Blood brain barrier is formed by a)Astrocytesb)Oligodendrocytesc)Glial cellsd)Microglial cellsCorrect answer is option 'A'. Can you explain this answer?

Question

Answer

Astrocytes contribute to induction and maintenance of the blood–brain barrier through paracrine interactions with the pericytes and endothelial cells. Astrocytes secrete classes of factors with either barrier-promoting or barrier-disrupting effects depending on signals received from neurons and/or endothelial cells.

The blood-brain barrier restricts the passage of pathogens, the diffusion of solutes in the blood, and large or hydrophilic molecules into the cerebrospinal fluid, while allowing the diffusion of hydrophobic molecules (O2, CO2, hormones) and small polar molecules.[4] Cells of the barrier actively transport metabolic products such as glucose across the barrier using specific transport proteins

Answer

Astrocytes have star-shape morphology and are the most abundant CNS glial cell type. They play essential functions in blood brain barrier maintenance, neuronal survival, and in synapse formation, strength, and turnover.

Answer

Understanding the Blood-Brain Barrier
The blood-brain barrier (BBB) is a crucial structure in the central nervous system that regulates the passage of substances between the blood and the brain.

Formation of the Blood-Brain Barrier
- The BBB is primarily formed by endothelial cells of the brain's capillaries, which are tightly packed together.
- Astrocytes play a vital role in the development and maintenance of the BBB.

Role of Astrocytes
- Astrocytes are a type of glial cell that provide structural and metabolic support to neurons.
- Their end-feet encase the blood vessels and release signaling molecules that promote the tight junctions between endothelial cells.

Importance of Tight Junctions
- Tight junctions between endothelial cells prevent the free passage of substances, ensuring that only selective molecules (like glucose and amino acids) can enter the brain.
- This selectivity protects the brain from toxins and pathogens, while also maintaining homeostasis.

Other Glial Cells
- Oligodendrocytes and microglial cells also play important roles in the CNS, but they are not directly involved in forming the BBB.
- Oligodendrocytes are responsible for myelination of neurons, while microglial cells act as immune defenders in the brain.

Conclusion
In summary, while the endothelial cells form the physical barrier, it is the astrocytes that are essential for the integrity and functionality of the blood-brain barrier, making option 'A' the correct answer.

Answer

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