Sensory Systems Flashcards
Give an example of an organ that has no sensory receptors at all.
the liver
What is meant by sensory modality?
type of stimulus activating a particular receptor
What 2 types of receptors are involved in peripheral sensory processing?
cutaneous mechanoreceptors
proprioceptors
How does transduction occur in sensory receptors?
involves opening or closing of ion channels
What are simple receptors?
free nerve endings
What are complex neural receptors?
nerve endings enclosed in connective tissue capsules
How are Action Potentials generated at sensory receptors?
- sensory endings do not themselves generate action potentials
- local current flows a short distance to where membrane has voltage gated ion channels that generate APs
How is the intensity of a stimulus conveyed?
through frequency of APs being generated and also number of receptors activated
What is meant by adaptation in reference to some mechanoreceptors?
they can adapt to a stimulus and ‘learn’ to only signal a change
Give 2 examples of rapidly/moderately adapting receptors.
Meissener’s Corpuscles and Pascinian Corpuscles
Give an example of slowly adapting receptors.
Merkel’s discs
What receptors do not adapt?
nocireceptors (pain)
Describe a Pascinian Corpuscle.
myelinated nerve ending enclosed by a connective tissue sheath that is layered like an onion with fluid in-between
What is meant by convergence in relation to sensory neurones?
multiple presynaptic neurones provide input to a smaller number of postsynaptic neurones
What is the 2 point discrimination test?
ability to discriminate between 2 adjacent stimuli
What is acuity?
ability to locate a stimulus on the skin and differentiate it from another close by
What is lateral inhibition?
information from afferent neurones at edge of stimulus is strongly inhibited compared with information from stimulus centre
Where does all sensory information go?
to the brain, relayed through thalamus to somatosensory cortex
