Neuronal Communication 2 Flashcards
What is intracellular recording ?
Recording electrical activity across a membrane of one single cell (one electrode is inside the cell and one is outside)
What is an extracellular recording ?
Recording electrical activity from a population of cells (both electrodes are outside the cell)
What can be measured by an intracellular recording ?
- Resting membrane potential
- EPSPs and IPSPs
- Action potentials
What does it mean when we say that lipid membranes have capacitance ?
The lipid membrane stores charge
Voltage is produced across the membrane
What is the equation for charge ?
Charge = current x time
What is the equation for voltage ?
Voltage = charge stored / capacitance
What is conduction velocity ?
The speed at which propagation of the action potential occurs.
Measured in metres/second
What factors affect conduction velocity ?
- Myelination of the axon- good insulator, increases speed of AP propagation
- Diameter of the axon- the finer the fibre the slower it conducts
- Temperature- increased temp means faster conduction velocity
How does TTX impact neural transmission ?
It binds to the Extracellular side of sodium channels, blocking sodium entry, which prevents depolarisation.
This means that action potentials are not generated, which can lead to respiratory paralysis.
It is found in pufferfish.
How does Tetraethylammonium (TEA+) impacts neural transmission ?
It blocks potassium channels, preventing potassium leaving the cell, which delays depolarisation.
This prolongs the action potentials
How does Novichok impact neural transmission?
It inhibits acetylcholine esterase, which means that Ach is not broken down.
This results in prolonged muscle contraction, causing spasms and death if untreated.
It is an organophosphate
What are compound action potentials ?
Action potentials recorded from a group of neurons
What do demyelinating conditions do ?
Decrease conduction velocity in affected axons.
Can eventually result in block of conduction.
Describe a central neuropathy
Multiple sclerosis
Caused by an autoimmune attack against CNS myelin sheaths
Symptoms: numbness, muscle weakness and motility problems
Describe a peripheral neuropathy
Guillain Barre syndrome
Autoimmune attack on PNS myelin
Often caused by infection eg. Campylobacter
Symptoms: pins and needles, limb weakness
Describe action potentials in myelinated cells
They have saltatory conduction- jumps between nodes to speed up conduction
Fast speed of conduction
