neuron has three basic parts: the dendrites, the cell body, and the axons. Some neurons have a fatty layer covering called around their axons. This layer isn’t continuous, and the gaps are called . The action potential jumps through these gaps to the transmission.
neuron has three basic parts: the dendrites, the cell body, and the axons. Some neurons have a fatty layer covering called around their axons. This layer isn’t continuous, and the gaps are called . The action potential jumps through these gaps to the transmission.
The Correct Answer and Explanation is:
Corrected version of the passage with answers filled in:
A neuron has three basic parts: the dendrites, the cell body, and the axons. Some neurons have a fatty layer covering called the myelin sheath around their axons. This layer isn’t continuous, and the gaps are called the nodes of Ranvier. The action potential jumps through these gaps to speed up transmission.
Explanation
Neurons are the fundamental units of the brain and nervous system, responsible for receiving sensory input, sending motor commands, and processing information. They are composed of three main parts: dendrites, cell body (soma), and axons. Dendrites are branched structures that receive signals from other neurons and transmit them toward the cell body. The cell body contains the nucleus and is essential for maintaining the neuron’s functions. The axon is a long, slender projection that transmits electrical impulses (action potentials) away from the cell body toward other neurons, muscles, or glands.
Many axons are covered by a fatty substance called the myelin sheath, which is produced by glial cells—Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system. The myelin sheath acts as an insulator, preventing the loss of electrical signals and increasing the speed of signal transmission along the axon.
However, the myelin sheath is not continuous. It has small gaps known as the nodes of Ranvier. These nodes are crucial for a process called saltatory conduction, where the action potential “jumps” from one node to the next rather than traveling continuously along the axon. This jumping mechanism allows for much faster signal propagation compared to unmyelinated axons.
The efficient transmission of electrical signals is essential for rapid communication between neurons, which underpins everything from reflexes to complex thought processes. Damage to the myelin sheath, such as in multiple sclerosis, can significantly impair nervous system function, leading to various neurological symptoms. Thus, the structural design of neurons, especially the presence of the myelin sheath and nodes of Ranvier, is key to the nervous system’s ability to operate quickly and effectively.
