Neuronal communication Flashcards
(4 cards)
1
Q
Role of myelin sheath
A
- Acts as an insulating layer which protects the axon
- Speeds up the conduction of the impulse along the axon (100 m/s) as it leads to the impulse jumping over the nodes of Ranvier.
2
Q
Types of sensory receptors
A
- mechanoreceptors (for pressure and movement eg Pacinian corpuscle)
- chemoreceptors (for chemicals eg olfactory receptors)
- thermoreceptors (for temperature changes eg end-bulbs of Krause inside the mouth)
- photoreceptors (for light eg cone cells)
3
Q
What is a transducer?
A
The ability to convert a stimulus into a nervous impulse (generator potential).
4
Q
How the Pacinian corpuscle acts as a transducer
A
- Sensory neurone is in its resting state as the Na+ channels are too narrow to allow Na+ to diffuse (Resting potential).
- Pressure is applied to the PC, which changes its shape, causing the membrane surrounding the neurone to stretch.
- Due to this, the Na+ channels widen and allow Na+ to diffuse into the neurone.
- The influx of positive ions changes the potential of the membrane (it becomes depolarised), which results in a generator potential.
- Generator potential then creates an action potential.