CH 12: Synapses Flashcards
Electrical synaptic transmission
Near instantaneous transmission through gap junctions and ion channels
Chemical synapse
Neurotransmitters released and bind to continue signal
Synaptic vesicle
Packaged with Neurotransmitter
Postsynaptic receptor’s
Neurotransmitter receptors
Six categories of neurotransmitters
- Acetylcholine
- Amino acids
- Monoamines
3a.
3b. - Neuropeptides
- Gases
- Purines
Neuro transmitters in the acetylcholine group
ACh
Neurotransmitters in the amino acids group
GABA
Neural transmitters in the monoamine’s group
3a. Serotonin, histamine
3b. Catecholamines:
-Epinephrine
-Norepinephrine
- Dopamine
Neuropeptides are:
Chains of amino acids
Gases that behave like neurotransmitters:
(Can freely pass-through axon terminal) NO, CO
Purines that acts like neural transmitters
Adenosine, ATP
Acetylcholine is stimulatory in _________, but inhibitory in ________
Skeletal muscle tissue
Cardiac tissue
ACh Synaptic transmission; Excitatory pathway
- Action potential reaches axon terminal; opens VG Ca^2+ channel; Ca^2+ move in causing depolarization
- Ca^2+ Triggers exocytosis of ACh
- Vesicles refill so long as Ca^2+ Is an axon terminal
- ACh diffuses across synapse; binds to ligand gated ACh receptors on postsynaptic neurons
- Causes local potential on postsynaptic neuron; Could lead to action potential if threshold reached

Inhibitory pathway: GABA
GABA opens Cl- channels; Cl- enters and Hyperpolarizes the cell (more neg) so harder to stimulate postsynaptic neuron
Excitatory pathway – androgenic
Ex: Norepinephrine
- NE receptor is bound to G protein
- NE binds to NE receptor; breaks off G protein
- G protein activates adenylate cyclase enzyme which activates cAMP
- cAMP is secondary messenger with downstream effects
- One downstream if it can be opening up particularly can get a channels which allows ions to come in and have postsynaptic potential
Signal amplification
One neural transmitter can activate tons of downstream messengers with lots of downstream effects
End of ACh transmission signal
- Degrading of neurotransmitter AChE breaks down ACh
- Reuptake of a neurotransmitter into presynaptic neuron
- Diffusion (Broken up pieces diffuse back into presynaptic neuron across plasma membrane)
Neuromodulators
Longer-term affect over multiple neurons whereas neurotransmitter is short term effect across one synapse
Postsynaptic potentials
Activation or inhibition of postsynaptic neurons as transmit across Synaptic cleft
EPSP
Excitatory postsynaptic potential; any neurotransmitter that helps excite or depolarize postsynaptic neuron
Ex: ACh in skeletal muscle
IPSP
Inhibitory postsynaptic potential; neural transmitter that prevents stimulation of postsynaptic neuron: hyperpolarization
Ex: GABA
ACh in cardiac tissue
Net summation
Combination of IPSPs and EPSPs = Depolarized or hyperpolarized
Temporal summation
Effects from one presynaptic neuron over time ( can reach threshold)
Spatial summation
Effect from multiple neurons at the same time ( can reach threshold)
Presynaptic facilitation
One neuron indirectly enhances the effects of another by Further enhancing presynaptic neurons ability to fire postsynaptic neuron
Presynaptic inhibition
One neuron inhibits firing of another; increases amount of IPSPs so no neurotransmitter is released from second neuron
