Question

Just as electrical wires have an outer coating axons are inserlated by a coating called the ________ ________.

Short answer

The coating that insulates axons is called the Myelin Sheath.

Step-by-step solution

Recall the basic structure of a neuron

There are three main parts in a typical neuron: the cell body or soma, the dendrites, and the axon. Here, focus is given to the axon, which is a long, slender projection that conducts electrical impulses away from the neuron's cell body.

Remember the insulating layer

Axons are insulated by a certain coating. This coating is made up of fat and protein, which prevents the electrical impulses from leaving the axon and increases the speed at which these impulses can travel.

Identify the term

Given these facts about the coating of the axon, recall that the insulating layer of the axon is called the myelin sheath.

Key concepts

Axon

The axon is a vital component of the neuron—a specialized cell in the nervous system. Axons are long, thin fibers that extend from the cell body of the neuron. Their primary job is to transmit electrical impulses from the nerve cell body to other neurons, muscles, or glands. Think of them as the highways of the nervous system.
To perform their function effectively, axons can range in length. Some are microscopic, while others stretch over a meter long, such as those found in the spinal cord leading to the toes.

• Though a neuron typically has one axon, it can branch off to communicate with multiple targets.
• Axon terminals are the endpoints where synapse connections to other cells occur.

Understanding the structure of an axon helps in recognizing how crucial they are for efficient signal transmission.

Myelin Sheath

The myelin sheath is like a protective coat for the axon, composed mostly of fatty substances and proteins. This layer insulates the axon, similar to the plastic coating around electrical wires. Its presence is fundamental in speeding up the transmission of electrical impulses. Without it, the signals would be much slower.
The formation of the myelin sheath occurs when glial cells wrap around the axon multiple times.

• In the central nervous system, the myelin sheath is formed by cells called oligodendrocytes.
• In the peripheral nervous system, Schwann cells are responsible for providing this insulation.

Additionally, the myelin sheath isn't a continuous layer. It has gaps known as nodes of Ranvier, which play an important role in rapid nerve impulse conduction, a process known as saltatory conduction.

Electrical Impulses

Electrical impulses, or action potentials, are the key form of communication within a neuron. These impulses are initiated when a neuron receives a signal from another neuron or from the environment via sensory inputs. Upon receiving a strong enough signal, an electrical charge travels down the axon.
The process works like this:

• Sodium and potassium ions flow across the axon membrane, creating a change in electrical charge.
• This change travels as a wave along the length of the axon.

Thanks to the myelin sheath, the electrical impulse jumps swiftly from one node of Ranvier to the next, enhancing speed and efficiency. This rapid transmission is crucial for quick reactions and smooth operation of the body's nervous system.