Neuroscience: Synaptic Transmission Concepts

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Questions and Answers

What term did Charles Sherrington introduce in 1897 to describe the junction between neurons?

Synapse

What is the primary difference between electrical and chemical synapses in terms of transmission speed?

Electrical synapses provide very fast transmission, while chemical synapses are somewhat slower.

In the context of synaptic transmission, what role does the presynaptic neuron play?

The presynaptic neuron transmits information to the postsynaptic neuron.

What kind of potentials do chemical synapses generate upon activation?

Chemical synapses generate postsynaptic potentials (PSPs). Signup and view all the answers

What process involves several postsynaptic potentials occurring simultaneously to excite a neuron?

Synaptic integration Signup and view all the answers

What role do dendritic sodium channels play in the direction of electrical signals?

Dendritic sodium channels may carry electrical signals from the soma outward along the dendrites. Signup and view all the answers

How do inhibitory synapses affect the membrane potential of neurons?

Inhibitory synapses take the membrane potential away from the action potential threshold. Signup and view all the answers

What characterizes a hyperpolarizing IPSP in terms of membrane potential?

A hyperpolarizing IPSP occurs when the membrane potential is less negative than -65 mV. Signup and view all the answers

What is the principle of shunting inhibition?

Shunting inhibition involves the inhibition of current flow from the soma to the axon hillock. Signup and view all the answers

Why is chemical synaptic transmission important for understanding behavior?

Chemical synaptic transmission's diversity explains complex behavior and the impact of drugs and disorders. Signup and view all the answers

What structures form electrical synapses and what is their primary function?

Electrical synapses are formed by gap junctions, specifically connexons made up of six connexins, allowing the flow of ions between cells. Signup and view all the answers

What are the main differences between Gray's Type I and Type II synapses?

Gray's Type I synapses are asymmetrical and excitatory, while Gray's Type II synapses are symmetrical and inhibitory. Signup and view all the answers

List the basic steps involved in chemical synaptic transmission.

The steps include neurotransmitter synthesis, loading into vesicles, vesicle fusion to the presynaptic terminal, release into the synaptic cleft, binding to receptors, eliciting a response, and removal from the cleft. Signup and view all the answers

Name three types of neurotransmitters and give one example for each type.

Neurotransmitter types include amino acids (e.g., Glutamate), amines (e.g., Dopamine), and peptides (e.g., substance P). Signup and view all the answers

What is the role of neurotransmitter receptors in chemical synapse function?

Neurotransmitter receptors bind to neurotransmitters, eliciting biochemical or electrical responses in the postsynaptic cell. Signup and view all the answers

Describe the significance of the neuromuscular junction (NMJ) in synaptic transmission studies.

The NMJ was pivotal in establishing key principles of synaptic transmission due to its accessibility and functionality. Signup and view all the answers

What distinguishes an axosomatic synapse from an axodendritic synapse?

An axosomatic synapse is formed between an axon and the cell body, while an axodendritic synapse connects an axon to a dendrite. Signup and view all the answers

In the context of chemical synapses, what occurs during the removal of neurotransmitters from the synaptic cleft?

Neurotransmitters are cleared from the synaptic cleft to terminate the signal and prevent continuous activation of the postsynaptic cell. Signup and view all the answers

What is the equation that represents the ionic current flowing through synaptic channels?

IEPSP = N x po x g x (Vm - EEPSP) Signup and view all the answers

Explain the role of desensitization in synaptic transmission.

Desensitization refers to the decreased responsiveness of neurotransmitter receptors after prolonged exposure to a neurotransmitter. Signup and view all the answers

What do receptor agonists do in neuropharmacology?

Receptor agonists mimic the actions of naturally occurring neurotransmitters. Signup and view all the answers

Describe the significance of EPSP summation in neuronal function.

EPSP summation allows for multiple synaptic potentials to combine, producing significant depolarization in the postsynaptic neuron. Signup and view all the answers

How does dendritic length constant affect synaptic integration?

Dendritic length constant determines how far depolarization can spread along the dendrite before it dissipates. Signup and view all the answers

What are the two types of EPSP summation, and how do they differ?

The two types are spatial summation, where EPSPs occur simultaneously at different locations, and temporal summation, where EPSPs occur rapidly at the same synapse. Signup and view all the answers

What factors contribute to the driving force of ion flow through synaptic channels?

The driving force is affected by factors such as the reversal potential of EPSPs and the membrane potential. Signup and view all the answers

What is the importance of neurotransmitter recovery mechanisms?

Neurotransmitter recovery mechanisms are vital for modulating synaptic transmission and preventing excessive signaling. Signup and view all the answers

What is exocytosis and its role in neurotransmitter release?

Exocytosis is the process by which vesicles release their contents into the synaptic cleft, enabling neurotransmitter communication between neurons. Signup and view all the answers

Define 'quantum' in the context of synaptic vesicle transmission.

'Quantum' refers to the indivisible unit of neurotransmitter released from a synaptic vesicle during neurotransmission. Signup and view all the answers

Describe the function of ionotropic receptors in synaptic transmission.

Ionotropic receptors are transmitter-gated ion channels that allow ions to flow across the membrane, leading to changes in membrane potential. Signup and view all the answers

What is the significance of miniature postsynaptic potentials (mini) in neurotransmitter analysis?

Miniature postsynaptic potentials serve as indicators of the quantal release of neurotransmitters and help determine the efficacy of synaptic transmission. Signup and view all the answers

Explain how presynaptic calcium concentration affects neurotransmitter release.

Increased intracellular calcium concentration ([Ca2+]i) stimulates the exocytosis of vesicles, leading to the release of neurotransmitters. Signup and view all the answers

What results in an excitatory postsynaptic potential (EPSP)?

An EPSP results from a transient depolarization of the postsynaptic membrane caused by the release of an excitatory neurotransmitter. Signup and view all the answers

What are the main differences between excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs)?

EPSPs cause depolarization of the postsynaptic membrane, while IPSPs lead to hyperpolarization, counteracting excitatory signals. Signup and view all the answers

Define 'quantal analysis' and its purpose in neuroscience.

Quantal analysis is a method used to determine the number of synaptic vesicles released during neurotransmission by assessing the size of EPSPs. Signup and view all the answers

Describe the process of endocytosis in the context of synaptic vesicle recycling.

Endocytosis is the process that recovers the vesicle membrane after neurotransmitter release, allowing for the recycling of synaptic vesicles. Signup and view all the answers

How do the average number of channels opened by an agonist relate to neurotransmitter effects?

The average number of channels opened by an agonist determines the total conductance, thereby influencing the magnitude of EPSPs. Signup and view all the answers

Flashcards

Synaptic Transmission

The process of information transfer at a synapse.

Chemical Synapses

Slower synapses that generate postsynaptic potentials (PSPs).