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What is the name of the cells that create myelin sheaths around nerves in the peripheral nervous system?
What is the name of the cells that create myelin sheaths around nerves in the peripheral nervous system?
Schwann cells
What type of cells are responsible for myelinating nerve fibers in the central nervous system?
What type of cells are responsible for myelinating nerve fibers in the central nervous system?
Oligodendrocytes
What is the function of microglia cells?
What is the function of microglia cells?
Microglia help protect nerve cells by removing harmful substances.
Which of the following are functions of astrocytes? (Select all that apply)
Which of the following are functions of astrocytes? (Select all that apply)
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Neurotransmitters are substances that are released by neurons to communicate with other cells. Which of the following is NOT a function of neuroglia cells?
Neurotransmitters are substances that are released by neurons to communicate with other cells. Which of the following is NOT a function of neuroglia cells?
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The human nervous system is comprised of neurons and neuroglia cells.
The human nervous system is comprised of neurons and neuroglia cells.
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Neuroglia cells help in the electrical signal transmission in the nervous system.
Neuroglia cells help in the electrical signal transmission in the nervous system.
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Schwann cells are found in the Central Nervous System.
Schwann cells are found in the Central Nervous System.
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Oligodendrocytes are responsible for creating the myelin sheath in the peripheral nervous system.
Oligodendrocytes are responsible for creating the myelin sheath in the peripheral nervous system.
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A stimulus can be a mechanical signal, like hitting your knee with a mallet.
A stimulus can be a mechanical signal, like hitting your knee with a mallet.
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What is the name of the long, slender projection of a neuron that transmits nerve impulses?
What is the name of the long, slender projection of a neuron that transmits nerve impulses?
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What is the name of the junction between two neurons where a signal is transmitted?
What is the name of the junction between two neurons where a signal is transmitted?
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Nervous impulses are commonly transmitted through the neuron electrically using ion transport.
Nervous impulses are commonly transmitted through the neuron electrically using ion transport.
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What are the two main ions responsible for the propagation of nerve impulses?
What are the two main ions responsible for the propagation of nerve impulses?
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Electrical events in neurons are measured in milliseconds, and the potential changes are measured in microvolts.
Electrical events in neurons are measured in milliseconds, and the potential changes are measured in microvolts.
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What is the name of the pump that actively transports sodium and potassium ions across the neuronal membrane?
What is the name of the pump that actively transports sodium and potassium ions across the neuronal membrane?
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What does ATP stand for?
What does ATP stand for?
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What is the resting membrane potential of a neuron?
What is the resting membrane potential of a neuron?
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The resting membrane potential is maintained because of the unequal distribution of ions across the neuronal membrane.
The resting membrane potential is maintained because of the unequal distribution of ions across the neuronal membrane.
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The concentration of sodium ions is greater inside the cell than outside the cell during resting state.
The concentration of sodium ions is greater inside the cell than outside the cell during resting state.
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The concentration of potassium ions is greater outside the cell than inside the cell during resting state.
The concentration of potassium ions is greater outside the cell than inside the cell during resting state.
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The resting membrane potential is important for the initiation of action potentials because it provides a baseline for the membrane to be depolarized.
The resting membrane potential is important for the initiation of action potentials because it provides a baseline for the membrane to be depolarized.
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The membrane becomes hyperpolarized after the action potential.
The membrane becomes hyperpolarized after the action potential.
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What is the name of the process that occurs when the membrane potential of a neuron becomes more positive?
What is the name of the process that occurs when the membrane potential of a neuron becomes more positive?
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What is the name of the process that occurs when the membrane potential of a neuron returns to its resting potential?
What is the name of the process that occurs when the membrane potential of a neuron returns to its resting potential?
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What is the name of the process that occurs when the membrane potential of a neuron becomes more negative than its resting potential?
What is the name of the process that occurs when the membrane potential of a neuron becomes more negative than its resting potential?
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An action potential is an all-or-none event, meaning that it either occurs fully or not at all.
An action potential is an all-or-none event, meaning that it either occurs fully or not at all.
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If the stimulus is too low, there is no action potential.
If the stimulus is too low, there is no action potential.
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The amplitude of the action potential can vary according to the strength of the stimulus.
The amplitude of the action potential can vary according to the strength of the stimulus.
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The refractory period is a time when the neuron is unable to fire another action potential.
The refractory period is a time when the neuron is unable to fire another action potential.
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What is the name of the gap between the myelin sheath where the action potential can jump?
What is the name of the gap between the myelin sheath where the action potential can jump?
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Myelinated neurons transmit signals faster than unmyelinated neurons.
Myelinated neurons transmit signals faster than unmyelinated neurons.
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What is the role of myelin?
What is the role of myelin?
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The speed of nerve conduction is influenced by the diameter of the nerve. Thicker nerve fibers (axons) transmit impulses faster.
The speed of nerve conduction is influenced by the diameter of the nerve. Thicker nerve fibers (axons) transmit impulses faster.
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The speed of nerve conduction is influenced by temperature. Nerve conductions travel faster in warmer temperatures.
The speed of nerve conduction is influenced by temperature. Nerve conductions travel faster in warmer temperatures.
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Study Notes
Glial Cells
- Glial cells, also known as neuroglia cells, are supporting cells in the nervous system.
- They do not participate in neural transmission; their only role is to support neurons.
- Different types of glial cells include Schwann cells, oligodendrocytes, microglia, and astrocytes.
Types of Glial Cells
- Schwann cells: Create myelin sheaths around nerves in the peripheral nervous system (PNS).
- Oligodendrocytes: Create myelin sheaths around nerves in the central nervous system (CNS).
- Microglia: Help protect nerve cells by removing harmful substances.
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Astrocytes: Found throughout the brain, these cells have multiple functions:
- Connecting to blood vessels and aiding in the formation of the blood-brain barrier to protect the brain.
- Supporting nerve cell connections (synapses) and nerve cell surfaces.
- Producing substances that nourish nerve cells and regulate ion and neurotransmitter levels.
- Possessing receptors that respond to various neurotransmitters.
Neural Excitation and Conduction
- Neural stimulation can be electrical, chemical, or mechanical.
- Neural impulses are transmitted electrically via ion transport across the cell membrane, primarily involving sodium (Na+) and potassium (K+).
- Electrical events in neurons occur rapidly, measured in milliseconds (ms), with potential changes measured in millivolts (mV).
- Neural impulse conduction is slower than the speed of electricity.
Resting Membrane Potential
- The nerve cell membrane is polarized in its resting state due to active ion transport by the Na+/K+ ATPase pump.
- This pump actively transports 3 sodium ions (Na+) out of the cell and 2 potassium ions (K+) into the cell, resulting in a net positive charge outside the cell and a negative charge inside.
- The separation of charges creates the resting membrane potential, typically measured at -70mV.
- The concentrations of ions (K+, Na+, Cl-, Ca2+) on either side of the axon membrane are different.
Mechanism of Membrane Action Potential
- Action potential initiation typically begins with a stimulus causing the opening of Na+ channels inside the nerve cell
- The rapid influx of positive charge (Na+) causes Depolarization.
- Following depolarization, there's a rapid efflux of K+ out of the cell, leading to repolarization.
- The membrane potential briefly hyperpolarizes before returning to its resting state via the Na+/K+ ATPase pump.
Refractory Period
- Once an action potential begins, a brief refractory period occurs where the membrane is insensitive to further stimulation.
- There are two types: absolute and relative refractory periods.
- During the absolute refractory period, no stimulus, no matter how large, can trigger another action potential.
- During the relative refractory period, a stronger-than-usual stimulus is required to initiate another action potential.
Impulse Conduction
- Electrical impulses travel along neurons at variable speeds (1-120 m/s) influenced by factors such as nerve diameter, temperature, and the presence/absence of myelin.
- Myelinated neurons conduct impulses faster than unmyelinated neurons.
- Myelin sheath in myelinated neurons increases the speed of impulse conduction by insulating the axon and allowing depolarization only at the nodes of Ranvier. This results in "saltatory conduction".
All-or-None Law
- Action potentials either occur fully or not at all.
- The size of an action potential is independent of stimulus strength; only the frequency of action potentials can vary with stimulus strength.
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Description
Explore the fascinating world of glial cells, the unsung heroes of the nervous system. This quiz dives into the various types of glial cells, including Schwann cells, oligodendrocytes, microglia, and astrocytes, detailing their vital supportive roles and functions. Test your knowledge on how these cells contribute to the overall health and functioning of the nervous system.
