Midterm 1 - Neurotransmission Flashcards
Membrane Potential
Electrical charge across a membrane. The difference between the inside and the outside.
Resting Potential
The membrane potential when the axon is neither being excited nor inhibited.
- 70 mV
Depolarization
- Towards 0
- A rise in the membrane potential from the normal resting potential.
- EPSP
Hyperpolarization
- In the negative direction
- A decrease in the membrane potential relative to the resting potential.
- IPSP
Action Potential
A brief electrical impulse that’s responsible for the conduction of information down an axon.
AKA, “spike,” “the neuron fires”
Critical Firing Level
- The threshold of excitation.
- The value of the membrane potential that must be reached in order to produce an action potential.
- Change = +15 mV (-55 mV)
Where Do EPSPs and IPSPs Occur?
Dendrite
How long is an AP?
1 mSec
Summation
When 2 EPSPs build on each other.
2 Types.
2 Types of Summation
- Temporal - Same neuron sends a signal 2x in a row in a very short time period.
- Spatial - When 2 different neurons send a NT to a neuron at about the same time.
Does Summation Apply to IPSPs?
NO.
2 IPSPs building on each other don’t yield a reverse spike - the most that happens is that the membrane potential just drops to a certain level and stays there.
Concentrations of Ions In and Out of Cell At Rest
- More sodium (Na+) outside than inside
- More potassium (K+) inside than outside
- More chloride (Cl-) outside than inside
- More calcium (Ca2+) outside than inside
Resting Membrane Potential
(Visual)
Action Potential Graph
Driving Forces on an Ion
(2)
- Diffusional Force - An ion will want to go from an area of high concentration to an area of low concentration.
- Electrostatic Force - Opposites attract.