Question

Non-myelinating Schwann cell is characterized by the following properties EXCEPT a. Wraps axons greater than \(1 \mu \mathrm{m}\). b. Appear later than myelinating Schwann cells. c. Myelinate all post-ganglionic sympathetic neurons. d. Produce more p75NTR and GFAP. e. Provide mechanical and metabolic support to the neuron.

Short answer

a. Wraps axons greater than \(1 \mu \mathrm{m}\). b. Appear later than myelinating Schwann cells. c. Myelinate all post-ganglionic sympathetic neurons. d. Produce more p75NTR and GFAP. e. Provide mechanical and metabolic support to the neuron. Answer: c. Myelinate all post-ganglionic sympathetic neurons.

Step-by-step solution

Understand the properties of non-myelinating Schwann cells

Non-myelinating Schwann cells are a type of glial cell that plays an important role in supporting nerve cells. These cells do not wrap around the nerve cells (axons) to create a myelin sheath, but instead, they provide support, guidance, and maintenance of the nerve cells.

Compare the given options with the properties of non-myelinating Schwann cells

Let's analyze each option and compare it to what we know about non-myelinating Schwann cells: a. Wraps axons greater than \(1 \mu \mathrm{m}\). Non-myelinating Schwann cells do not wrap around axons to form a myelin sheath, so this option is incorrect. b. Appear later than myelinating Schwann cells. Non-myelinating Schwann cells do develop later than myelinating Schwann cells in the nervous system, so this option is consistent with their properties. c. Myelinate all post-ganglionic sympathetic neurons. Since non-myelinating Schwann cells do not create a myelin sheath, they cannot myelinate any neurons, including post-ganglionic sympathetic neurons. This option is incorrect. d. Produce more p75NTR and GFAP. Non-myelinating Schwann cells do produce more p75NTR (a neurotrophin receptor) and GFAP (glial fibrillary acidic protein) than myelinating Schwann cells. These proteins are involved in the maintenance and functioning of non-myelinating Schwann cells, so this option is consistent with their properties. e. Provide mechanical and metabolic support to the neuron. Non-myelinating Schwann cells are essential for providing mechanical and metabolic support to neurons, as they maintain the structure and health of nerve cells. This option is consistent with their properties.

Identify the option that does NOT characterize non-myelinating Schwann cells

After comparing the given options with the properties of non-myelinating Schwann cells, we find that options a and c do NOT characterize non-myelinating Schwann cells, as they do not wrap around axons to create a myelin sheath and are unable to myelinate neurons. However, since we are supposed to choose only one answer, we should choose the one that makes the least sense for non-myelinating Schwann cells: The correct answer is c: Myelinate all post-ganglionic sympathetic neurons. This is the least accurate characteristic of non-myelinating Schwann cells, as they do not myelinate any neurons.

Key concepts

Neuroscience

Neuroscience is the scientific study of the nervous system, a complex network that includes the brain, spinal cord, and a vast network of nerves that traverse the entire body. Special cells called neurons are responsible for transmitting and receiving electrical signals, allowing us to think, feel, and move.

Understanding the intricate dance of cellular activities involved in nerve function is key to unraveling the mysteries of the brain and developing treatments for neurological disorders. It encapsulates the molecular biology, anatomy, function, and evolution of neurons and neural networks, and also incorporates findings from psychology, computer science, and other disciplines to build a comprehensive picture of how the nervous system operates.

Glial Cells

Glial cells, often referred to as the 'supporting cells' of the nervous system, serve various crucial roles which are just as important as those played by neurons. They are not involved in the electrical signaling pathways like neurons, but they maintain homeostasis, form myelin, and provide support and protection for neurons. There are several types of glial cells, with each having distinct functions.

For example, astrocytes maintain the blood-brain barrier, microglia act as the immune defense of the central nervous system, oligodendrocytes myelinate neurons in the central nervous system, and Schwann cells myelinate the neurons in the peripheral nervous system.

Neuron Support

Schwann cells are the principal glia of the peripheral nervous system and come in two main types: myelinating and non-myelinating. Both types are pivotal in neuron support. Myelinating Schwann cells insulate nerve fibers to speed up electrical signal transmission, while non-myelinating Schwann cells support multiple axons by enveloping them and ensuring their survival and function. Beyond structural support, Schwann cells influence neuron repair after injury, engage in the removal of cellular debris, and regulate the microenvironment of peripheral nerves. Such support is vital for the overall functioning and maintenance of the nervous system.

Myelin Sheath

The myelin sheath is a fatty insulating layer that surrounds the axon of many neurons. Produced by oligodendrocytes in the central nervous system and by Schwann cells in the peripheral nervous system, myelin is essential for efficient transmission of electrical impulses along the nerve cell. It's analogous to the insulation around electrical wires, preventing signal loss and allowing for faster signal transmission. The gaps between sections of myelin sheath, known as Nodes of Ranvier, allow for the 'jumping' of the action potential along the axon, further speeding up neural communication. Without the myelin sheath, neural communication would be significantly slower and could be disrupted, leading to diseases such as Multiple Sclerosis, where demyelination occurs.