Problem 3 Flashcards
Postsynaptic Potential
- brief changes in membrane potential of the postsynaptic cell caused by the release of neurotransmitters
Whether cell excites or inhibits is dependent on the neurotransmitter
Excitatory postsynaptic potential (EPSP)
- pushes the postsynaptic cell closer to threshold for AP
- -> Depolarizing
Synaptic delay
- Delay between arrival of Ap at axon terminal + creation of a postsynaptic potential
- Reflects the time needed for neurotransmitters to diffuse into synaptic cleft
Inhibitory postsynaptic potential (IPSP)
- moves postsynaptic cell away from threshold for AP
- -> Hyperpolarizing
- increase of resting membrane potential
Spatial summation
The simultaneous summation of potentials ( E / IPSP ) from different locations ( dif. postsyn. membr. ) across the cell body
Temporal summation
- not absolutely simultaneous
- -> the closer they are in time - the greater the overlap
Role of distance in EPSPs
Simultaneous EPSPs from synapses closer to the axon hillock will produce a larger sum than those farther away
Ligand
- molecule of the perfect/correct shape for a receptor
- -> Schlüssel-Schloss Prinzip
-can activate or block the receptor
Endogenous ligands
Neurotransmitters/Hormones made inside the body
Exogenous ligands
Drugs/Toxins that work as neurotransmitters from outside the body
Agonist
Molecule that acts like a neurotransmitter
--> high efficacy
Antagonist
Molecule that prevents the action of a transmitter
--> low efficacy
Ionotropic receptors
control ion channels directly
–> when bound, ion channels open immediately
Metabotropic receptors
activate G-Proteins, which in turn activate ion channels
–> indirect control of ion channel
G-protein
molecule,
- either directly opens ion channel
- or activates another chemical signal which then opens the ion channel