Action Potentials Flashcards
How many signals can a neuron send at once?
1
A neuron can only transmit at a uniform…
-Strength
-Speed
What can a neuron vary?
The frequency of the signals
What is voltage?
Measure of potential energy generated from separated charges
What is another word for voltage?
Membrane potential
What is another word for membrane potential?
Voltage
What is current?
Flow of charge from one point to another
What is the equation for current?
Current = Voltage/Resistance
What is resistance?
Whatever is getting in the way of the current
Where is a resting neuron more negative?
Inside or Outside
On the inside
Where is a resting neuron more positive?
Inside or Outside
On the outside
What is the resting membrane potential?
-70mV
Polarised
What is the net movement of ions through the sodium-potassium pump?
2K+ in and 3Na+ out
What maintains resting membrane potential?
The sodium-potassium pump
What does the sodium-potassium pump help achieve?
Makes it more positive on the outside
What is another word for the difference in membrane potentials?
Electrochemical gradient
What are voltage-gated channels?
They open and close in response to changes in membrane potential
At what voltage do Na⁺ voltage-gated channels open?
55mV
What are ligand-gated channels?
They open when neurotransmitters latch to their receptors
What is an example of a ligand-gated channel?
Seratonin
What are mechanically-gated channels?
-They open in response to physical stretching of the membrane
-Ions quickly diffuse down concentration gradient
What is the propagation of an action potential?
Action potentials spreading over the surface of an axon membrane
How is an action potential propagated over the surface of the axon?
-As Na⁺ flows into the cell during depolarisation, the voltage of adjacent areas is affected and their voltage-gated Na⁺ channels open
-Self-propagating along membrane
What is another phrase for a travelling action potential?
Nerve impulse
What is another name for a nerve impulse?
Travelling Action Potential
What is continuous conduction?
-Unmyelinated fibres
-Step-by-step depolarisation of each portion of the length of the axolemma
Where does repolarisation occur?
Nodes of Ranvier
Why can repolarisation only occur at nodes of ranvier?
There is a high density of voltage-gated ion channels
What is saltatory conduction?
Current carried by ions flows through extracellular fluid from node to node
Where does saltatory conduction take place?
Myelinated axons
