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Questions and Answers
What type of potential is generated at the dendrites of a neuron?
What type of potential is generated at the dendrites of a neuron?
Which of the following is NOT a characteristic of action potentials?
Which of the following is NOT a characteristic of action potentials?
What is the role of the myelin sheath in neuronal communication?
What is the role of the myelin sheath in neuronal communication?
Which of the following is responsible for the repolarization phase of an action potential?
Which of the following is responsible for the repolarization phase of an action potential?
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What is the primary method of communication between neurons?
What is the primary method of communication between neurons?
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How does the inactivation gate of voltage-gated sodium channels (VGSCs) contribute to the refractory period?
How does the inactivation gate of voltage-gated sodium channels (VGSCs) contribute to the refractory period?
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What is the primary role of the sodium-potassium pump (Na+-K+-ATPase) in action potential propagation?
What is the primary role of the sodium-potassium pump (Na+-K+-ATPase) in action potential propagation?
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Which of the following statements accurately describes the relationship between action potential frequency and stimulus strength?
Which of the following statements accurately describes the relationship between action potential frequency and stimulus strength?
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How does myelination contribute to the speed of action potential propagation?
How does myelination contribute to the speed of action potential propagation?
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How does the diameter of a nerve fiber influence the speed of action potential propagation?
How does the diameter of a nerve fiber influence the speed of action potential propagation?
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Why is the 'all-or-none' principle important for action potential transmission?
Why is the 'all-or-none' principle important for action potential transmission?
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What is the primary difference between graded potentials and action potentials?
What is the primary difference between graded potentials and action potentials?
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Which of the following best describes the role of voltage-gated potassium channels (VGPCs) in action potential propagation?
Which of the following best describes the role of voltage-gated potassium channels (VGPCs) in action potential propagation?
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Which of these statements about graded potentials is NOT true?
Which of these statements about graded potentials is NOT true?
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What is the primary function of the axon hillock?
What is the primary function of the axon hillock?
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Which of the following is NOT a characteristic of a graded potential?
Which of the following is NOT a characteristic of a graded potential?
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Which type of potential is responsible for initiating an action potential at the axon hillock?
Which type of potential is responsible for initiating an action potential at the axon hillock?
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What is the primary function of dendrites?
What is the primary function of dendrites?
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A drug that blocks the reuptake of a neurotransmitter would likely have what effect on synaptic transmission?
A drug that blocks the reuptake of a neurotransmitter would likely have what effect on synaptic transmission?
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Which of these statements about action potentials is true?
Which of these statements about action potentials is true?
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How do myelin sheaths affect the propagation of action potentials?
How do myelin sheaths affect the propagation of action potentials?
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Which of the following is an example of a graded potential?
Which of the following is an example of a graded potential?
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Which of the following statements about the neuron's trigger zone is true?
Which of the following statements about the neuron's trigger zone is true?
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Study Notes
Neuronal Physiology
- This study guide covers neuronal physiology, focusing on neurons, electrical signals, synapses, and the effects of drugs/diseases on synaptic activity.
Lecture Objectives
- Understand the structure of neurons and how they connect.
- Learn about graded potentials and action potentials as neuronal electrical signals.
- Explore how neurons transmit electrical signals across synapses.
- Examine the role of neurotransmitters and neuropeptides in synaptic transmission.
- Investigate how drugs and diseases affect synaptic activity.
Structure of the Neuron
- Dendrites: Input zone, increasing surface area for receiving signals, containing receptors for neurotransmitters. Initial graded potentials.
- Axon Hillock: Trigger zone, initiating action potentials; abundant voltage-gated sodium channels.
- Axon/Nerve Fiber: Single elongated tubular structure, often myelinated, carrying signals away from cell body.
- Cell Body (Soma): Nucleus, organelles, basic cell functions.
Neuronal Linkage
- Converging input: One neuron receives input from thousands of others.
- Diverging output: One neuron influences thousands of other neurons.
Graded Potentials
- Local changes in membrane potential (RMP) strength proportional to stimulus.
- Varying grades, not all-or-none
- examples include receptor potentials, postsynaptic potentials, pacemaker potentials, and slow-wave potentials.
- Spread passively as local currents.
- Die out over short distances.
Action Potentials
- Brief, rapid, large changes in membrane potential, where the inside of the cell becomes more positive.
- Differ from graded potentials by being all-or-none and propagating without diminishing strength.
- Generated at trigger zone.
- Serve as long-distance signals.
Action Potential Characteristics
- Conduction along an axon: Adjacent inactive areas are brought to threshold by local current flow, leading to action potential propagation.
- Propagation in one direction: Current flow is unidirectional.
- Refractory period: Absolute refractory period prevents backward propagation and limits the rate of action potential generation.
Action Potential Mechanisms and Channels
-
Voltage-Gated Sodium Channels:
- Rapid opening at threshold, followed by inactivation.
-
Voltage-Gated Potassium Channels:
- Delayed opening, repolarizing the cell.
Refractory Period
- Absolute Refractory Period: Impossible to generate another action potential due to sodium channels being inactivated.
- Relative Refractory Period: More difficult to generate an action potential due to potassium channels being open.
- Essential for unidirectional signal transmission.
Frequency of Action Potentials
- The frequency (how often) depends on stimulus strength.
- Stronger stimulus generates higher frequency than weak stimulus.
Speed of Action Potentials, Diameter and Myelin
- Speed increases with larger axon diameter.
- Myelination increases the speed of action potential propagation by saltatory conduction, jumping between nodes of Ranvier.
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Description
This quiz delves into the structure and function of neurons, focusing on the mechanisms of electrical signal transmission and synaptic activity. Understand key concepts such as graded potentials, action potentials, and the impact of drugs and diseases on synaptic functioning.
