Ch. 11 Fundamentals of the Nervous System and Nervous Tissue

Marieb - Human Anatomy & Physiology 7th Edition

Marieb, Hoehn7th EditionHuman Anatomy & PhysiologyISBN: 9780805359091Not the one you use?Change textbook

Marieb, Hoehn 7th Edition

Ch. 11 Fundamentals of the Nervous System and Nervous Tissue

Problem 21

Chapter 11, Problem 21

The effects of neurotransmitter binding are very brief. Explain.

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Understand that neurotransmitters are chemical messengers released from the presynaptic neuron into the synaptic cleft to transmit signals to the postsynaptic neuron or effector cell.

Recognize that the effects of neurotransmitter binding are brief because neurotransmitters are quickly removed from the synaptic cleft by mechanisms such as enzymatic degradation, reuptake into the presynaptic neuron, or diffusion away from the synapse.

Consider that this rapid removal prevents continuous stimulation of the postsynaptic receptors, allowing the neuron to reset and be ready for the next signal.

Note that the transient nature of neurotransmitter binding ensures precise control of neural communication, preventing overstimulation or prolonged activation of the postsynaptic cell.

Summarize that the brief effect is essential for proper nervous system function, enabling rapid and accurate transmission of information.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Neurotransmitter Binding

Neurotransmitter binding occurs when chemical messengers released from a neuron attach to specific receptors on a target cell, such as another neuron or muscle cell. This binding initiates a response, like opening ion channels or triggering intracellular signaling pathways, enabling communication between cells.

Synaptic Transmission Duration

The effects of neurotransmitter binding are brief because neurotransmitters are quickly removed from the synaptic cleft by reuptake, enzymatic degradation, or diffusion. This rapid clearance ensures that signals are transient, allowing neurons to reset and be ready for new signals.

Receptor Desensitization and Signal Termination

Receptors can become desensitized after neurotransmitter binding, reducing their responsiveness to continuous stimulation. Additionally, cellular mechanisms actively terminate the signal to prevent prolonged activation, maintaining precise control over neural communication and preventing overstimulation.

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Related Practice

Textbook Question

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?

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Textbook Question

When admitted to the emergency room, Sean was holding his right hand, which had a deep puncture hole in its palm. He explained that he had fallen on a nail while exploring a barn. Sean was given an antitetanus shot to prevent neural complications. Tetanus bacteria fester in deep, dark wounds, but how do their toxins travel in neural tissue?

Describe the events that must occur to generate an AP. Relate the sequence of changes in permeability to changes in the ion channels, and explain why the AP is an all-or-none phenomenon.

What is the polarized membrane state? How is it maintained? (Note the relative roles of both passive and active mechanisms.)

Since at any moment a neuron is likely to have thousands of neurons releasing neurotransmitters at its surface, how is neuronal activity (to fire or not to fire) determined?

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Textbook Question

Explain both the anatomical and functional divisions of the nervous system. Include the subdivisions of each.

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