43 Questions
What is the main reason for the electrical difference (voltage) across the cell membrane?
The accumulation of excess positive charges just outside the cell membrane and excess negative charges immediately inside the cell membrane.
What is the main factor that contributes to the resting membrane potential?
The concentration gradient of ions across the cell membrane.
What is the main reason for the higher permeability of the cell membrane to potassium ions (K⁺) compared to sodium ions (Na⁺) at rest?
The cell membrane has more potassium leak channels than sodium leak channels.
What is the typical resting membrane potential in mammalian neurons?
$-70$ mV
Which of the following statements about the equilibrium potential for an ion species is correct?
The equilibrium potential is the potential at which the net flow of the ion across the membrane is zero.
What is the primary function of neuroglia or glial cells in the nervous system?
To provide structural and metabolic support for neurons
Which type of neuron has a single stem axonal process that branches to form two processes?
Pseudounipolar neuron
Which of the following is a major functional unit of the nervous system?
Neurons
What is the primary role of the axon hillock or trigger zone in a neuron?
To generate and propagate the action potential
Which type of neuron is responsible for transmitting information from the brain or spinal cord to muscles and glands?
Motor neuron
What is the primary function of the myelin sheath surrounding the axons of some neurons?
To enhance the speed of information transfer
What is the primary function of the Na+, K+ pump (ATPase) in cell membranes?
Pumps Na+ out of the cell and K+ into the cell against their concentration gradients
How do synaptic signals from another cell change the membrane potential of a neuron or muscle cell?
Synaptic signals open or close ion-selective channels, changing the membrane potential
What is the difference between an EPSP (excitatory postsynaptic potential) and an IPSP (inhibitory postsynaptic potential)?
An EPSP makes the inside of the cell more positive, increasing the chance of reaching the threshold and triggering an action potential, while an IPSP makes it more negative
What is the primary reason that the change in membrane potential caused by an EPSP or IPSP only lasts for a short time (milliseconds)?
The neurotransmitter is quickly removed from the synapse, and the ion channels close again
What is the relationship between the resting membrane potential and the ability of a cell to generate an action potential?
The resting membrane potential can be changed by synaptic signals, which can then influence the cell's ability to reach the threshold and generate an action potential
What is the primary function of the Na+, K+ pump (ATPase) in maintaining the resting membrane potential of a cell?
The Na+, K+ pump actively pumps Na+ out of the cell and K+ into the cell, creating a concentration gradient that drives the resting membrane potential
What is responsible for the propagation of action potentials down the axon?
Voltage-gated Na+ channels
What factor influences the speed of action potential conduction in the nervous system?
Degree of myelination and axon diameter
How do myelinated axons contribute to faster conduction velocity?
By allowing the current to jump between nodes (saltatory conduction)
What ion enters the cell during the opening of Ca2+ voltage-gated channels at the axon terminal?
Calcium (Ca2+)
Which class of neurotransmitters includes GABA and glutamate?
Amino acids and derivatives
What is responsible for releasing neurotransmitters into the synaptic cleft by exocytosis?
Synaptic vesicles
Which organelle is primarily responsible for producing ATP in neurons?
Mitochondria
What is the function of the axon hillock and initial axon segment?
Integrate different signals and generate action potentials
What is the function of the myelin sheath?
Facilitate electrical insulation and saltatory conduction
What are the functions of dendritic spines?
Contain specialized receptors to recognize neurotransmitters
What determines the conduction velocity of myelinated axons?
The diameter of the axon and the length of the internodes
What is the function of the presynaptic terminal?
Release neurotransmitters to signal adjacent cells
Which of the following is NOT one of the 6 major classes of neurotransmitters?
Alkaloids
Which type of neuron is responsible for transmitting information from receptors in sensory organs towards the brain or spinal cord?
Sensory neuron
Which of the following is NOT one of the three major factors contributing to the resting membrane potential?
The electrical attraction between oppositely charged ions
What is the primary reason for the accumulation of excess positive charges outside the cell membrane and excess negative charges inside the cell membrane?
The differential permeability of the membrane to different ions
Which of the following statements about the equilibrium potential for an ion species is correct?
The equilibrium potential is the potential at which the ion species is in dynamic equilibrium across the membrane
What is the primary function of the sodium-potassium pump (Na⁺/K⁺ ATPase) in maintaining the resting membrane potential?
To actively transport sodium ions out of the cell and potassium ions into the cell
How does myelination contribute to faster conduction velocity in axons?
It facilitates saltatory conduction where the action potential 'jumps' between nodes
What is the primary determinant of conduction velocity in unmyelinated axons?
The square root of the axon diameter
Which of the following statements about the resting membrane potential is correct?
It is typically around -70 mV in mammalian neurons
What would happen if a drug inhibited the postsynaptic potential of a sensory neuron?
It would decrease the likelihood of triggering an action potential in that neuron
What is the primary role of voltage-gated sodium (Na⁺) channels in generating an action potential?
They allow Na⁺ to flow into the cell, causing depolarization
What is the role of voltage-gated potassium (K⁺) channels in the action potential?
They allow K⁺ to flow out of the cell, causing repolarization
What is the role of hyperpolarization in the action potential?
It is the refractory period that prevents continuous firing
What is the primary function of the myelin sheath surrounding some axons?
To increase the speed of action potential propagation
Learn about the major classes of neurotransmitters and categories of cells in the nervous system. Explore the functions of neurons and neuroglia, the helper cells in the nervous system.
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