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Questions and Answers

What is a potential consequence of excessive inhibitory neurotransmitter activity in the central nervous system?

Excessive dopamine production resulting in schizophrenia.
Sedation and impaired cognitive function. (correct)
Overexcited neurons leading to anxiety.
Increased synaptic plasticity and enhanced learning.

How do Monoamine Oxidase Inhibitors (MAOIs) affect neurotransmitter levels in the synapse, and for what condition are they primarily used?

MAOIs prevent the breakdown of monoamines, treating depression and anxiety. (correct)
MAOIs increase serotonin production, treating appetite disorders.
MAOIs degrade monoamines, treating schizophrenia.
MAOIs block the reuptake of catecholamines, treating Parkinson's disease.

Which of the following best describes the clinical application of antagonists that block acetylcholine (ACh) receptors at the neuromuscular junction?

Enhancing muscle contractions to treat muscular dystrophy.
Increasing dopamine release to alleviate Parkinson's symptoms.
Stimulating nerve signaling to treat autism.
Inhibiting muscle contraction, acting as a muscle relaxant. (correct)

What is the potential consequence of long-term amphetamine use, considering its effects on norepinephrine pathways and the sympathetic nervous system?

Increased blood pressure, elevated heart rate, and jitters due to stimulation of the sympathetic nervous system. (D) Signup and view all the answers

What is the primary function of acetylcholine (ACh) at the neuromuscular junction (NMJ)?

Initiating muscle contractions through binding to receptors on muscle cells. (D) Signup and view all the answers

How does the degradation of dopamine-producing neurons in the nigrostriatal system primarily manifest clinically, and what is a common treatment approach?

Tremors and motor dysfunction, potentially treated with MAO inhibitors. (A) Signup and view all the answers

Given the duality of dopamine's functions, what potential challenge arises when treating conditions related to dopamine imbalances?

Addressing emotional reward imbalances may inadvertently trigger or exacerbate motor dysfunction symptoms. (C) Signup and view all the answers

What is the likely effect of a drug that selectively stimulates norepinephrine pathways in the central nervous system?

Increased brain neuron stimulation and behavioral activation. (B) Signup and view all the answers

Which glial cell type is primarily responsible for forming the myelin sheath around axons in the central nervous system (CNS), and what is a potential consequence if these cells are damaged?

Oligodendrocytes; damage can lead to neurodegenerative diseases such as multiple sclerosis. (B) Signup and view all the answers

How do astrocytes contribute to the function of the blood-brain barrier (BBB), and why is this significant for treating neurological disorders such as meningitis?

They influence the permeability of the barrier by releasing molecules that control diffusion. This makes it difficult for many drugs to effectively treat infections like meningitis. (B) Signup and view all the answers

In the context of neuronal communication, what is the primary functional difference between a sensory neuron and a motor neuron, and where are their cell bodies typically located?

Sensory neurons carry signals from receptors to the CNS and have cell bodies in the PNS, while motor neurons transmit signals from the CNS to muscles or glands (effectors) and have cell bodies either in the CNS or PNS. (D) Signup and view all the answers

During an action potential, how do the movements of sodium ($Na^+$) and potassium ($K^+$) ions across the neuronal membrane contribute to depolarization and repolarization, respectively?

$Na^+$ influx causes depolarization, while $K^+$ efflux causes repolarization. (C) Signup and view all the answers

What role do interneurons play within the central nervous system (CNS), and how does this differ from the function of sensory and motor neurons?

Interneurons integrate sensory information within the CNS to formulate responses, distinguishing them from sensory neurons that carry information to the CNS and motor neurons that carry responses to effectors. (D) Signup and view all the answers

How do Schwann cells facilitate rapid nerve impulse conduction in the peripheral nervous system (PNS), and what structural features are critical to this function?

Schwann cells produce myelin sheaths with neurilemma and Nodes of Ranvier, which enable saltatory conduction. (B) Signup and view all the answers

What is the functional significance of the axon hillock in a neuron, and how does it contribute to the generation of action potentials?

The axon hillock is the region where the action potential is initiated due to its high concentration of voltage-gated ion channels. (B) Signup and view all the answers

During hyperpolarization, how does the change in membrane potential affect the neuron's excitability, and what ionic event is primarily responsible for this state?

It decreases neuronal excitability due to an excessive efflux of potassium ions. (B) Signup and view all the answers

During the repolarization phase of an action potential, what specific mechanism directly contributes to the membrane potential becoming more negative?

Inactivation of sodium channels and continued efflux of potassium ions ($K^+$) through voltage-gated channels. (B) Signup and view all the answers

Which of the following scenarios accurately describes the 'all or none' principle of action potentials?

If the stimulus is strong enough to reach threshold, an action potential of fixed voltage and duration is generated, regardless of any further increases in stimulus strength. (D) Signup and view all the answers

How does myelin sheath contribute to the increased speed of action potential propagation in myelinated axons?

By preventing ion leakage and allowing action potentials to 'jump' between Nodes of Ranvier (saltatory conduction). (C) Signup and view all the answers

What distinguishes anterograde axonal transport from retrograde axonal transport in neurons?

Anterograde transport moves substances away from the cell body, whereas retrograde transport moves substances toward the cell body (often including viruses). (A) Signup and view all the answers

Which structural characteristic is most closely associated with sensory neurons?

Unipolar structure with a T-shaped configuration. (B) Signup and view all the answers

Under what specific conditions is axon regeneration most likely to occur?

In the peripheral nervous system (PNS), provided the cell body is intact and Schwann cells form a regeneration tube. (D) Signup and view all the answers

In contrast to synapses found in the central nervous system (CNS), how do synapses in the peripheral nervous system (PNS) differ in their typical target cells?

PNS synapses typically target muscles, glands, or other effector cells, rather than other neurons. (A) Signup and view all the answers

What is the fundamental difference in the mechanism of signal transmission between electrical and chemical synapses?

Electrical synapses use direct physical connections (gap junctions) for ion flow, whereas chemical synapses use neurotransmitters that diffuse across a synaptic cleft. (B) Signup and view all the answers

How does the opening of voltage-gated calcium channels at the axon terminal directly facilitate neurotransmitter release?

Calcium ions trigger the fusion of neurotransmitter-filled vesicles with the presynaptic membrane, leading to exocytosis. (D) Signup and view all the answers

What critically distinguishes ligand-gated ion channels from G-protein-coupled receptors in terms of their mechanism of action?

Ligand-gated channels directly open ion channels upon neurotransmitter binding, whereas G-protein-coupled receptors use secondary messengers to indirectly open ion channels. (A) Signup and view all the answers

How does spatial summation differ mechanistically from temporal summation in the context of postsynaptic potential integration?

Spatial summation occurs when multiple inputs arrive simultaneously at different locations on the postsynaptic neuron, whereas temporal summation occurs when repeated inputs arrive in close succession from the same input. (B) Signup and view all the answers

How does divergent neural circuitry differ from convergent neural circuitry in terms of signal propagation?

Divergent circuits amplify a signal by spreading it to multiple pathways, whereas convergent circuits integrate multiple signals into a single pathway. (B) Signup and view all the answers

What is the primary mechanism underlying long-term depression (LTD) in synaptic plasticity?

Reduced synaptic efficiency from underused stimulus, potentially involving endocannabinoid release to suppress neurotransmitter release. (C) Signup and view all the answers

How does synaptic inhibition prevent the postsynaptic neuron from reaching threshold and firing an action potential?

By closing excitatory ($Na^+$ or $Ca^{2+}$) channels, reducing the likelihood of depolarization, and potentially opening $K^+$ or $Cl^-$ channels. (B) Signup and view all the answers

How do opioids reduce pain at the synaptic level?

By inhibiting the release of excitatory neurotransmitters such as Substance P, which relays pain signals. (B) Signup and view all the answers

Flashcards

Neuron

Basic nerve cell with a cell body, axon, and dendrites; transmits electrical signals.

Cell Body (Neuron)

Main hub with nucleus and organelles for cell functions; CNS: nuclei, PNS: ganglia