Psyc201 Test 1, Week 3 Flashcards
Resting Membrane Potential
The electrical potential across a neuron’s membrane when it is at rest, typically around -70 mV (inside negative).
Depolarization
A change in membrane potential that makes the inside of the cell less negative (more positive).
Hyperpolarization
A change in membrane potential that makes the inside of the cell more negative.
Ion Channels
Proteins in the cell membrane that allow specific ions to pass through.
Sodium (Na+) Distribution
Higher concentration outside the cell.
Potassium (K+) Distribution
Higher concentration inside the cell.
Action Potential Threshold
The membrane potential (-60 mV) at which voltage-gated Na+ channels open.
Na+ Influx
The rapid movement of sodium ions into the cell during depolarization.
K+ Efflux
The movement of potassium ions out of the cell during repolarization.
Na+/K+ Pump
Actively transports 3 Na+ ions out and 2 K+ ions into the cell to restore resting potential.
Action Potential Summary
Depolarization, Na+ influx, repolarization, K+ efflux, resting potential restoration.
Refractory Period
The period after an action potential when another action potential cannot occur.
Absolute Refractory State – Not responsive at all (about 1 ms)
Relative Refractory State – Only responsive to strong stimuli (about 2 -4 ms)
Cocaine’s Effect on Neurons
Blocks voltage-gated Na+ channels, preventing action potentials.
Unmyelinated Neurons
The action potential travels continuously along the axon.
This is (relatively) slow (up to 10 m/s).
Myelinated Neurons
In myelinated neurons, the action potential jumps from one Node of Ranvier to the next. This is much faster (up to 100 m/s).
This is referred to as “Saltatory Conduction”
Synaptic Communication Process
- Neurotransmitters are synthesized in the neuron and stored in vesicles.
- Upon the arrival of an action potential voltage gated Ca2+ channels open.
- This ultimately leads to neurotransmitter vesicles fusing with the cell membrane, releasing the neurotransmitter into the synaptic cleft.
- The neurotransmitter then diffuses in the synapse and will eventually attach itself to specific receptors (proteins) on the postsynaptic cell.
- This interaction induces a change in the postsynaptic potential (EPSP or IPSP).
- The neurotransmitter only binds shortly to the receptor.
- Once it is released it can diffuse away, be metabolized (broken down) or taken back up into the presynaptic terminal (recycling).
Vesicles
Store neurotransmitters in the presynaptic terminal.
Reuptake
Reabsorption of neurotransmitters into the presynaptic terminal.
GABA
Inhibitory neurotransmitter, involved in anxiety regulation.
Glutamate
Excitatory neurotransmitter, involved in learning and memory.
Dopamine
Neurotransmitter involved in reward, motivation, and motor control.
Serotonin
Neurotransmitter involved in mood, sleep, and appetite.
Cotransmission
Release of multiple neurotransmitters from a single neuron.
Ionotropic Receptors
Fast-acting receptors that directly open ion channels.
– Example Glutamate
* Influx of Na+ - ions
* Excitatory – Relevant for learning and memory
– Example GABA
* Gamma amino butyric acid
* Influx of Cl- - ions
* Inhibitory – Relevant for anxiety (reduced GABA)
Diazepam prolongs the opening of the GABA receptor and helps with my anxiety.
Almost all drugs used for mental health problems influence this communication
