A Node of Ranvier (Myelin Sheath Gap)

question 44

Multiple Choice

A node of Ranvier (myelin sheath gap)

• A) is one segment of the myelin sheath.
• B) occurs in the PNS but not in the CNS.
• C) is a bare region of axonal membrane in myelinated axons only.
• D) occurs only in ganglia.

---

Definitions:

Neurotransmitter

Chemical messengers that transmit signals across synapses from one neuron to another, facilitating communication within the nervous system.

Voluntary Muscles

Muscles that can be consciously controlled to perform movements, as opposed to involuntary muscles, such as those in the heart or digestive system.

Agonist

An agonist is a chemical or drug that binds to receptors in the brain and activates them, often mimicking the action of naturally occurring substances.

GABA

Gamma-Aminobutyric Acid, a chief inhibitory neurotransmitter in the mammalian central nervous system, playing a key role in reducing neuronal excitability.