Microglia are the resident immune cells of the central nervous system (CNS). They act as the first and main form of active immune defense in the brain and spinal cord, providing a protective barrier and responding to pathological changes or injuries within the CNS.
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Microglia account for 10-15% of the total cell population in the adult human brain.
Microglia have a dynamic and highly motile nature, constantly surveying the CNS environment for potential threats or disturbances.
In their resting state, microglia have a ramified morphology with numerous branching processes that allow them to monitor their surrounding microenvironment.
Upon activation, microglia can transform into an amoeboid shape, enabling them to migrate, phagocytose, and release inflammatory mediators.
Microglia play a crucial role in the development, homeostasis, and repair of the CNS by regulating synaptic pruning, neurogenesis, and the removal of damaged or dying cells.
Review Questions
Describe the primary functions of microglia within the central nervous system.
Microglia are the resident immune cells of the central nervous system (CNS) and serve several critical functions. They act as the first line of defense, responding to pathological changes or injuries within the CNS. Microglia are responsible for surveilling the CNS environment, phagocytosing cellular debris and pathogens, and releasing inflammatory mediators to coordinate the immune response. Additionally, microglia play a vital role in the development, homeostasis, and repair of the CNS by regulating synaptic pruning, neurogenesis, and the removal of damaged or dying cells.
Explain how the morphological changes in microglia are associated with their functional roles.
Microglia exhibit a dynamic and highly motile nature, with their morphology closely linked to their functional roles. In their resting state, microglia have a ramified morphology with numerous branching processes, allowing them to constantly monitor their surrounding microenvironment. Upon activation in response to pathological changes or injuries, microglia can transform into an amoeboid shape, which enables them to migrate, phagocytose, and release inflammatory mediators. This morphological transformation is a crucial adaptation that allows microglia to transition from a surveillance role to an active immune response, facilitating their ability to protect the central nervous system.
Discuss the significance of microglia in the development, homeostasis, and repair of the central nervous system.
Microglia play a crucial and multifaceted role in the central nervous system (CNS) beyond their immune functions. During development, microglia regulate synaptic pruning, a process that helps refine neural connections and optimize neuronal circuitry. In the adult CNS, microglia contribute to homeostasis by supporting neurogenesis and the removal of damaged or dying cells. In the event of injury or disease, microglia undergo activation and migration to the site of disturbance, where they can phagocytose cellular debris, release inflammatory mediators, and facilitate tissue repair. This dynamic involvement of microglia in the developmental, homeostatic, and reparative processes of the CNS highlights their essential contribution to the overall health and function of the nervous system.
Star-shaped glial cells in the brain and spinal cord that provide support and protection for neurons, maintain the blood-brain barrier, and regulate the extracellular environment.
Glial cells that produce myelin, the insulating material that forms a protective sheath around the axons of neurons, enabling faster transmission of electrical signals.
The process by which cells, such as microglia, engulf and digest cellular debris, pathogens, or other foreign substances, playing a crucial role in the immune response.