82 Questions
Which of the following is responsible for the resting membrane potential in neurons?
Outward K+ current
Which of the following is responsible for depolarization during an action potential?
Inward Na+ current
Which of the following is responsible for the threshold voltage in an action potential?
Inward Na+ current
Which of the following is responsible for repolarization during an action potential?
Outward K+ current
According to the text, what is the conduction velocity for an alpha motor neuron?
100 meters/second
According to the text, what is the conduction velocity for C fibers responsible for pain?
1 meter/second
According to the text, what are the structural differences between alpha motor neurons and C fibers that contribute to the difference in their conduction velocity?
Alpha motor neurons are myelinated, while C fibers are not.
According to the text, why do neurons with a larger cross-sectional diameter conduct faster?
Larger diameter leads to increased conduction velocity because of decreased intracellular resistance.
Which of the following is true about the resting membrane potential (RMP) if extracellular Na+ concentration increases?
The RMP becomes slightly less negative
What happens to the RMP if extracellular K+ concentration suddenly increases?
The RMP becomes less negative
Which of the following is NOT a characteristic of action potentials?
Variable in voltage
Why do axons need action potentials instead of graded potentials to propagate signals long distances?
Graded potentials diminish over distance
Which of the following is true about selective serotonin reuptake inhibitors (SSRIs)?
SSRIs block the reuptake of serotonin from the synaptic cleft.
What would happen if the membrane suddenly became 100 times more permeable to Cl¯ ions than to any other ion?
The membrane potential would become clamped to ECl (e.g. -65 mV).
What is the effect of sodium channel inactivation on sodium channel activity during the after-hyperpolarization phase of the action potential?
Initially reduces Na+ conduction, but over time recovery from inactivation occurs.
How do neurons encode the intensity of a signal?
Increased frequency of action potentials.
Which ion's current is half blocked in the presence of this drug?
K+
What happens to the resting membrane potential (RMP) when the K+ current is half blocked?
It becomes more negative
What effect does doubling the Na/K pump activity have on the RMP?
It makes it more negative
By how much does the membrane potential hyperpolarize due to the electrogenic effects of the Na/K pump?
3 mV
What effect does the drug have on the delayed rectifiers?
It half blocks them
What happens to the duration of the action potential when the delayed rectifiers are half blocked?
It becomes longer
Which of the following statements is true about the delayed rectifier K+ channels?
If these channels open immediately upon depolarization, the depolarization would be slower and smaller.
Which of the following can initiate a subthreshold stimulus in a neuron that might lead to an action potential?
An electrical signal from a nearby part of the same neuron
Why does the membrane potential (Vm) become more negative than the resting membrane potential (RMP) during the after-hyperpolarization (AHP)?
An increased K+ current due to the delayed rectifier
What would be the equilibrium potential for the nicotinic acetylcholine receptor (nAChR) if it is equally permeable to Na+ and K+?
-17.5 mV
Which of the following is responsible for the afterhyperpolarisation (AHP) phase of the action potential?
Delayed rectifiers
What is the main transmembrane force acting on an ion during an action potential?
Electrochemical force
What is the equilibrium potential for Na+ in a typical cell?
~ +55 mV
Why is the resting membrane potential -70 mV despite the presence of positive K+ ions inside the cell?
K+ ions are balanced by negative ions inside the cell
Which ion is responsible for the resting membrane potential of -70 mV in a typical cell?
K+
What is the main transmembrane force acting on an ion at its equilibrium potential?
Chemical force
Which drug class blocks sodium channels as part of their mechanism of action?
Local anesthetics
What is the refractory period following an action potential?
A period of decreased excitability
What is the purpose of the nervous system?
Communication
What is the central nervous system responsible for?
Information processing
What is the peripheral nervous system responsible for?
Motor activation
Which part of the neuron is responsible for increasing conduction velocity?
Myelin
What is the main function of the pyramidal cell in the neocortex?
Thinking
Which type of neuron is responsible for coordination in the cerebellum?
Perkin G cell
What is the structure that contains the cell bodies of dorsal root ganglion cells?
Dorsal root ganglion
Which cells are able to divide throughout the lifespan and maintain neurons?
Glia
Which area of the brain is most rostral in the cerebral cortex?
Rostral
Which Broadman area corresponds to the sensory cortex?
Area 3
What is the main difference between neurons and glia?
Neurons form myelin sheaths
Which part of the neuron is primarily responsible for sensing and transmitting information?
Cell body
What is the purpose of the myelin sheath in neurons?
To insulate the axon electrically
What are the nodes of Ranvier in relation to the myelin sheath?
Gaps in the myelin sheath
What is the function of the axon terminals in a neuron?
To transmit electrical signals to other neurons
Which type of neuron is among the least numerous in the nervous system?
Bipolar neurons
What is the main characteristic of pseudo unipolar cells?
They have two poles but look like they have one
What is the key feature of chemical synapses?
They have a large gap between the presynaptic and postsynaptic neuron
What happens in divergent signaling?
A single neuron sends signals to multiple neurons
Which cells are more abundant in the nervous system compared to neurons?
Astrocytes
What is the function of glial cells?
Support and protect neurons
What is another name for glial cells?
Neural glia
What can be observed in the background of the image shown in the text?
Purple cells
What do glial cells do in relation to blood vessels?
Regulate blood flow
Which cells are shown as big cells in the image?
Neurons
What is the main function of glial cells in the nervous system?
Support and protection
Which part of the nervous system is derived from the ectoderm?
Central nervous system
What is the function of a ganglion in the nervous system?
Group of cell bodies outside the central nervous system
Which type of neurons occur only in the central nervous system?
Interneurons
What is the main difference between glia and neurons?
Glia have no action potentials, while neurons do
Which cells are able to divide throughout the lifespan and maintain neurons?
Glia
Which part of the neuron is responsible for receiving inputs?
Dendrites
What is the function of the myelin sheath in neurons?
To insulate the axon and increase conduction velocity
What is the main difference between dorsal and ventral in the brain?
Dorsal is the upper part of the brain, while ventral is the lower part
What is the main function of Broadman areas in the cerebral cortex?
To name and characterize different regions of the cerebral cortex
Which type of neuron is among the least numerous in the nervous system?
Bipolar neurons
What is the key feature of chemical synapses?
One-way transmission
What is the main function of convergent connections in the nervous system?
To integrate multiple inputs into a single neuron
What is the size of the synaptic cleft in a chemical synapse?
30 nanometers
Which part of the neuron is responsible for increasing conduction velocity?
Myelin sheath
What is the main difference between neurons and glia?
Neurons are responsible for transmitting signals, while glia provide support and insulation
What is the purpose of the myelin sheath in neurons?
To increase conduction velocity
What is the main transmembrane force acting on an ion during an action potential?
Electrical gradient
What is the main function of glial cells in the nervous system?
To support and protect neurons
What is the difference between glial cells and neurons?
Glial cells are more abundant than neurons
What are glial cells sometimes called?
Neural glia
Which type of cells are supporting cells in the nervous system?
Glial cells
What is the main difference between glial cells and neurons in terms of numbers?
There are more total glial cells than neurons
Test your knowledge on the consequences of immediate opening of "delayed rectifier" K+ channels upon depolarization. Explore the impact on repolarization during action potentials and understand the significance of the timing of delayed rectifier channel opening.
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