Neuroscience: Postsynaptic Responses

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What causes the depolarization in a postsynaptic neuron during EPSP?

Decrease in Na+ efflux

Decrease in K+ influx

Increase in Ca+ influx (correct)

Increase in Cl- influx

Which neurotransmitter is the most common excitatory neurotransmitter in the central nervous system?

Serotonin

GABA

Glutamate (correct)

Dopamine

What is the outcome of spatial summation in synaptic transmission?

Facilitation of individual synaptic knobs to reach firing level (correct)

Decrease in neurotransmitter release

Local hyperpolarization

Inhibition of the postsynaptic neuron

What describes the timing of temporal summation in synaptic transmission?

Successive activation of the same synaptic knob Signup and view all the answers

How does IPSP affect the postsynaptic neuron?

Results in hyperpolarization Signup and view all the answers

What happens to a neurotransmitter during its inactivation?

It is degraded or reabsorbed Signup and view all the answers

What is the primary effect of cation channels when neurotransmitters bind to them?

Influx of Na+ ions leading to depolarization Signup and view all the answers

Which neurotransmitter is commonly associated with the activation of anion channels?

Glycine Signup and view all the answers

In the context of EPSP, what occurs after depolarization begins in response to an afferent impulse?

It reaches a peak within 1 to 1.5 ms Signup and view all the answers

What role do second messengers play in synaptic transmission?

They lead to prolonged post-synaptic excitation or inhibition Signup and view all the answers

What determines whether the postsynaptic membrane undergoes depolarization or hyperpolarization?

The specific type of ion channel activated and ion movement Signup and view all the answers

How is the activity of neurotransmitters in the synaptic cleft typically terminated?

Via reuptake by surrounding neurons or glial cells Signup and view all the answers

Which process contributes to hyperpolarization during an IPSP?

Increased efflux of K+ Signup and view all the answers

What is the result of the temporal summation of IPSPs?

It leads to a stronger inhibitory effect on the postsynaptic neuron. Signup and view all the answers

Which neurotransmitter is primarily associated with generating IPSPs?

GABA Signup and view all the answers

What occurs during the mechanism resulting in slow IPSPs?

Increased K+ conductance Signup and view all the answers

Which of the following methods is NOT involved in the inactivation of neurotransmitters from the synaptic cleft?

Active transport into the synaptic vesicles Signup and view all the answers

What determines the membrane potential of the postsynaptic neuron?

The algebraic sum of EPSPs and IPSPs Signup and view all the answers

Which factor increases Cl- influx during an IPSP?

Opening of Cl- channels Signup and view all the answers

In the context of synaptic transmission, what does spatial summation primarily involve?

Simultaneous activation of multiple synapses on the same neuron. Signup and view all the answers

Study Notes

Inhibitory Post Synaptic Potential (IPSP)

IPSP decreases neuron excitability to stimuli.
Produced by inhibitory neurotransmitters (NTs) such as GABA and glycine.
Ionic mechanisms involved:
- Opening of Cl- channels increases Cl- influx.
- Opening of K+ channels increases K+ efflux.
- Closing of Na+ channels decreases Na+ influx.
- Closing of Ca2+ channels decreases Ca2+ influx.
Results in hyperpolarization, making the neuron more negative.
Increased concentration of anions in the postsynaptic neuron leads to hyperpolarization.

Summation of IPSP

Spatial Summation: Multiple active synaptic knobs enhance each other’s effects.
Temporal Summation: Repeated activity of one knob in quick succession creates a new IPSP before the previous one decays.

Slow EPSP & IPSP

Occur in autonomic ganglia, cardiac muscle, smooth muscle, and cortical neurons.
Latency ranges from 100 to 500 ms and can last several seconds.
Slow EPSP is induced by decreased K+ conductance.
Slow IPSP is induced by increased K+ conductance.

Inactivation of Neurotransmitters

Released neurotransmitters in the synaptic cleft are quickly inactivated by:
- Diffusion out of the cleft.
- Enzymatic degradation.
- Reuptake into the presynaptic terminal.

Generation of Action Potential in Postsynaptic Neuron

Membrane potential fluctuates due to the balance of excitatory and inhibitory inputs.
The overall effect of excitatory post synaptic potentials (EPSPs) and IPSPs determines neuron excitability.
Glutamate is the primary excitatory neurotransmitter in the CNS.

Ionic Basis of EPSP

Opening of Na+ channels increases Na+ influx.
Opening of Ca2+ channels increases Ca2+ influx.
Closing of Cl- channels decreases Cl- influx.
Closing of K+ channels decreases K+ efflux.
Results in depolarization, making the neuron more positive (excited).

EPSP and IPSP Summation

Spatial Summation: Concurrent activation of multiple synaptic knobs leads to reaching the threshold for action potential (AP).
Temporal Summation: Rapid succession of stimulation from one knob generates sufficient EPSPs to reach the threshold.

Definition of EPSP and IPSP

EPSP refers to potential change toward depolarization.
Hyperpolarization in the postsynaptic neuron is indicative of IPSP.
Hyperpolarization peaks at 1.5 - 2 ms after impulse and subsequently declines.

Mechanism of Neurotransmitter Action

Neurotransmitters bind to ligand-gated ion channels:
- Cation channels (e.g., glutamate) lead to Na+ influx and depolarization (EPSP).
- Anion channels (e.g., glycine, GABA) lead to Cl- influx and hyperpolarization (IPSP).
Neurotransmitters activate G protein-linked receptors, initiating processes that alter ionic permeability, causing prolonged excitatory or inhibitory effects.

Synaptic Potential

Synaptic potentials (EPSP and IPSP) determine the membrane potential of the postsynaptic neuron.
Depending on ionic flow, the potential may shift towards depolarization or hyperpolarization, creating signals essential for neuron communications.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the intricate processes that occur in postsynaptic cells when neurotransmitters (NT) bind to receptors. This quiz covers the mechanisms of excitatory (EPSP) and inhibitory (IPSP) synaptic transmissions through ligand-gated ion channels and second messengers. Test your understanding of neural communication dynamics.