Question

Question 24 3 pts What 3 specialized features create the blood brain barrier? What is the importance of the blood brain barrier? Where is the blood brain barrier reduced? Can the blood brain barrier make it difficult to treat certain nervous system conditions? HTML Editore BIVA-A-I EX X ! - EV GOVO 12pt

Answer 1

It is made up of capillary endothelial cells and basement membrane, neuroglial membrane, and glial podocytes, i.e., projections of astrocytes. These 3 components work in synchronicity with one another to limit the entry of various substances into the cerebral blood flow and subsequently the brain parenchyma.

The purpose of the blood–brain barrier is to protect against circulating toxins or pathogens that could cause brain infections, while at the same time allowing vital nutrients to reach the brain.

Four areas of the brain are not protected by the blood-brain barrier. These areas include the posterior pituitary gland, pineal gland, the median eminence of the hypothalamus and the area postrema.

The brain also is protected by a physical and biochemical wall called the blood-brain barrier that blocks toxins from reaching brain cells. These defenses, in particular the blood-brain barrier, also make it more difficult to treat disease of the brain, including cancer.

IN DETAIL:

The blood–brain barrier (BBB) is a highly selective semipermeable border of endothelial cells that prevents solutes in the circulating blood from non-selectively crossing into the extracellular fluid of the central nervous system where neurons reside.

The blood–brain barrier (BBB) is a highly selective semipermeable border of endothelial cells that prevents solutes in the circulating blood from non-selectively crossing into the extracellular fluid of the central nervous system where neurons reside.^[1] The blood-brain barrier is formed by endothelial cells of the capillary wall, astrocyte end-feet ensheathing the capillary, and pericytes embedded in the capillary basement membrane.^[2] This system allows the passage of some molecules by passive diffusion, as well as the selective transport of various nutrients, ions, organic anions, and macromolecules such as glucose, water and amino acids that are crucial to neural function.

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.

Specialized brain structures participating in sensory and secretory integration within brain neural circuits—the circumventricular organs and choroid plexus—have highly permeable capillaries.