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Questions and Answers
What initiates the release of neurotransmitters at the nerve ending?
What initiates the release of neurotransmitters at the nerve ending?
- Action potential arrival (correct)
- Influx of sodium ions
- Influx of potassium ions
- Calcium ions leaving the presynaptic terminal
Which neurotransmitter is exclusively used at all skeletal neuromuscular junctions?
Which neurotransmitter is exclusively used at all skeletal neuromuscular junctions?
- Acetylcholine (correct)
- Norepinephrine
- Serotonin
- Dopamine
What determines whether an action potential will be generated in the postsynaptic neuron?
What determines whether an action potential will be generated in the postsynaptic neuron?
- The type of neurotransmitter released
- The number of neurotransmitters released
- The summation of postsynaptic responses (correct)
- The distance between the synapses
What occurs after neurotransmitters are ejected into the extracellular fluid in the synaptic cleft?
What occurs after neurotransmitters are ejected into the extracellular fluid in the synaptic cleft?
Which of the following is not a neurotransmitter mentioned?
Which of the following is not a neurotransmitter mentioned?
What is true about slow axonal transport?
What is true about slow axonal transport?
What initiates an action potential in a neuron?
What initiates an action potential in a neuron?
How long does an action potential last?
How long does an action potential last?
What is the primary characteristic of an action potential during its propagation?
What is the primary characteristic of an action potential during its propagation?
What is the function of the refractory period in nerve impulses?
What is the function of the refractory period in nerve impulses?
What happens to the strength of depolarization with increasing stimulus strength?
What happens to the strength of depolarization with increasing stimulus strength?
How do sodium and potassium channels contribute to neuron function?
How do sodium and potassium channels contribute to neuron function?
Which of the following describes summation in neuronal excitation?
Which of the following describes summation in neuronal excitation?
Which type of neuron has a single neurite that divides shortly from the cell body?
Which type of neuron has a single neurite that divides shortly from the cell body?
What is a defining feature of Golgi Type 1 neurons?
What is a defining feature of Golgi Type 1 neurons?
Where are bipolar neurons typically found?
Where are bipolar neurons typically found?
Which arrangement of neurites is characteristic of multipolar neurons?
Which arrangement of neurites is characteristic of multipolar neurons?
Which of the following best describes the location of unipolar neurons?
Which of the following best describes the location of unipolar neurons?
What is a primary function of neuroglial cells in relation to neurons?
What is a primary function of neuroglial cells in relation to neurons?
What distinguishes bipolar neurons from unipolar neurons?
What distinguishes bipolar neurons from unipolar neurons?
What is the primary highlight of the classification of neurons based on their morphology?
What is the primary highlight of the classification of neurons based on their morphology?
What is the primary role of kinesin in neuronal transport?
What is the primary role of kinesin in neuronal transport?
Which statement accurately distinguishes between rapid and slow transport in neurons?
Which statement accurately distinguishes between rapid and slow transport in neurons?
What determines the direction and speed of organelle movement in neurons?
What determines the direction and speed of organelle movement in neurons?
Which of the following is NOT a feature of slow transport?
Which of the following is NOT a feature of slow transport?
What are the motor proteins involved in rapid transport and their respective functions?
What are the motor proteins involved in rapid transport and their respective functions?
How are the movements of organelles in neurons characterized in terms of their speed?
How are the movements of organelles in neurons characterized in terms of their speed?
Which characteristic defines the function of dynein within neurons?
Which characteristic defines the function of dynein within neurons?
What is a key difference between the roles of kinesin and dynein in neuronal function?
What is a key difference between the roles of kinesin and dynein in neuronal function?
What is the primary function of dendrites in a nerve cell?
What is the primary function of dendrites in a nerve cell?
Which process involves the fast anterograde transport?
Which process involves the fast anterograde transport?
What is a characteristic of slow anterograde transport?
What is a characteristic of slow anterograde transport?
Which structures are specifically referred to as dendritic spines?
Which structures are specifically referred to as dendritic spines?
How do microtubules assist in axon transport?
How do microtubules assist in axon transport?
What is the typical rate of slow anterograde transport?
What is the typical rate of slow anterograde transport?
What role do dendrites play in the nerve cell?
What role do dendrites play in the nerve cell?
Which statement best describes axon transport in nerve cells?
Which statement best describes axon transport in nerve cells?
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Study Notes
Classification of Neurons
- Neurons are classified based on morphology, arrangement of neurites, and location within the nervous system.
- Types include:
- Unipolar: Single neurite, found in the posterior root ganglion, dividing shortly from the cell body.
- Bipolar: Single neurite from either end of the cell body, located in the retina and sensory ganglia.
- Multipolar: Many dendrites and one long axon, found in brain fiber tracts, spinal cord, and peripheral nerves.
Structure and Function of Neurons
- Neurons facilitate communication within the nervous system through electrical impulses.
- Axon transport occurs via microtubules aided by microfilaments.
- Fast anterograde transport: 100-400 mm/day, moving proteins and neurotransmitters.
- Slow anterograde transport: 0.1-3.0 mm/day, moving axoplasm and organelles.
Plasma Membrane and Action Potential
- The cell membrane's excitation leads to depolarization caused by Na+ ions entering the cytoplasm.
- The action potential is a brief electrical signal lasting approximately 5 msec.
- It propagates along neurites, maintaining size and frequency, while undergoing a refractory period where subsequent action potentials cannot occur immediately.
Ion Channels and Stimuli
- Sodium (Na+) and potassium (K+) channels are crucial for generating action potentials.
- Initial depolarization depends on the strength of stimuli, allowing summation of multiple excitatory signals.
- Subthreshold stimuli can influence neuron activity without triggering full depolarization.
Neuron Processes
- Neurites consist of dendrites and axons.
- Dendrites are short, extending from the cell body to receive signals from other neurons and conduct impulses toward the cell body.
- Dendritic spines increase the surface area for synaptic connections.
Chemical Synapses
- Neurotransmitters are released across synaptic clefts, attaching to receptors on the postsynaptic membrane.
- Examples include acetylcholine, norepinephrine, dopamine, and serotonin.
- The process involves:
- Action potential arrival leading to calcium influx.
- Synaptic vesicles fuse with the presynaptic membrane, releasing neurotransmitters into the extracellular fluid.
- The effect on the postsynaptic neuron depends on the summation of responses at various synapses, potentially initiating an action potential.
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