Astrocyte

Definition

Astrocytes are a type of glial cell found in the central nervous system (CNS). They are the most numerous and diverse cells in the brain, performing a wide range of critical functions to support and protect neurons.

5 Must Know Facts For Your Next Test

1. Astrocytes have numerous branching processes that interact with neurons, blood vessels, and other glial cells in the CNS.
2. They provide structural and metabolic support for neurons, regulating the extracellular environment and maintaining the blood-brain barrier.
3. Astrocytes play a crucial role in the uptake and recycling of the neurotransmitter glutamate, preventing excitotoxicity.
4. During injury or disease, astrocytes become reactive, undergoing morphological and functional changes to protect the CNS.
5. Astrocytes are involved in the formation and maintenance of the blood-brain barrier, which controls the movement of substances between the bloodstream and the brain.

Review Questions

• Describe the primary functions of astrocytes in the central nervous system.
  • Astrocytes perform a variety of essential functions in the central nervous system. They provide structural and metabolic support for neurons, regulating the extracellular environment and maintaining the blood-brain barrier. Astrocytes also play a crucial role in the uptake and recycling of the neurotransmitter glutamate, preventing excitotoxicity. Additionally, astrocytes are involved in the formation and maintenance of the blood-brain barrier, which controls the movement of substances between the bloodstream and the brain.
• Explain how astrocytes respond to injury or disease in the central nervous system.
  • During injury or disease, astrocytes become reactive, undergoing morphological and functional changes to protect the central nervous system. This reactive astrocyte response involves the upregulation of specific proteins and the alteration of astrocyte morphology, allowing them to form a protective scar-like barrier around the site of injury or disease. Reactive astrocytes also play a role in the clearance of cellular debris, the regulation of inflammation, and the modulation of neuronal function to promote tissue repair and recovery.
• Analyze the relationship between astrocytes and the blood-brain barrier, and discuss the importance of this relationship for the central nervous system.
  • Astrocytes are intimately involved in the formation and maintenance of the blood-brain barrier, a highly selective semipermeable membrane that separates the circulating blood from the brain and extracellular fluid in the central nervous system. Astrocytes extend their end-feet processes to closely interact with the endothelial cells that line the blood vessels, providing structural and functional support to the blood-brain barrier. This astrocyte-blood vessel interface is crucial for regulating the movement of substances between the bloodstream and the brain, ensuring the proper exchange of nutrients, gases, and waste products while preventing the entry of harmful substances. The integrity of the blood-brain barrier is essential for maintaining the homeostasis and optimal functioning of the central nervous system.

Related terms

Glial Cells:

Non-neuronal cells in the central nervous system that provide support and protection for neurons.

Neuron:

The fundamental unit of the nervous system responsible for receiving, processing, and transmitting electrical signals.

Blood-Brain Barrier:

A highly selective semipermeable membrane that separates the circulating blood from the brain and extracellular fluid in the central nervous system.