Neurophysiology Revision Flashcards
What is the resting potential of a neuron?
- 70mV
What is the activation potential of a neuron?
- 55mV
At what potential do Na+ channels become refractory?
+40mV
What causes repolarisation?
Na+ channels becoming refractory and K+ continuing to leave the cell
What causes the absolute refractory peroid?
Inactivation gating - not the same as the resting state of the Na+ channel
What is the purpose of nodes of Ranvier?
Allows for an increase in speed of conduction - where action potentials take place
What are “SNAREs”?
Pairs of molecules on a vesicle which allow it to dock at a target
What does clostridium botulinum target?
The SNARE system (inactivates it)
How are neurotransmitters inactivated?
- Diffusion
- Re-uptake
- Enzymal inactivation
What are the 2 types of receptors neurotransmitters attach to?
- Ionotropic (directly gate ion flow)
- Metabotropic (indirectly gate ion flow or activate other pathways)
How do you measure nerve conduction?
Not the size of action potential rather the sum of all the action potentials in a nerve or the resulting stimulus inside a target such as a skeletal muscle
What do less axons lead to?
Reduced amplitude
What is slowed conduction velocity due to?
Less myelin
What is carpal tunnel syndrome due to?
Median nerve being compressed at the wrist by transverse carpal ligament. Decreases function of axons not myelination
Name an autoimmune channelopathy
- Myasthenia Gravis
- Lambert-Eaton myasthenic syndrome
- Limbic encephalitis
