Question

List the steps involved in synaptic transmission
Compare and contrast an EPSP and an IPSP

Answer 1

Synaptic transmission involves several steps including the generation of an electric signal in the presynaptic neuron, release of neurotransmitter molecules, and binding of neurotransmitters to receptors on the postsynaptic neuron. EPSPs depolarize the postsynaptic neuron towards the threshold for firing an action potential, while IPSPs hyperpolarize it away from the threshold. The net effect of EPSPs and IPSPs determines whether an action potential is triggered in the postsynaptic neuron.

Step-by-step explanation:

Steps involved in synaptic transmission:

1. Electric signal (action potential) is generated in the presynaptic neuron.
2. Neurotransmitter molecules are released from the presynaptic neuron into the synapse.
3. Neurotransmitters bind to receptors on the postsynaptic neuron.
4. If the neurotransmitter is excitatory, it opens ligand-gated ion channels that allow positive ions (such as Na+) to enter the postsynaptic neuron, creating an excitatory postsynaptic potential (EPSP).
5. If the neurotransmitter is inhibitory, it opens ligand-gated ion channels that allow negative ions (such as Cl-) to enter the postsynaptic neuron, creating an inhibitory postsynaptic potential (IPSP).
6. If the net effect of EPSPs exceeds the threshold for excitation, an action potential is triggered in the postsynaptic neuron

Comparison between EPSP and IPSP:

EPSP: Excitatory Postsynaptic Potential

• Depolarizes the postsynaptic neuron towards the threshold for firing an action potential.
• Usually caused by the opening of ligand-gated ion channels that allow positive ions (such as Na+) to enter the postsynaptic neuron.
• Increases the likelihood of the postsynaptic neuron firing an action potential.

IPSP: Inhibitory Postsynaptic Potential

• Hyperpolarizes the postsynaptic neuron, moving its membrane potential further away from the threshold for firing an action potential.
• Usually caused by the opening of ligand-gated ion channels that allow negative ions (such as Cl-) to enter the postsynaptic neuron.
• Decreases the likelihood of the postsynaptic neuron firing an action potential.