7. Resting & action potentials Flashcards
What is voltage? (Action potentials B&B)
The difference in charge between two points
What is current? (Action potentials B&B)
The rate at which charge is flowing
What are the four structures of a neuron? (Action potentials B&B)
- Dendrites
- Soma
- Axon
- Terminal boutons
What is the purpose of the dendrite? (Action potentials B&B)
- Recipient of information from one neuron to the other
- Large receptive field
What is the purpose of the soma? (Action potentials B&B)
Contains machinery that controls processing in the cell and integrates information
What is the purpose of the axon? (Action potentials B&B)
Carries information from the soma to the terminal boutons
What is the purpose of the terminal boutons? (Action potentials B&B)
- Found at the end of the axon
- Communication point to other neurons
What are properties of the neuron important for? (Action potentials B&B)
Within neuron communication
What is the membrane potential? (Action potentials B&B)
- Electrical charge across the membrane
- From an area of higher concentration to an area of lower concentration
What is force of electrostatic pressure? (Action potentials B&B)
The idea that particle with the same forces repel and those with opposite attract
What is the process of the equilibrium potential? (Action potentials B&B)
- P+ ions move across membrane via diffusion
- Increases electric potential across membrane
- Eventually, diffusion force = electrostatic force
What does the resting membrane potential result from? (Action potentials B&B)
The separation of charge across the membrane
What is the process of resting membrane potential? (Action potentials B&B)
- High Na+ outside membrane, high K+ inside the membrane
- At rest, more K+ channels open than Na+
- Na+ into the neuron, K+ out of the neuron
What does the Nernst equation measure? (Action potentials B&B)
The equilibrium potential from any ion
Why are sodium pumps needed? (Action potentials B&B)
Because the membrane is not permeable enough for sodium diffusion
What do sodium pumps do? (Action potentials B&B)
Maintain the ionic concentration gradients (Na+ and K+) across the membrane
Why is ATP broken down? (Action potentials B&B)
To release energy, used to force ions against their concentration gradient
What is an action potential? (Action potentials B&B)
A nerve impulse that allows for communication within the neuron
Where is an action potential generated? (Action potentials B&B)
At the axon hillock
What is hyperpolarisation? (Action potentials B&B)
A change in a cells membrane potential, making it more negative, inhibiting action potentials
What is the order of an action potential firing? (Action potentials B&B)
- Resting potential
- Depolarisation
- Peak action potential
- Repolarisation
- Hyperpolarisation
- Threshold of excitation
What does an increase in the size of stimulation do to an action potential? (Action potentials B&B)
Increases the degree of depolarisation
What do voltage-gated channels do? (Action potentials B&B)
Open when the membrane becomes depolarised
What causes positive membrane potentials and what do they do? (Action potentials B&B)
- Very high degree of depolarisation
- Results in inactivation of Na+ channels
What is the period of time known as, where the majority of sodium channels are inactive? (Action potentials B&B)
Refractory period
What is the process of an action potential? (Action potentials B&B)
1) At rest, most channels are closed
2) Small depolarisation opens some Na+ channels
3) Na+ begins to diffuse in = further depolarisation
4) More Na+ channels open
5) More Na+ moves in
6) Few K+ channels open
7) Some K+ moves in
8) Na+ channels become deactivated (refractory period)
9) Remaining K+ channels open
10) K+ moves in
11) Membrane potential decreases (repolarisation)
12) K+ channels begin to close
13) Membrane potential drops below resting potential (hyperpolarisation)
14) Na+/K+ channels attempt to restore resting membrane potential
