Chapter 12 - Section 12.3 - Study Guide - Assess Your Learning Outcomes - Page 471: 1

Neuroglia, also known as glial cells, are non-neuronal cells in the nervous system that provide various supportive functions for neurons. There are several types of neuroglia, and they can be categorized into two main groups based on their location within the nervous system: those found in the central nervous system (CNS) and those found in the peripheral nervous system (PNS). Here are six types of neuroglia, their structures, functions, and their distribution in the CNS and PNS: **In the Central Nervous System (CNS):** 1. **Astrocytes:** - **Structure:** Astrocytes have numerous branching processes that radiate from a central cell body. They often have star-shaped appearances. - **Functions:** Astrocytes provide structural support to neurons, help regulate the extracellular environment by maintaining ion balance, and form the blood-brain barrier, which restricts the passage of substances from the bloodstream into the brain. They also play a role in synaptic signaling and the repair of neural tissue. 2. **Microglia:** - **Structure:** Microglia are small, highly motile cells with multiple branching processes. - **Functions:** Microglia are the resident immune cells of the CNS. They monitor the brain for pathogens, damaged cells, and debris. When activated, they function as phagocytes, engulfing and removing foreign invaders and cellular debris. 3. **Oligodendrocytes:** - **Structure:** Oligodendrocytes have a round or oval cell body with multiple extensions, each of which can wrap around and insulate multiple axons with myelin sheaths. - **Functions:** Oligodendrocytes are responsible for producing and maintaining the myelin sheaths that insulate and enhance the conduction speed of axons in the CNS. They play a critical role in axon support and signal transmission. **In the Peripheral Nervous System (PNS):** 4. **Schwann Cells (Neurolemmocytes):** - **Structure:** Schwann cells are elongated cells that wrap around and myelinate individual axons in the PNS. - **Functions:** Schwann cells are the equivalent of oligodendrocytes in the PNS. They produce myelin sheaths around axons, providing insulation and promoting rapid signal transmission. Schwann cells also assist in axon regeneration after injury. 5. **Satellite Cells:** - **Structure:** Satellite cells are flat, supportive cells that surround neuronal cell bodies in sensory and autonomic ganglia. - **Functions:** Satellite cells provide mechanical support and regulate the extracellular environment around neuronal cell bodies in sensory and autonomic ganglia. They help maintain optimal conditions for neuronal function. 6. **Enteric Glial Cells (Found in the Enteric Nervous System - Part of the PNS):** - **Structure:** Enteric glial cells are similar in structure to astrocytes, with numerous branching processes. - **Functions:** Enteric glial cells are found in the gastrointestinal tract and support the neurons of the enteric nervous system. They assist in regulating gastrointestinal functions, including peristalsis and digestion. In summary, neuroglia are essential for the proper functioning and health of the nervous system. Astrocytes, microglia, and oligodendrocytes are primarily found in the CNS, while Schwann cells, satellite cells, and enteric glial cells are located in the PNS. Each type of neuroglia serves specific roles, including structural support, insulation, immune defense, and maintenance of the neural environment.

Neuroglia, also known as glial cells, are non-neuronal cells in the nervous system that provide various supportive functions for neurons. There are several types of neuroglia, and they can be categorized into two main groups based on their location within the nervous system: those found in the central nervous system (CNS) and those found in the peripheral nervous system (PNS). Here are six types of neuroglia, their structures, functions, and their distribution in the CNS and PNS: **In the Central Nervous System (CNS):** 1. **Astrocytes:** - **Structure:** Astrocytes have numerous branching processes that radiate from a central cell body. They often have star-shaped appearances. - **Functions:** Astrocytes provide structural support to neurons, help regulate the extracellular environment by maintaining ion balance, and form the blood-brain barrier, which restricts the passage of substances from the bloodstream into the brain. They also play a role in synaptic signaling and the repair of neural tissue. 2. **Microglia:** - **Structure:** Microglia are small, highly motile cells with multiple branching processes. - **Functions:** Microglia are the resident immune cells of the CNS. They monitor the brain for pathogens, damaged cells, and debris. When activated, they function as phagocytes, engulfing and removing foreign invaders and cellular debris. 3. **Oligodendrocytes:** - **Structure:** Oligodendrocytes have a round or oval cell body with multiple extensions, each of which can wrap around and insulate multiple axons with myelin sheaths. - **Functions:** Oligodendrocytes are responsible for producing and maintaining the myelin sheaths that insulate and enhance the conduction speed of axons in the CNS. They play a critical role in axon support and signal transmission. **In the Peripheral Nervous System (PNS):** 4. **Schwann Cells (Neurolemmocytes):** - **Structure:** Schwann cells are elongated cells that wrap around and myelinate individual axons in the PNS. - **Functions:** Schwann cells are the equivalent of oligodendrocytes in the PNS. They produce myelin sheaths around axons, providing insulation and promoting rapid signal transmission. Schwann cells also assist in axon regeneration after injury. 5. **Satellite Cells:** - **Structure:** Satellite cells are flat, supportive cells that surround neuronal cell bodies in sensory and autonomic ganglia. - **Functions:** Satellite cells provide mechanical support and regulate the extracellular environment around neuronal cell bodies in sensory and autonomic ganglia. They help maintain optimal conditions for neuronal function. 6. **Enteric Glial Cells (Found in the Enteric Nervous System - Part of the PNS):** - **Structure:** Enteric glial cells are similar in structure to astrocytes, with numerous branching processes. - **Functions:** Enteric glial cells are found in the gastrointestinal tract and support the neurons of the enteric nervous system. They assist in regulating gastrointestinal functions, including peristalsis and digestion. In summary, neuroglia are essential for the proper functioning and health of the nervous system. Astrocytes, microglia, and oligodendrocytes are primarily found in the CNS, while Schwann cells, satellite cells, and enteric glial cells are located in the PNS. Each type of neuroglia serves specific roles, including structural support, insulation, immune defense, and maintenance of the neural environment.