Answer:
The capillary membranes that filter substances moving between the cerebral blood vessels and the brain are called the blood-brain barrier.
Step-by-step explanation:
Capillaries are the smallest type of blood vessel in the body. Capillaries enable the exchange of substances between the blood and surrounding tissues. They are thinner than arteries and veins, because their walls are made up of only a single layer of endothelial cells, the flat cells that line all blood vessels. Capillaries function to deliver nutrients and oxygen to tissues and remove the byproducts of cellular reactions, such as water and carbon dioxide.
The Blood-brain barrier is an anatomic and biochemical barrier that protects the brain from potentially harmful substances. It is a highly selective membrane barrier at the brain microvessel level which aids transport between the systemic circulation and the central nervous system.
The Blood–brain barrier restricts the passage of pathogens, aids in ensuring solutes are diffused in the blood, and hydrophilic or large molecules into the cerebrospinal fluid, while allowing the diffusion of hydrophobic molecules (oxygen, carbondioxide, hormones) and small polar molecules.