Neuroscience: Postsynaptic Potentials

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Questions and Answers

What are the types of postsynaptic potentials?

Excitatory (EPSP)

Inhibitory (IPSP)

Both A and B (correct)

None of the above

What does EPSP stand for?

Excitatory Postsynaptic Potential

What does IPSP stand for?

Inhibitory Postsynaptic Potential

What occurs after an action potential travels down an axon?

Neurotransmitter release affecting the postsynaptic cell. Signup and view all the answers

What are the summation types for EPSP and IPSP?

Both A and B Signup and view all the answers

What is Spatial Summation?

Multiple EPSP and IPSP from different locations converge at the Axon Hillock at the same time. Signup and view all the answers

What is Temporal Summation?

EPSP and IPSP arriving at the Axon Hillock close together in time. Signup and view all the answers

What happens during the Absolute Refractory Period?

Na+ channels are activated. Signup and view all the answers

What is the first chemical event at the synapse?

Neuron synthesizes neurotransmitters Signup and view all the answers

What happens during re-uptake?

Neurotransmitters are taken back into the presynaptic neuron. Signup and view all the answers

What is an Autoreceptor?

A receptor sensitive to its own neurotransmitter. Signup and view all the answers

What is a Presynaptic Receptor?

A receptor sensitive to a different neurotransmitter. Signup and view all the answers

What characterizes an Axoaxonic Synapse?

Inhibition or facilitation of presynaptic cell activity. Signup and view all the answers

What occurs during Postsynaptic Inhibition?

Neurons release chemicals that modulate neurotransmitter release. Signup and view all the answers

What is the effect of Ionotropic neurotransmitter action?

Activates receptor with immediate effect Signup and view all the answers

What defines Metabotropic neurotransmitter action?

Multistep process affecting polarization Signup and view all the answers

Study Notes

Types of Postsynaptic Potentials

Two main types: Excitatory Postsynaptic Potential (EPSP) and Inhibitory Postsynaptic Potential (IPSP).

Excitatory Postsynaptic Potential (EPSP)

EPSP leads to the depolarization of the postsynaptic membrane.
It moves the neuron closer to firing an action potential.
Occurs when negatively charged ions exit and positively charged ions enter the cell.

Inhibitory Postsynaptic Potential (IPSP)

IPSP results in hyperpolarization of the postsynaptic membrane.
It moves the neuron farther away from firing an action potential.
Occurs when more negatively charged ions are added to a negatively charged receptor cell.

Postsynaptic Potential

Characterizes the change in the postsynaptic cell's electrical state after neurotransmitter release following an action potential.

EPSP and IPSP Properties

Both types travel from their site of generation as graded potentials.
They exhibit cable properties allowing them to influence the postsynaptic neuron.

Axon Hillock

The location where EPSP and IPSP are summed.
Determines if the threshold for an action potential is reached through various summation methods.

EPSP/IPSP Summation Types

Types include spatial summation and temporal summation, which describe how signals combine at the axon hillock.

Spatial Summation

Occurs when multiple EPSPs and IPSPs from different sites converge at the axon hillock simultaneously.

Temporal Summation

Involves EPSPs and IPSPs arriving at the axon hillock in quick succession, allowing them to cumulatively influence the membrane potential.

Absolute Refractory Period

Characterizes the state when Na+ channels are activated and can’t respond to further stimuli.

Chemical Events at the Synapse

Sequence of events critical for neuron communication across the synapse.

First Chemical Event

The synthesis of neurotransmitters by the neuron.

Second Chemical Event

Storage or transport of neurotransmitters within axon terminals.

Third Chemical Event

An action potential triggers neurotransmitter release into the synaptic cleft.

Fourth Chemical Event

Neurotransmitters travel across the synaptic cleft and bind to receptors on the postsynaptic membrane.

Fifth Chemical Event

Neurotransmitters detach from receptors; this process is controlled and time-limited.

Sixth Chemical Event

Neurotransmitters are either taken back into the presynaptic neuron, diffuse away, or become inactivated, a process known as "re-uptake."

Seventh Chemical Event (Optional)

Postsynaptic cells may send feedback to slow neurotransmitter release, preventing excessive excitation.

Ionotropic Receptors

Directly activate and open ion channels, leading to immediate changes in the postsynaptic cell.

Metabotropic Receptors

Engage in a multistep process that results in the postsynaptic cell's depolarization or hyperpolarization.

Modulation of Neurotransmitter Release

Mechanisms include autoreceptors, presynaptic receptors, axoaxonic synapses, and postsynaptic inhibition.

Autoreceptors

Receptors sensitive to the neuron's own neurotransmitter that provide feedback to regulate release.

Presynaptic Receptors

Receptors that respond to different neurotransmitters than their own.

Axoaxonic Synapse

Modulates presynaptic activity through the release of different neurotransmitters, leading to inhibition or facilitation.

Postsynaptic Inhibition

Mechanism where chemicals from a neuron travel back to the presynaptic terminal to reduce the release of its neurotransmitters.

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Description

This quiz focuses on the two main types of postsynaptic potentials: Excitatory (EPSP) and Inhibitory (IPSP). You will explore their properties, how they affect neuron firing, and the physiological mechanisms involved. Test your understanding of these crucial concepts in neuroscience.