Slides Flashcards
At it’s peak the action potential approaches what?
The equilibrium potential for Na+
Action potentials are produced by the sudden movement of what into the cell?
Sodium ions
What is the equilibrium potential for Na+?
About +40 mV
What happens when Na+ equilibrium potential is reached?
Voltage gated K+ channels open to allow K+ to leave the cell and restore resting potential.
What was the first transmitter discovered?
Acetylcholine
How was AcH used in the Otto Loewi experiment?
Collected stimulus fluid that slows the heart and found it was transferable
The sequence of synaptic transmission:
- Action potential @ presynaptic axon terminal
- voltage gated calcium channels allow Ca+ into terminal
- Ca+ ions fuse with terminal and burst transmitter
- Transmitter bind to receptors causing an EPSP or IPSP
- PSP’s spread toward axon hillock where an action potential may occur
- synaptic transmission is rapidly stopped
What effects can drugs have in the presynaptic neuron?
Transmitter synthesis, transmitter release, and transmitter clearance
Effect on transmitter synthesis
Drugs block synthesis enzymes, Axonal transport, or the ability to store the transmitter
Effects on transmitter release
Block action potentials by blocking ion channels
Effects on transmitter clearance
Reuptake inhibitors, others allow the transmitter to accumulate by blocking enzymes
Physical dependence
Withdrawal symptoms at drugs absence, tolerance to effects
Psychological dependence
Situation where drug use seems to take over an organisms behavior and dominate motivations
Positive incentive model
Rely on positive reinforcement-drugs produce pleasure and disinhibits behavior
Physical dependence or withdrawal model
Rely on negative reinforcement- avoidance of unpleasant withdrawal symptoms
