"Astrocytes" are present in

Question

Question

This question was previously asked in

RRB Pharmacist Exam Paper 2019

Answer 1

Correct Answer: Blood brain barrier

Explanation:

Astrocytes: These are a type of glial cell found in the central nervous system (CNS). They play numerous roles including maintaining the extracellular ion balance, providing nutrients to nervous tissue, and repairing the brain and spinal cord following traumatic injuries.
Blood-brain barrier (BBB): Astrocytes are critically involved in the formation and maintenance of the blood-brain barrier. They extend their end-feet processes to cover the blood vessels in the brain, which helps to ensure the selective permeability of the barrier. This is vital for protecting the brain from harmful substances in the blood while allowing essential nutrients to pass through.

Explanation of Other Options:

Blood - cerebrospinal fluid barrier

This barrier is primarily maintained by the ependymal cells lining the ventricles of the brain and the choroid plexus epithelium, not by astrocytes.

Blood placental barrier

This barrier is involved in the exchange of substances between the maternal and fetal blood supply, and it is comprised of trophoblast cells in the placenta. Astrocytes are not involved in this barrier.

Cell membrane barrier

This is a more general term referring to the plasma membrane of individual cells, which controls the ingress and egress of substances. Astrocytes contribute to cell membranes at their own cellular level but are not categorized as forming any specific "cell membrane barrier" relevant to the options listed.

Additional Information:

Other Roles of Astrocytes: Beyond their involvement in the blood-brain barrier, astrocytes also play roles in neurotransmitter uptake and release, ion homeostasis, and modulation of synaptic function.

Conclusion:

Astrocytes are primarily associated with the blood-brain barrier, where they help regulate the movement of substances between the blood and the brain, ensuring a protected and stable environment for neurons.