Lecture 5 NROB60 Question And Answer

Flashcards based on lecture notes focusing on neurotransmission and neural circuits.

What is the focus of Lecture 5 by Dr. Marie Gadziola?

Fundamentals of neurotransmission and neural circuits.

What electrical property do neurons use to process information?

Electrical signals.

How do synapses contribute to neural communication?

They transmit information from one neuron to another.

What initiates the release of neurotransmitters?

Action potentials.

What are ions, and why are they significant for neurons?

Electrically charged molecules; they generate electrical potential.

What are cations?

Positively charged ions like Na+, K+, and Ca2+.

What are anions?

Negatively charged ions, for example, chloride (Cl-).

What is the typical resting potential of a neuron?

-65mV.

What primarily maintains the resting membrane potential in neurons?

Differential distribution of ions across the cell membrane.

How do ion channels differ?

They vary in selectivity for certain ions.

What role do sodium-potassium pumps play in neurons?

They maintain the differential distribution of K+ and Na+.

What does depolarization mean in the context of neuronal action?

A decrease in the electrical charge difference across the membrane.

What happens when an ion reaches its equilibrium potential?

The forces driving ions in and out of the cell are balanced.

What is the Nernst equation?

A mathematical function predicting an ion's equilibrium potential.

What is the absolute refractory phase?

A brief period of complete insensitivity to stimuli due to inactivated Na+ channels.

What is saltatory conduction?

The process by which action potentials jump from one node of Ranvier to another.

What is exocytosis in the context of neurotransmitter release?

The fusion of a synaptic vesicle with the presynaptic membrane.

What do presynaptic mechanisms influence?

Neurotransmission.

What determines how a postsynaptic neuron responds to neurotransmitters?

The type of receptor molecules present in its membrane.

What are ionotropic receptors?

Receptors that combine receptor and ion channel functions in one protein complex.

What are metabotropic receptors?

Receptors that activate G-proteins and modulate ion channels indirectly.

How do postsynaptic potentials (PSPs) affect action potential triggers?

EPSPs increase, whereas IPSPs decrease the probability of an action potential.

What is Dale’s Principle?

The principle that states one neuron releases one neurotransmitter.

What neurotransmitter is the most abundant excitatory neurotransmitter in the brain?

Glutamate.

What neurotransmitter is the most common inhibitory neurotransmitter in the brain?

GABA.

What role does acetylcholinesterase play in neurotransmission?

It breaks down acetylcholine (ACh) in the synaptic cleft.

What characterizes the action of biogenic amines?

They usually have slower, diffuse actions on neuron function.

What is the term for a drug that binds to a receptor and mimics the neurotransmitter?

Agonist.

What happens during the relative refractory phase?

Decreased sensitivity where only strong stimuli can trigger another action potential.

What allows for higher spatial precision at chemical synapses?

Point-to-point communication without direct current flow.

How do electrical synapses differ from chemical synapses?

They allow direct flow of current between neurons without a synaptic delay.

What is the outcome of synaptic connections mediated by electrical synapses?

Synchronized activity among populations of neurons.

What is spatial summation?

The algebraic sum of PSPs from different areas of input.

What is temporal summation?

The summation of PSPs that arrive at one location close in time.

How does an axoaxonic synapse influence neurotransmitter release?

It directly regulates the amount of neurotransmitter released from a targeted terminal.

What function do interneurons serve in the knee-jerk reflex?

They inhibit or excite motor neurons to control flexor and extensor muscles during the reflex.

What neurotransmitter system shows widespread loss in Alzheimer's disease?

Cholinergic neurons.

What happens when excitatory neurotransmitters bind to postsynaptic receptors?

Depolarization occurs, increasing the chance for an action potential.

What is the role of GAD in GABAergic neurons?

It converts glutamate into GABA.

What is a characteristic feature of peptide neurotransmitters?

They are composed of 3-36 amino acids.

What are common examples of small-molecule neurotransmitters?

Acetylcholine, amino acids, and biogenic amines.

How do neurotransmitters ensure rapid communication at synapses?

By being released in significant quantities and acting quickly on postsynaptic cells.

What underlies rapid synaptic transmission with amino acids?

The fast action of excitatory and inhibitory amino acid neurotransmitters.

What occurs during the release of neurotransmitters in chemical synapses?

Neurotransmitters bind to specific receptors on the postsynaptic membrane.

How do calcium ions contribute to neurotransmitter release?

Their influx triggers the fusion of vesicles with the presynaptic membrane.

What is the primary function of GABA receptors in the central nervous system?

To mediate inhibitory synaptic transmission.

What is the primary role of neurotransmitters?

To transmit signals across synapses from one neuron to another.

How can the same neurotransmitter result in different effects across various brain regions?

Different receptors may mediate different responses.

What is the principle neurotransmitter involved in neuromuscular junctions?

Acetylcholine.

What is typically the resting potential range for a neuron?

Between -40 to -90mV.

What is the significance of the axon hillock?

It reflects the integration of synaptic inputs.

What is the significance of the gap junctions in electrical synapses?

They allow direct, passive current flow between neurons.

How do cation channels influence membrane potential?

They allow positive ions to enter, causing depolarization.

What characterizes slow synaptic transmission compared to fast?

Involvement of G-proteins and second messenger systems.

What is unique about neurotransmitter co-localization or co-release?

Some neurons can release multiple types of transmitters.

What physiological responses do EPSPs and IPSPs generate?

EPSPs cause depolarization, while IPSPs cause hyperpolarization.

What defines the time scale of different synaptic potentials?

Fast (EPSPs) vs. slow (IPSPs) actions depending on the receptors activated.

What is a common method for studying action potentials in neurons?

Extracellular recordings.

What is the role of transporters in neurotransmitter clearance?

They reuptake neurotransmitters from the synaptic cleft back into the presynaptic terminal.

What is a major feature of ion channels in neurons?

They may be selective for specific ions such as Na+ or K+.

How do neurons maintain differential ion concentrations?

Through active transport mechanisms like sodium-potassium pumps.

What primarily influences the membrane potential of a neuron?

Differential ion concentrations and permeability of the membrane.

What does the term 'polarized' mean in relation to neuron membranes?

A potential difference exists across the neuron membrane.

What distinguishes myelinated from unmyelinated axons?

Myelinated axons conduct action potentials faster due to saltatory conduction.

How does the presence of neurotransmitter receptors influence synaptic response?

They determine the type of ion channels opened in postsynaptic membranes.

What are the consequences of a neurotransmitter's degradation?

It prepares the synapse for the next release and prevents unintentional signaling.

What indicates the efficiency of a synapse?

The existence of a short synaptic delay.

What happens during the overshoot phase of an action potential?

The inside of the cell becomes positive relative to the outside.

How do peptide neurotransmitters differ from small-molecule transmitters?

They are larger and composed of chains of amino acids.

What role does neurotransmitter recycling play in neuronal communication?

It allows for rapid replenishment and prevents neurotransmitter depletion.

How does the binding of neurotransmitters to receptors affect the postsynaptic neuron?

It leads to changes in excitability and potential alterations.

What is the typical time course of synaptic transmission?

Generally around 0.5 milliseconds.

What does the synaptic cleft contain?

Neurotransmitters released from the presynaptic neuron.

How are neurotransmitters classified?

Based on their chemical structure and function.

What influences the probability of an action potential being generated in postsynaptic neurons?

The amount and frequency of neurotransmitter released at synapses.

What happens to the action potential when the threshold is reached?

An action potential is generated and propagated along the axon.

What is the importance of ligand-binding domains in neurotransmitter receptors?

They determine the specificity of neurotransmitter binding.

What is the impact of ionotropic receptors on quick neuronal responses?

They allow for immediate changes in ion flow across the membrane.

What role does the electrical gradient play in ion movement?

It influences ions to move toward areas of opposite charge.

What changes occur in the membrane potential during an action potential?

Rapid depolarization followed by repolarization.

How do neurotransmitters that are co-released affect synaptic function?

They can lead to complex signaling cascades and varied effects on the postsynaptic cell.

What is the significance of the presynaptic terminal in neurotransmission?

It is where neurotransmitters are stored and released.

What characterizes the rapid phase of neurotransmission at excitatory synapses?

Fast depolarization leading to an increased likelihood of an action potential.

How can the same neurotransmitter perform different functions in different locations?

Depending upon the receptor type and its downstream signaling pathways.

What is the effect of activating inhibitory synapses on the postsynaptic neuron?

It decreases the likelihood of firing an action potential.

What type of neurotransmitter is serotonin, and what is its function?

A biogenic amine that modulates various physiological processes.

What type of physiological processes are affected by dopaminergic pathways?

They are involved in several functions, including mood, reward, and motor control.

Which neurotransmitter system is associated with attention and learning?

Cholinergic pathways.

What happens after the action potential reaches the presynaptic terminal?

Neurotransmitters are released into the synaptic cleft.

How does the body prevent overstimulation at the synapse?

By rapidly degrading or reuptaking neurotransmitters.

What happens to action potentials after a stimulation event?

They eventually return to baseline activity.

What is the major inhibitory neurotransmitter derived from glutamate?

GABA.

How are multiple effects achieved by the same neurotransmitter on postsynaptic neurons?

Through different receptor types and intracellular signaling pathways.

What neurotransmitter system is implicated in mood disorders?

Biogenic amines, including dopamine and serotonin.

What is a common feature of classical neurotransmitters?

They are synthesized and stored in presynaptic terminals and act on specific receptors.

What anatomical feature allows for efficiency in information transmission across neurons?

Chemical synapses with neurotransmitter release mechanism.

What measurement reflects a neuron's activity following a stimulus?

The frequency of action potentials.

What physiological roles do neuropeptides play in the nervous system?

They serve as modulators in synaptic transmission.

What is the advantage of having multiple receptor types for a single neurotransmitter?

Increases functional versatility in neural signaling.

What can result from disruptions in neurotransmitter signaling?

Neurological and psychiatric disorders.