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Questions and Answers
What is the primary function of Schwann cells in relation to axons?
What is the primary function of Schwann cells in relation to axons?
How do Schwann cells interact with unmyelinated axons?
How do Schwann cells interact with unmyelinated axons?
What structure do Schwann cells form along nerve axons?
What structure do Schwann cells form along nerve axons?
What is necessary for Schwann cells to effectively cover axons?
What is necessary for Schwann cells to effectively cover axons?
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What can be inferred about Schwann cell nuclei in relation to axons?
What can be inferred about Schwann cell nuclei in relation to axons?
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What causes the resting membrane potential in a neuron?
What causes the resting membrane potential in a neuron?
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Which type of ion channel is always open?
Which type of ion channel is always open?
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What limits nerve regeneration in the central nervous system (CNS)?
What limits nerve regeneration in the central nervous system (CNS)?
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What is the typical value of resting membrane potential in a neuron?
What is the typical value of resting membrane potential in a neuron?
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What happens when gated ion channels open?
What happens when gated ion channels open?
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What primary function does the Central Nervous System (CNS) serve?
What primary function does the Central Nervous System (CNS) serve?
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Which division of the Peripheral Nervous System (PNS) is responsible for controlling voluntary movements?
Which division of the Peripheral Nervous System (PNS) is responsible for controlling voluntary movements?
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What type of receptors monitor internal organs?
What type of receptors monitor internal organs?
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Which part of the Peripheral Nervous System regulates involuntary functions such as heart rate and digestion?
Which part of the Peripheral Nervous System regulates involuntary functions such as heart rate and digestion?
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What is an example of an effectors' response to motor commands?
What is an example of an effectors' response to motor commands?
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Which of the following statements about the Autonomic Nervous System (ANS) is true?
Which of the following statements about the Autonomic Nervous System (ANS) is true?
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Which type of muscle is NOT under the control of the Autonomic Nervous System?
Which type of muscle is NOT under the control of the Autonomic Nervous System?
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What type of sensory receptors are involved in monitoring smell and taste?
What type of sensory receptors are involved in monitoring smell and taste?
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What happens when the sodium channel activation gates open?
What happens when the sodium channel activation gates open?
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What is the initial effect on membrane potential when sodium ions enter the cytoplasm?
What is the initial effect on membrane potential when sodium ions enter the cytoplasm?
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What drives the influx of sodium ions into the cytoplasm during depolarization?
What drives the influx of sodium ions into the cytoplasm during depolarization?
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What is the state of the inner membrane surface during rapid depolarization?
What is the state of the inner membrane surface during rapid depolarization?
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What is the typical resting membrane potential before depolarization occurs?
What is the typical resting membrane potential before depolarization occurs?
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What occurs when the membrane potential reaches +30 mV?
What occurs when the membrane potential reaches +30 mV?
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What movement occurs as voltage-gated potassium channels open?
What movement occurs as voltage-gated potassium channels open?
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Which stage follows sodium channel inactivation during the action potential process?
Which stage follows sodium channel inactivation during the action potential process?
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What is the role of sodium channel inactivation in action potentials?
What is the role of sodium channel inactivation in action potentials?
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What is the primary consequence of potassium ions moving out of the cytosol?
What is the primary consequence of potassium ions moving out of the cytosol?
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Study Notes
Overview of the Nervous System
- The Nervous System is divided into the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).
- The CNS integrates, processes, and coordinates sensory data and motor commands.
- The PNS is divided into the afferent (sensory) and efferent (motor) divisions.
- The efferent division includes the somatic nervous system (SNS) and the autonomic nervous system (ANS).
- The ANS has two divisions: the parasympathetic and the sympathetic divisions.
Receptors and Effectors
- Receptors are responsible for monitoring internal and external environments, and include special sensory receptors, visceral sensory receptors, and somatic sensory receptors.
- Effectors are responsible for responding to efferent signals, and include: smooth muscle, cardiac muscle, glands, skeletal muscle, and adipose tissue.
Myelination
- Schwann cells form myelin sheaths around axons, enhancing the signal transmission.
- A series of Schwann cells is required to cover axons along their entire length.
Nerve Regeneration
- When an axon is injured, the portion distal to the injury degenerates.
- Schwann cells form a pathway for new axonal growth and wrap the new axon with myelin.
- Nerve regeneration in the CNS is limited due to chemicals that block growth and produce scar tissue.
Membrane Potential
- The flow of ions across cell membranes generates electrical currents.
- Differences in the number of cations (+) and anions (-) on either side of the membrane result in a membrane potential.
- Membrane potential is regulated by ion channels, which are membrane proteins.
Ion Channels
- Leakage channels are always open.
- Chemically gated channels open when specific chemicals bind.
- Voltage-gated channels open and close in response to changes in membrane potential.
- Mechanically gated channels open when the receptor receives physical pressure.
Resting Membrane Potential
- The resting membrane potential is maintained by the Na+–K+ ATPase (ion exchange pump).
- This pump actively carries 3 Na+ ions out and 2 K+ ions in, balancing passive forces of diffusion.
- The cell membrane is more permeable to K+ than to Na+ resulting in a resting potential of about -70 mV.
- The Na+–K+ ATPase actively maintains this resting potential using ATP.
Action Potential
- Action potentials are generated when a stimulus causes a change in the membrane potential
- When the membrane potential reaches the threshold, voltage-gated sodium channels open, leading to rapid depolarization.
- As the membrane potential approaches +30 mV, sodium channels inactivate and voltage-gated potassium channels open, allowing potassium ions to move out of the cell.
- This repolarization restores the membrane potential to its resting level.
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Description
This quiz provides an overview of the nervous system, including its division into the Central and Peripheral Nervous Systems. It covers receptor types, response mechanisms of effectors, and the role of myelination in signal transmission. Test your knowledge on these foundational concepts in neuroscience!
