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Questions and Answers
What part of the nervous system performs information processing and integration?
What part of the nervous system performs information processing and integration?
Central nervous system
Which of the following allows us to consciously control our skeletal muscles?
Which of the following allows us to consciously control our skeletal muscles?
The somatic nervous system
Efferent nerve fibers may be described as motor nerve fibers.
Efferent nerve fibers may be described as motor nerve fibers.
True (A)
What is the name given to the electrical potential difference created by ion distribution across the membrane?
What is the name given to the electrical potential difference created by ion distribution across the membrane?
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Sodium and potassium ions can diffuse across the plasma membranes of all cells because of the presence of what type of channel?
Sodium and potassium ions can diffuse across the plasma membranes of all cells because of the presence of what type of channel?
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What does the sign and magnitude of the resting membrane potential value of -70 mV tell you?
What does the sign and magnitude of the resting membrane potential value of -70 mV tell you?
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Why is the plasma membrane much more permeable to K+ than to Na+?
Why is the plasma membrane much more permeable to K+ than to Na+?
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What factors influence the magnitude and direction of Na+ and K+ diffusion across the plasma membrane?
What factors influence the magnitude and direction of Na+ and K+ diffusion across the plasma membrane?
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What prevents the Na+ and K+ gradients from dissipating?
What prevents the Na+ and K+ gradients from dissipating?
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Where do most action potentials originate?
Where do most action potentials originate?
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What opens first in response to a threshold stimulus?
What opens first in response to a threshold stimulus?
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What characterizes depolarization, the first phase of the action potential?
What characterizes depolarization, the first phase of the action potential?
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What characterizes repolarization, the second phase of the action potential?
What characterizes repolarization, the second phase of the action potential?
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What event triggers the generation of an action potential?
What event triggers the generation of an action potential?
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What is the first change to occur in response to a threshold stimulus?
What is the first change to occur in response to a threshold stimulus?
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What type of conduction takes place in unmyelinated axons?
What type of conduction takes place in unmyelinated axons?
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An action potential is self-regenerating because __________.
An action potential is self-regenerating because __________.
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Why does regeneration of the action potential occur in one direction, rather than in two directions?
Why does regeneration of the action potential occur in one direction, rather than in two directions?
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What is the function of the myelin sheath?
What is the function of the myelin sheath?
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What changes occur to voltage-gated Na+ and K+ channels at the peak of depolarization?
What changes occur to voltage-gated Na+ and K+ channels at the peak of depolarization?
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In which type of axon will the velocity of action potential conduction be the fastest?
In which type of axon will the velocity of action potential conduction be the fastest?
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Which neurotransmitter(s) is/are the body's natural pain killer?
Which neurotransmitter(s) is/are the body's natural pain killer?
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What is the role of acetylcholinesterase?
What is the role of acetylcholinesterase?
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The substance released at axon terminals to propagate a nervous impulse is called a(n) ________.
The substance released at axon terminals to propagate a nervous impulse is called a(n) ________.
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Enkephalins and endorphins are peptides that act like morphine.
Enkephalins and endorphins are peptides that act like morphine.
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Study Notes
Central Nervous System & Somatic Nervous System
- The central nervous system is responsible for information processing and integration.
- The somatic nervous system enables conscious control over skeletal muscles.
Neuron Functionality
- Efferent nerve fibers are classified as motor nerve fibers.
- Resting membrane potential (RMP) indicates an electrical potential difference across the plasma membrane.
- RMP is typically -70 mV, showing the inside of the membrane is more negatively charged than the outside.
Ion Channels & Membrane Permeability
- Leak channels allow sodium (Na+) and potassium (K+) ions to diffuse across plasma membranes.
- The plasma membrane is more permeable to K+ due to a higher number of K+ leak channels compared to Na+ channels.
- The RMP is influenced by concentration gradients and the presence of leak channels.
Ion Gradient Maintenance
- The Na+-K+ ATPase pump maintains Na+ and K+ gradients, preventing dissipation.
Action Potential Initiation & Phases
- Most action potentials start at the initial segment of the neuron.
- Voltage-gated Na+ channels open in response to a threshold stimulus (-55 mV), leading to depolarization.
- Depolarization changes the membrane potential from negative to positive, peaking at +30 mV.
- Repolarization occurs as the membrane returns to resting potential, closing Na+ channels and opening K+ channels.
Action Potential Conduction
- The generation of an action potential is triggered by sufficient depolarization.
- Continuous conduction occurs in unmyelinated axons, while action potentials regenerate due to Na+ influx along the axon.
- Action potential conduction is unidirectional because of the inactivation of Na+ channels in segments just fired.
Myelin Sheath & Velocity
- Myelin sheaths significantly increase the speed of action potential conduction to axon terminals.
- Fastest conduction occurs in myelinated axons with the largest diameters.
Neurotransmitters & Their Functions
- Endorphins function as the body's natural painkillers.
- Acetylcholinesterase breaks down acetylcholine (ACh) shortly after its release to regulate synaptic transmission.
- Neurotransmitters are chemicals released at axon terminals to propagate nerve impulses.
- Enkephalins and endorphins, both peptides, mimic the effects of morphine, acting as pain relievers.
Studying That Suits You
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Description
Test your knowledge of neurons and the nervous system with these flashcards. Each card provides a question about key concepts, such as the central nervous system and the somatic nervous system, to help reinforce your understanding. Perfect for mastering anatomy and physiology!
