Podcast
Questions and Answers
What allows the central nervous system (CNS) to distinguish between a weak stimulus and a strong stimulus?
What allows the central nervous system (CNS) to distinguish between a weak stimulus and a strong stimulus?
- The frequency of impulses generated (correct)
- The amplitude of the action potential
- The duration of the action potential
- The speed of the nerve impulse
What is the primary reason that saltatory conduction increases the speed of nerve impulses?
What is the primary reason that saltatory conduction increases the speed of nerve impulses?
- The diameter of the nerve fibers decreases
- Action potentials have a higher amplitude in myelinated fibers
- Impulse conduction occurs continuously along the axon
- Myelinated nerves allow impulses to jump between nodes (correct)
During which phase is the membrane potential at its peak, indicating an action potential?
During which phase is the membrane potential at its peak, indicating an action potential?
- Repolarization phase
- Resting potential phase
- Hyperpolarization phase
- Action potential peak phase (correct)
How does the conduction speed of nerve impulses vary with the diameter of the nerve fibers?
How does the conduction speed of nerve impulses vary with the diameter of the nerve fibers?
What happens to the membrane at the recording electrode after the action potential peak?
What happens to the membrane at the recording electrode after the action potential peak?
What is the primary role of sensory input in the nervous system?
What is the primary role of sensory input in the nervous system?
Which of the following accurately describes the Central Nervous System (CNS)?
Which of the following accurately describes the Central Nervous System (CNS)?
What distinguishes the somatic nervous system from the autonomic nervous system?
What distinguishes the somatic nervous system from the autonomic nervous system?
What characterizes the sympathetic division of the autonomic nervous system?
What characterizes the sympathetic division of the autonomic nervous system?
Which statement regarding neurons is accurate?
Which statement regarding neurons is accurate?
What is the function of myelin in the nervous system?
What is the function of myelin in the nervous system?
Which of the following correctly pairs a division of the Peripheral Nervous System with its function?
Which of the following correctly pairs a division of the Peripheral Nervous System with its function?
What is the role of Schwann cells in the nervous system?
What is the role of Schwann cells in the nervous system?
Which of the following structures contains vesicles with neurotransmitters?
Which of the following structures contains vesicles with neurotransmitters?
Which division of the autonomic nervous system promotes housekeeping functions during rest?
Which division of the autonomic nervous system promotes housekeeping functions during rest?
What is the primary effect of neurotransmitter binding on the postsynaptic membrane?
What is the primary effect of neurotransmitter binding on the postsynaptic membrane?
Which process does NOT terminate neurotransmitter effects?
Which process does NOT terminate neurotransmitter effects?
What ion movement occurs during an excitatory postsynaptic potential (EPSP)?
What ion movement occurs during an excitatory postsynaptic potential (EPSP)?
What term describes the local depolarization of the postsynaptic membrane?
What term describes the local depolarization of the postsynaptic membrane?
During neurotransmitter action, what happens to the membrane potential?
During neurotransmitter action, what happens to the membrane potential?
What role does cAMP play in cellular processes?
What role does cAMP play in cellular processes?
Which process is initiated by G-protein linked receptors?
Which process is initiated by G-protein linked receptors?
What is a common symptom of Multiple Sclerosis?
What is a common symptom of Multiple Sclerosis?
What is one treatment option mentioned for Multiple Sclerosis?
What is one treatment option mentioned for Multiple Sclerosis?
What causes the symptoms of Multiple Sclerosis?
What causes the symptoms of Multiple Sclerosis?
What is the primary function of myelin sheaths in neurons?
What is the primary function of myelin sheaths in neurons?
What term describes the type of conduction that occurs in myelinated axons?
What term describes the type of conduction that occurs in myelinated axons?
Which group of nerve fibers has the largest diameter and is myelinated?
Which group of nerve fibers has the largest diameter and is myelinated?
In a chemical synapse, which process allows neurotransmitters to be released into the synaptic cleft?
In a chemical synapse, which process allows neurotransmitters to be released into the synaptic cleft?
Which type of synapse involves the cell body of the postsynaptic neuron receiving impulses?
Which type of synapse involves the cell body of the postsynaptic neuron receiving impulses?
What role do voltage-gated Ca2+ channels play in synaptic transmission?
What role do voltage-gated Ca2+ channels play in synaptic transmission?
Which characteristic distinguishes Group C fibers from other fiber types?
Which characteristic distinguishes Group C fibers from other fiber types?
What is the role of the presynaptic neuron in a synapse?
What is the role of the presynaptic neuron in a synapse?
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Study Notes
Nervous System Overview
- Comprises the Central Nervous System (CNS) and Peripheral Nervous System (PNS).
- Functions: sensory input, integration, and motor output.
Structure and Classification
- Central Nervous System (CNS): Includes the brain and spinal cord; acts as integrative and control center.
- Peripheral Nervous System (PNS): Made up of cranial and spinal nerves; serves as communication lines between CNS and body.
PNS Divisions
- Sensory Division: Transmits impulses from receptors to the CNS.
- Motor Division: Conducts impulses from CNS to effectors (muscles and glands).
- Somatic Nervous System: Voluntary control over skeletal muscles.
- Autonomic Nervous System (ANS): Involuntary control over smooth muscles, cardiac muscles, and glands.
- Sympathetic Division: Mobilizes body systems during activity.
- Parasympathetic Division: Conserves energy and promotes housekeeping functions during rest.
Neurons
- Basic units of the nervous system; long-lived and do not undergo mitosis.
- Composed of a cell body, dendrites, axons, and axonal terminals containing neurotransmitters.
- Synapse: Gap between axonal terminals and target neurons, transmitting signals.
Nerve Coverings and Impulse Conduction
- Myelin: Lipid/protein covering of axons that increases impulse speed.
- Schwann Cells: Form myelin in the PNS and contain nodes of Ranvier, which facilitate faster conduction (saltatory conduction).
- Impulse speed is faster in myelinated nerves and increases with axon diameter.
Action Potential and Coding for Intensity
- All action potentials are identical; CNS differentiates stimulus intensity by the frequency of action potentials.
- Stronger stimuli produce higher frequency action potentials, leading to a stronger signal.
Nerve Fiber Classification
- Group A Fibers: Largest diameter, myelinated fibers for somatic sensory and motor functions.
- Group B Fibers: Intermediate diameter, lightly myelinated ANS fibers.
- Group C Fibers: Smallest diameter, unmyelinated ANS fibers.
Synapses
- Presynaptic Neuron: Sends impulses toward the synapse.
- Postsynaptic Neuron: Receives impulses from the synapse.
- Types include axodendritic, axosomatic, and axoaxonic synapses.
- Chemical synapses use neurotransmitters to transmit signals.
Neurotransmitter Mechanism
- Action potential arrival causes opening of voltage-gated calcium channels.
- Calcium influx triggers neurotransmitter release from synaptic vesicles via exocytosis.
- Neurotransmitters bind to receptors on the postsynaptic membrane, resulting in graded potentials.
- Neurotransmitter effects can be terminated by reuptake, enzymatic degradation, or diffusion.
Membrane Potential
- Excitatory Post-Synaptic Potentials (EPSP) bring neurons closer to action potential threshold through Na+ and K+ ion movement.
- G-protein linked receptors activate second messengers like cyclic AMP, influencing cellular responses.
Clinical Application: Multiple Sclerosis
- Symptoms include blurred vision and numbness, potentially leading to paralysis.
- Caused by destruction of myelin in the CNS, leading to impaired nerve impulse conduction.
- Treatments involve no cure, but options like bone marrow transplants, interferons, and hormones are available.
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