Podcast
Questions and Answers
What is the primary role of kinesin in axonal transport?
What is the primary role of kinesin in axonal transport?
- Retrograde transport of toxins
- Retrograde transport of synaptic vesicles
- Anterograde transport using ATP (correct)
- Repairing damaged axons
Which type of axonal transport is primarily responsible for recycling and degrading axoplasmic substances?
Which type of axonal transport is primarily responsible for recycling and degrading axoplasmic substances?
- Anterograde transport
- Retrograde transport (correct)
- Slow transport
- Fast transport
What role do neurotubules play in axonal transport?
What role do neurotubules play in axonal transport?
- Fast anterograde transport
- Retrograde transport of viruses
- Retrograde transport
- Slow anterograde transport (correct)
How does saltatory conduction increase the velocity of nerve impulse transmission?
How does saltatory conduction increase the velocity of nerve impulse transmission?
What is the primary difference between myelinated and unmyelinated nerve fibers regarding nerve impulse conduction?
What is the primary difference between myelinated and unmyelinated nerve fibers regarding nerve impulse conduction?
In a neuron at rest, where are sodium ions (Na+) more concentrated?
In a neuron at rest, where are sodium ions (Na+) more concentrated?
During the wave of repolarization: what is the relative movement of $Na^+$ and $K^+$ ions?
During the wave of repolarization: what is the relative movement of $Na^+$ and $K^+$ ions?
How does the refractory period contribute to the unidirectional propagation of an action potential?
How does the refractory period contribute to the unidirectional propagation of an action potential?
What is the significance of the initial segment of the axon in nerve impulse transmission?
What is the significance of the initial segment of the axon in nerve impulse transmission?
What triggers the opening of voltage-gated $K^+$ channels during an action potential?
What triggers the opening of voltage-gated $K^+$ channels during an action potential?
Apart from synaptic vesicles, which of the following are transported via fast anterograde transport?
Apart from synaptic vesicles, which of the following are transported via fast anterograde transport?
In which direction does retrograde axonal transport move materials?
In which direction does retrograde axonal transport move materials?
What property of neurons allows them to respond to stimuli and transmit signals?
What property of neurons allows them to respond to stimuli and transmit signals?
What physiological process affects the neuron's ability to generate an electrical signal?
What physiological process affects the neuron's ability to generate an electrical signal?
How do myelinated nerves achieve fast conduction velocity?
How do myelinated nerves achieve fast conduction velocity?
In a neuron at rest, where are potassium ions ($K^+$) primarily concentrated?
In a neuron at rest, where are potassium ions ($K^+$) primarily concentrated?
What is the main consequence of Na+ ions rushing into the axon during the initial phase of an action potential?
What is the main consequence of Na+ ions rushing into the axon during the initial phase of an action potential?
What happens immediately after depolarization in an unmyelinated nerve fiber?
What happens immediately after depolarization in an unmyelinated nerve fiber?
Which event directly contributes to the repolarization phase of an action potential?
Which event directly contributes to the repolarization phase of an action potential?
Flashcards
Axonal transport
Axonal transport
Movement of materials through the axon.
Anterograde transport
Anterograde transport
Moves materials away from the cell body; uses kinesin.
Retrograde transport
Retrograde transport
Moves materials towards the cell body; uses dynein.
Fast axonal transport
Fast axonal transport
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Slow axonal transport
Slow axonal transport
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Irritability (Excitability)
Irritability (Excitability)
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Conductivity
Conductivity
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Myelinated nerves
Myelinated nerves
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Unmyelinated nerves
Unmyelinated nerves
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Saltatory Conduction
Saltatory Conduction
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Extracellular ion concentrations
Extracellular ion concentrations
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Intracellular ion concentrations
Intracellular ion concentrations
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Graded potentials
Graded potentials
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Action Potential
Action Potential
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Following a threshold stimulus
Following a threshold stimulus
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Repolarization
Repolarization
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Depolarization
Depolarization
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Hyperpolarization
Hyperpolarization
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Nerve Impulse
Nerve Impulse
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Myelin Sheath
Myelin Sheath
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Study Notes
Axonal Transport
- Axonal transport involves the movement of materials through the axon
- Anterograde transport uses the "MAP" kinesin with ATP
- Retrograde transport uses "MAP" dynein.
Fast Axonal Transport
- Fast transport occurs at a rate of 2 to 40 cm/day.
- It moves organelles such as synaptic vesicles, SER, and mitochondria.
- It transports acetylcholinesterase, axolemma components, glucose, amino acids, nucleotides, and calcium in an anterograde manner.
- Synaptic vesicles and axoplasmic substances are transported in a retrograde manner for recycling and degradation
- Viruses and toxins move towards the soma via retrograde transport
Slow Axonal Transport
- Slow transport occurs at a rate of 0.2 to 4 mm/day.
- It transports enzymes, cytoskeletal proteins, and cytoplasmic proteins
- This process involves neurotubules in an anterograde manner.
- It repairs and regenerates damaged axon tips
- Slow axonal transport is poorly understood
Neuron Properties
- Neurons exhibit irritability (excitability) and conductivity.
- Nerves can be unmyelinated, resulting in slow conduction velocity
- Nerves can be myelinated, resulting in fast conduction velocity due to saltatory conduction
- Key physiological processes include intracellular transport, membrane potential levels, and ion fluxes for Na+, K+, and Cl-.
Neuronal Function
- Neuronal functions arise from irritability and conductivity.
- Myelinated nerves utilize saltatory conduction
- Unmyelinated nerves utilize continuous conduction
- Membrane potentials and ion fluxes of Na+, K+, and Cl- dictate neuronal function
Ion Concentrations
- Sodium (Na+) and chloride (Cl-) have high concentrations outside the axon
- Potassium (K+) and negatively charged proteins have high concentrations inside the axon
- Extracellular concentrations: Na+ at 150, K+ at 5, Cl- at 110
- Intracellular concentrations: Na+ at 15, K+ at 150, Cl- at 10
Resting membrane potential
- The membrane potential when a neuron is at rest
Excitatory postsynaptic potential (EPSP)
- A postsynaptic potential that makes the postsynaptic neuron more likely to fire an action potential
Inhibitory postsynaptic potential (IPSP)
- A postsynaptic potential that makes the postsynaptic neuron less likely to fire an action potential
Threshold stimulus
- Following a threshold stimulus, Na+ ions rush into the initial segment of the axon, which has low electrical resistance.
Depolarization
- Na+ ions enter voltage-gated channels, causing depolarization to continue down the axon.
Repolarization
- As Na+ ions flood in, K+ voltage-gated channels open, initiating repolarization after depolarization.
Action Potential Propagation
- The process of depolarization and repolarization repeats until the action potential propagation sequence is completed in milliseconds.
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