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Ch. 11 Introduction to the Nervous System and Nervous Tissue
All textbooksErin C. Amerman 2nd EditionCh. 11 Introduction to the Nervous System and Nervous TissueProblem 11.6a
Chapter 11, Problem 11.6a

Explain what would happen if depolarization of the trigger zone led to a negative feedback loop instead of a positive one. (Connects to Chapter 1)

Verified step by step guidance
1
Understand the concept of depolarization: Depolarization is the process by which the resting membrane potential becomes less negative (more positive), moving towards the threshold potential to initiate an action potential.
Review the role of the trigger zone: The trigger zone, typically located at the axon hillock, is where the action potential is initiated if the depolarization reaches the threshold level.
Differentiate between positive and negative feedback loops: A positive feedback loop amplifies changes, leading to a greater response, while a negative feedback loop reduces changes, promoting stability and returning the system to its set point.
Consider the effects of a negative feedback loop in depolarization: If depolarization led to a negative feedback loop, the initial depolarization would trigger mechanisms to counteract further depolarization, preventing the membrane potential from reaching the threshold needed to generate an action potential.
Analyze the implications for neural signaling: With a negative feedback loop, neurons would struggle to transmit signals effectively, as action potentials would be inhibited, potentially leading to impaired communication within the nervous system.

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Key Concepts

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

Depolarization

Depolarization refers to the process by which a neuron's membrane potential becomes less negative (or more positive) than the resting potential. This change is crucial for the initiation of action potentials, as it allows sodium ions to flow into the neuron, further propagating the electrical signal. Understanding depolarization is essential for grasping how neurons communicate and respond to stimuli.
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Feedback Loops

Feedback loops are processes in which the output of a system influences its own operation. In the context of neural activity, a positive feedback loop amplifies the initial signal, leading to a stronger response, while a negative feedback loop would inhibit or reduce the response. Recognizing the difference between these loops is vital for understanding how neural circuits regulate their activity and maintain homeostasis.
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Trigger Zone

The trigger zone is a specific area of a neuron, typically located at the axon hillock, where the summation of graded potentials occurs to initiate an action potential. This zone is sensitive to changes in membrane potential and plays a critical role in determining whether a neuron will fire. Understanding the function of the trigger zone is key to analyzing how signals are processed and transmitted in the nervous system.
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Related Practice
Textbook Question

Explain how an action potential is propagated down an axon in continuous conduction. Why is saltatory conduction faster than continuous conduction?

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Textbook Question

Albert, the patient in question 3, takes the drug lithium, which reduces the permeability of the neuronal axolemma to Na+ (that is, it allows fewer Na+ to enter the axon). Predict the effect this would normally have on his neuronal action potentials. Do you think this drug would be beneficial or harmful, considering his condition?

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Textbook Question

P​​redict the effect that tetrodotoxin would have on Albert's muscle fiber action potentials (see question 3). Would it affect end-plate potentials at the motor end plate? Why or why not? (Connects to Chapter 10)

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Textbook Question

Fill in the blanks: The______is the period of time during which it is impossible to stimulate a neuron to have an action potential, whereas the______ is the period of time during which a larger-than-normal stimulus is required to elicit an action potential.

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Textbook Question

Which of the following statements best describes saltatory conduction?


a. Every section of the axolemma must be depolarized and triggered to generate an action potential.

b. The internodes must generate action potentials.

c. The dendrites and cell bodies propagate EPSPs toward the trigger zone.

d. Only the nodes of Ranvier must generate action potentials.

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Textbook Question

Identify the following as properties of electrical synapses (ES), chemical synapses (CS), or both (B).           


a. ______The plasma membranes of presynaptic and postsynaptic neurons are joined by gap junctions.          

b. ______Transmission is unidirectional and delayed.          

c. ______A presynaptic neuron and a postsynaptic neuron are involved.          

d. ______The use of neurotransmitters packaged into synaptic vesicles is required.          

e. ______Transmission is nearly instantaneous and bidirectional.

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