40 Questions
What is the location where myelin is produced in the Central Nervous System (CNS)?
Oligodendrocytes
What is the primary function of the myelin sheath in the Central Nervous System (CNS)?
To increase the speed of impulse conduction along the axon
What is the name given to the small gaps in the myelin sheath where myelin is absent?
Nodes of Ranvier
What is the relationship between axonal diameter and the velocity of propagation of action potentials?
The thicker the axon, the faster the conduction velocity
What is the characteristic of the distribution of voltage-sensitive Na+ and K+ channels in unmyelinated nerve fibers?
They are distributed uniformly along the axon
In myelinated nerve fibers, where are voltage-sensitive Na+ channels clustered in high density?
At the nodes of Ranvier
What is the characteristic of the propagation of action potentials in unmyelinated nerve fibers?
It occurs in a continuous manner
What is the effect of the myelin sheath on the conduction velocity of nerve impulses?
It increases the conduction velocity
What is the function of the axon hillock in a neuron?
Initiates action potential and transmits it to the axon
What is the direction of anterograde axonal transport?
From the soma down the axon toward the presynaptic terminal
What is the function of the dendrites in a neuron?
Receive information from other cells
What is the purpose of retrograde axonal transport?
To move substances from the synapse back to the soma
What is the function of the soma in a neuron?
Synthesizes proteins used as neurotransmitters
Where is the myelin sheath produced in the Peripheral Nervous System (PNS)?
By Schwann cells
What is the primary function of the axon in a neuron?
Sends information to other neurons or muscle cells
What is the length range of axons?
Less than 1 mm to up to 1 meter in length
What is the primary location of K+ channels in myelinated axons?
In the internodal area
What is the term for the conduction of action potential in myelinated axons?
Saltatory conduction
What is the percentage of axodendritic synapses in the nervous system?
80-95%
What is the function of axoaxonic synapses?
Modulate transmitter release
What is the term for the transmission of information between neurons?
Synaptic transmission
Which type of synapse is common in invertebrates?
Electrical synapse
What is the term for the region where the axon terminal of one neuron meets the dendrite of another neuron?
Synaptic junction
What is the term for the point of functional contact between axons and skeletal muscle?
Neuromuscular junction
What is the primary mechanism of transmission at an electrical synapse?
Flow of ions through gap junctions
What is the main function of synaptic vesicles?
To store and release neurotransmitters
What triggers the release of neurotransmitters into the synaptic cleft?
The influx of Ca2+ ions through voltage-gated channels
What is the role of the post-synaptic neuron in chemical transmission?
To bind neurotransmitters to receptors
What is the direction of transmission at a chemical synapse?
Unidirectional
What is the space between two neurons that serves as the site for intraneuronal communication?
Synaptic cleft
What is the process by which neurotransmitters are released from the presynaptic terminal?
Exocytosis
What is the primary component of the synapse that receives the signal?
Post-synaptic neuron
What is the primary effect of conformational changes in agent-specific postsynaptic receptors in the narrow synaptic cleft?
Opening or closing of ion channels
What is the primary mechanism by which myasthenia gravis affects neurotransmission at the neuromuscular junction?
Antibodies attack the acetylcholine receptor in the postjunctional folds
What is the characteristic pattern of muscle weakness and fatigability in myasthenia gravis?
Variable in severity and progressive throughout the day
What is the primary effect of acetylcholinesterase inhibitors in myasthenia gravis?
Increasing the efficacy of acetylcholine in the neuromuscular cleft
What is the primary difference between myasthenia gravis and Lambert-Eaton syndrome?
_site of action of the autoimmune response
What is the effect of repetitive stimulation on muscle action potentials in myasthenia gravis?
Progressive decrease in muscle action potentials
What is the characteristic feature of the postjunctional folds in myasthenia gravis?
Decreased localization of acetylcholine receptors
What is the primary effect of the autoimmune response in Lambert-Eaton syndrome?
Reducing the release of acetylcholine from the nerve terminal
This quiz covers the definition, structure, and process of synaptic transmission, as well as diseases related to synaptic transmission. It also explores the components of neurons, including the soma, dendrites, axon, and presynaptic terminals.
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