Neurophysiology Flashcards
how does a neuron transmit information from one part to another?
electricity within in the individual cell (dendrite, cell body, axon)
chemicals from one cell to another in the synapse
changing their charge
What are the key elements in electrical communication of neurons?
Na+, Cl-, K+, Ca2+ ions
What is responsible for charge separation in the neuron and what is its function?
neuronal membrane
separates the inside of the neuron from the outside environment
The extracellular space and the intracellular fluid contain different ion solutions
why is the separation of Na and K important?
Electrical signaling in neurons is primarily due to sodium and potassium separation
Sodium is restricted to the OUTSIDE of the neuron
Potassium is concentrated INSIDE of the neuron
What creates charge separation?
ion pumps in the neuronal membrane
what does a voltmeter do?
It compares the relative, local charge difference between compartments (if the outside is +4 and the inside is +1, the difference is -3 even though both concentrations are still positive)
what is the resting level of the inside of a neuron?
-80mV is standard but different charges have different activation levels
Cells communicate by briefly changing their charge (spike) and this period is called…?
Action potential
For this brief period of time the inside of the cell has more positive charge than the outside
all or none: it either happens or it doesn’t– the size and shape of the action potential is always the same
How does an action potential work?
An action potential is due to the movement of sodium IN and potassium OUT of the neuron
- sodium moves into the cell and makes the neuron + (spike up)
- potassium leaves the cell and makes the cell go down to regular resting level (spike down)
what is the neural code?
the timing and number of action potentials (on a graph, looks like a heart beat thing)
why is the myelin sheath important to transmitting the action potential down the axon?
myelin (from glial cells) is white (white matter!!) and insulates the axon and makes communication much more efficient
transporting a message by standing in a line shoulder to shoulder and raising your hand all the way OR having someone spaces a long way away and they can see your hand raise instead of waiting for the message to go all the way through a bunch of people
what are nodes of ranvier?
spaces (jumps) in between the myelinated axons where chemicals are needed to send the message and not electricity
how do sodium and potassium move in and out of a cell?
opening and closing of channels in the neuronal membrane (do not use energy because of the concentration gradient, the ions want to become more spread out and less concentrated)
how does the neuronal membrane maintain/restore charge separation?
ion pumps that are constantly active (even in “resting” -80Vm) and use energy
Where do action potentials take place and why there?
In the nodes of ranvier because that is where there isn’t a myelin sheath to carry the signal, so it needs to go again
