2. Chemical Synaptic Transmission Flashcards
What is the first step in synaptic transmission?
The action potential reaches the presynaptic axon terminal.
What happens when the action potential reaches the presynaptic terminal?
Voltage-gated calcium (Ca²⁺) channels open, allowing Ca²⁺ to enter.
What triggers synaptic vesicles to release neurotransmitters?
The influx of Ca²⁺ into the presynaptic terminal.
What occurs after neurotransmitters are released into the synaptic cleft?
Neurotransmitters bind to receptor proteins on the postsynaptic membrane.
What happens when neurotransmitters bind to postsynaptic receptors?
Ion channels open, leading to excitatory postsynaptic potentials (EPSPs) or inhibitory postsynaptic potentials (IPSPs).
What determines whether a new action potential is generated in the postsynaptic neuron?
The sum of EPSPs and IPSPs reaching the threshold at the axon hillock.
How is synaptic signaling terminated?
Through mechanisms that remove or degrade neurotransmitters, ensuring brief and precise signaling.
What is the role of presynaptic receptors in synaptic transmission?
They monitor released neurotransmitters to regulate further release.
What is the primary role of calcium (Ca²⁺) in synaptic transmission?
It triggers neurotransmitter release by facilitating synaptic vesicle fusion with the presynaptic membrane.
What is synaptic delay, and what causes it?
The brief pause between the arrival of an action potential and neurotransmitter release, caused by Ca²⁺ entry, vesicle fusion, and neurotransmitter diffusion.
How do neurotransmitters function as ligands?
They bind to specific receptor sites like a key fitting into a lock.
What effect does acetylcholine (ACh) have on the postsynaptic cell?
Excitatory: Opens Na⁺/K⁺ channels, depolarizing the cell.
Inhibitory: Opens Cl⁻ channels, hyperpolarizing the cell.
