Neuroscience Quiz: Action Potentials

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Questions and Answers

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?

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?

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?

Speed increases with increased diameter Signup and view all the answers

What happens to the membrane at the recording electrode after the action potential peak?

The membrane enters a phase of hyperpolarization Signup and view all the answers

What is the primary role of sensory input in the nervous system?

To conduct impulses from receptors to the CNS Signup and view all the answers

Which of the following accurately describes the Central Nervous System (CNS)?

Functions as integrative and control centers Signup and view all the answers

What distinguishes the somatic nervous system from the autonomic nervous system?

Somatic controls voluntary muscle movement, while autonomic controls involuntary functions Signup and view all the answers

What characterizes the sympathetic division of the autonomic nervous system?

Mobilizes body systems during activity Signup and view all the answers

Which statement regarding neurons is accurate?

Neurons are long-lived and do not undergo mitosis Signup and view all the answers

What is the function of myelin in the nervous system?

To increase the speed of nerve impulse conduction Signup and view all the answers

Which of the following correctly pairs a division of the Peripheral Nervous System with its function?

Visceral Sensory Division - conducts impulses from receptors to the CNS Signup and view all the answers

What is the role of Schwann cells in the nervous system?

To form the myelin sheath around axons Signup and view all the answers

Which of the following structures contains vesicles with neurotransmitters?

Axonal terminals Signup and view all the answers

Which division of the autonomic nervous system promotes housekeeping functions during rest?

Parasympathetic division Signup and view all the answers

What is the primary effect of neurotransmitter binding on the postsynaptic membrane?

Opens chemically gated ion channels Signup and view all the answers

Which process does NOT terminate neurotransmitter effects?

Increased ion channel activity Signup and view all the answers

What ion movement occurs during an excitatory postsynaptic potential (EPSP)?

Both Na+ and K+ ions pass simultaneously Signup and view all the answers

What term describes the local depolarization of the postsynaptic membrane?

Graded potential Signup and view all the answers

During neurotransmitter action, what happens to the membrane potential?

Excitatory signals lead to depolarization Signup and view all the answers

What role does cAMP play in cellular processes?

It activates specific genes. Signup and view all the answers

Which process is initiated by G-protein linked receptors?

Conversion of ATP to cAMP. Signup and view all the answers

What is a common symptom of Multiple Sclerosis?

Blurred vision. Signup and view all the answers

What is one treatment option mentioned for Multiple Sclerosis?

Bone marrow transplant. Signup and view all the answers

What causes the symptoms of Multiple Sclerosis?

Destruction of myelin in the CNS. Signup and view all the answers

What is the primary function of myelin sheaths in neurons?

To insulate and prevent charge leakage Signup and view all the answers

What term describes the type of conduction that occurs in myelinated axons?

Saltatory conduction Signup and view all the answers

Which group of nerve fibers has the largest diameter and is myelinated?

Group A fibers Signup and view all the answers

In a chemical synapse, which process allows neurotransmitters to be released into the synaptic cleft?

Exocytosis Signup and view all the answers

Which type of synapse involves the cell body of the postsynaptic neuron receiving impulses?

Axosomatic synapse Signup and view all the answers

What role do voltage-gated Ca2+ channels play in synaptic transmission?

They allow calcium ions to enter the axon terminal Signup and view all the answers

Which characteristic distinguishes Group C fibers from other fiber types?

They are unmyelinated and have the smallest diameter Signup and view all the answers

What is the role of the presynaptic neuron in a synapse?

To release neurotransmitters into the synaptic cleft Signup and view all the answers

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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Description

Test your understanding of action potentials and the central nervous system's mechanisms. This quiz covers topics such as stimulus strength, saltatory conduction, membrane potential, and conduction speed in nerve fibers. Dive into the fascinating world of neuroscience and assess your knowledge!