frequency coding
What is adaption ?
When mechanoreceptors adapt to a maintained stimulus and only signal change
What shows rapid adaption ?
Mechanoreceptors
What receptor does not show adaption ?
Nociceptors
What are the 2 rapid adapting receptors ?
Pancinian corpuscle
Meissner’s corpuscle
What are the 2 slow adapting receptors ?
include Merkel’s discs and Ruffini endings
What is a pancinian corpuscle ?
a myelinated nerve with a naked nerve ending, enclosed by a connective tissue capsule of layered membrane lamellae separated by fluid (like an onion)
If the capsule was removed from the pancinian corpuscle what would happen to the adaption properties ?
bare nerve ending loses much of adaptation
continues to produce a receptor/generator potential
Our ability to tell 2 points on the skin apart depends on two things, what are they ?
1: Neuronal convergence
2: Large receptive field
Define neuronal convergence
Simultaneous sub-threshold stimuli to sum at the secondary neuron, forming a large secondary receptive field and initiating APs.
What indicates a sensitive area ?
Convergence and a large secondary receptive field
Define acuity
The ability to locate a stimulus on the skin and differentiate it from another close by
