Central Nervous System Myelinated Axon Structure

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Which type of nerve fibers have the fastest conduction velocity?

A fibers (correct)

Delta fibers

B fibers

C fibers

Which type of fibers are responsible for sharp pain?

Beta (β) fibers

Alpha (α) fibers

Delta (δ) fibers (correct)

Gamma (γ) fibers

What is the main characteristic of nonmyelinated nerves?

They have a myelin sheath

They are the largest nerve fibers

They are primarily motor fibers

They have high-electrical resistance cell membranes (correct)

What is the primary function of Beta (β) fibers?

Awareness of position/equilibrium Signup and view all the answers

Which type of nerve fibers are the most numerous fiber type in the Peripheral Nervous System (PNS)?

C fibers Signup and view all the answers

What is a characteristic feature of A-Delta fibers?

They are myelinated Signup and view all the answers

What type of fibers are primarily responsible for sharp dental pain?

A-delta fibers Signup and view all the answers

Which type of fibers are the most numerous and usually unmyelinated?

C fibers Signup and view all the answers

Which type of fibers are lightly myelinated motor fibers?

A fibers Signup and view all the answers

In the oral cavity, which type of fibers are found abundantly?

A-delta fibers Signup and view all the answers

What principle ensures that the nerve impulse will travel the length of the nerve fiber at its initial strength?

All-or-none firing principle Signup and view all the answers

Why do A-delta fibers require more anesthetic volume for complete nerve blockage?

They are larger in size and myelinated Signup and view all the answers

What happens during the process of depolarization?

The cell becomes more positively charged inside and more negatively charged outside. Signup and view all the answers

What is the role of ion-gated channels during depolarization?

They open to allow more sodium ions to enter the cell. Signup and view all the answers

What is the average electric potential at which an action potential is created?

15-20 mV Signup and view all the answers

What is the role of neurotransmitters in the transmission of signals between neurons?

Neurotransmitters are released from the presynaptic cell and bind to receptors on the postsynaptic cell, transmitting the signal. Signup and view all the answers

How do local anesthetics work as sodium channel blockers?

Local anesthetics bind to the sodium channels, causing them to close and prevent sodium ions from entering the nerve. Signup and view all the answers

What is the difference between excitatory and inhibitory neurotransmitters?

Excitatory neurotransmitters increase the likelihood of an action potential, while inhibitory neurotransmitters decrease it. Signup and view all the answers

Which of the following is responsible for forming the myelin sheath around axons in the central nervous system (CNS)?

Oligodendrocytes Signup and view all the answers

What is the function of the Nodes of Ranvier along myelinated axons?

To facilitate saltatory conduction of action potentials Signup and view all the answers

Which of the following statements about nerve regeneration is correct?

Myelinated axons in the peripheral nervous system (PNS) can regenerate, but unmyelinated axons cannot. Signup and view all the answers

Which of the following best describes saltatory conduction?

The rapid propagation of action potentials from one Node of Ranvier to the next along myelinated axons Signup and view all the answers

What is the primary cause of the neurological symptoms in multiple sclerosis?

Demyelination of axons in the central nervous system Signup and view all the answers

Which of the following statements about nerve regeneration in the central nervous system (CNS) is correct?

Neither myelinated nor unmyelinated axons in the CNS can regenerate Signup and view all the answers

What is the primary mode of action of local anesthetics?

Inhibiting sodium influx through voltage-gated sodium channels in the neuronal cell membrane Signup and view all the answers

Which type of nerve fibers are more sensitive to local anesthetics?

Both small myelinated and non-myelinated axons Signup and view all the answers

Why do larger nerve fibers require more time for the local anesthetic to take effect?

More nodes of Ranvier need to be blocked for complete conduction block Signup and view all the answers

What happens when local anesthetics are administered?

Depolarization of the nerve membrane is prevented Signup and view all the answers

Which order do local anesthetics block nerve fiber conduction?

Small myelinated axons, non-myelinated axons, large myelinated axons Signup and view all the answers

What is the significance of the nodes of Ranvier in the action of local anesthetics?

They are the sites where local anesthetics bind to sodium channels Signup and view all the answers