L108: Senses and Perception Flashcards
What type of nerve purveys stimuli information from a skin receptor to the CNS?
Primary, afferent fibre OR
Pseudo, unipolar cell
What defines neurones’ receptive fields?
The distribution of ‘clusters’ of peripheral nerve branches, each with a nerve ending (receptor). These also overlap.
How does the size of receptive fields differ in different parts of the body?
- Lots of small receptive fields and the periphery (fingertips, toes) with a lot of overlap between fields;
- This reduces towards the trunk where there are large receptive fields with less overlap.
What does a small ‘2-point discrimination’ value i.e., being able to discriminate clearly between 2 points (stimuli) indicate?
- Areas with small receptive fields;
- Large cortical (brain) representation.
E.g. fingertips
What does a large ‘2-point discrimination’ value i.e., being able to discriminate clearly between 2 points (stimuli) indicate?
- Areas with large receptive fields (trunk);
- Small cortical (brain) representation.
E.g. trunk
What activates mechanoreceptors?
Pull on cytoskeletal elements, opens ion-gated channels
What activates chemoreceptors?
Reception via G-protein coupled receptors
prolonged activation of receptors with lingering tastes etc.
What determines the intensity of a stimulus?
AP frequency i.e. greater intensity = greater AP frequency
What is the perineurium?
The sheath of connective tissue surrounding a bundle (fascicle) of nerve fibres within a nerve (inner CT)
What is the epineurium?
The outermost layer of dense, irregular connective tissue surrounding a peripheral nerve, supplies multiple fascicles
Where are the cell bodies of sensory axons found?
Dorsal root ganglia (DRG)
What is mechanoreception?
Touch
What is nociception?
Pain
Where are first order neurones located?
At the periphery
Where are second order neurones located?
CNS
