Ch. 11 Fundamentals of the Nervous System and Nervous Tissue

Marieb - Human Anatomy & Physiology 11th Edition

Marieb, Hoehn11th EditionHuman Anatomy & PhysiologyISBN: 9780136874034당신이 사용하는 게 아니라요?교과서 변경

Marieb, Hoehn 11th Edition

Ch. 11 Fundamentals of the Nervous System and Nervous Tissue

문제 25

11장, 문제 25

Local anesthetics block voltage-gated Na⁺ channels. General anesthetics are thought to activate chemically gated Cl⁻ channels, thereby rendering the nervous system quiescent while surgery is performed. What specific process do anesthetics impair, and how does this interfere with nerve impulse transmission?

검증된 단계별 안내

Identify the specific process anesthetics impair: Both local and general anesthetics interfere with the generation and propagation of action potentials in neurons.

Understand how local anesthetics work: They block voltage-gated Na⁺ channels, preventing sodium ions from entering the neuron during depolarization, which stops the initiation and propagation of action potentials.

Understand how general anesthetics work: They activate chemically gated Cl⁻ channels, increasing chloride ion influx, which hyperpolarizes the neuron, making it less likely to reach the threshold needed to trigger an action potential.

Explain how these actions interfere with nerve impulse transmission: By preventing depolarization (local anesthetics) or by causing hyperpolarization (general anesthetics), the neurons cannot generate or propagate action potentials effectively, leading to a loss of sensation or consciousness.

Summarize the overall effect: Anesthetics impair the electrical excitability of neurons, thereby blocking the transmission of nerve impulses necessary for sensation and response during surgery.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Voltage-Gated Sodium Channels and Action Potential

Voltage-gated sodium channels open in response to membrane depolarization, allowing Na⁺ ions to enter the neuron. This influx initiates the rising phase of the action potential, which is essential for nerve impulse propagation along axons.

Chemically Gated Chloride Channels and Inhibition

Chemically gated chloride channels open in response to neurotransmitters like GABA, allowing Cl⁻ ions to enter the neuron. This influx hyperpolarizes the membrane, making it less likely to fire an action potential, thus inhibiting nerve activity.

Impairment of Nerve Impulse Transmission by Anesthetics

Local anesthetics block voltage-gated Na⁺ channels, preventing action potential initiation, while general anesthetics activate Cl⁻ channels, hyperpolarizing neurons. Both actions disrupt the generation and propagation of nerve impulses, leading to loss of sensation or consciousness.

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