Passive Transport
The blood-brain barrier utilizes passive transport as one of its mechanisms. Carrier cells play a crucial role in facilitating the transportation of various substances across the blood-brain barrier. The following substances can be transported by hitching a ride on these cells: carbohydrates, amino acids, nucleotides, fatty acids, vitamins, sodium, glucose, thyroid hormones, insulin, and leptin. Additionally, certain small molecules, such as oxygen, carbon dioxide, caffeine, ethanol, and barbiturates, can diffuse through the membrane without the need for a carrier.
Active Transport: Maintaining the Blood-Brain Barrier and Ion Concentration
Active transport is a crucial process that allows certain elements to cross the blood-brain barrier, safeguarding the central nervous system (CNS) from accumulating unwanted substances. By utilizing specific transporters, active transport ensures that these substances are carried back into the plasma, preventing any potential harm.
In addition to its protective function, active transport also plays a vital role in maintaining the ion concentration within the brain. It works by upholding high concentrations of sodium (Na) and low concentrations of potassium (K) in the CNS. This delicate balance is essential for the proper functioning of various reactions that regulate cerebral blood flow and pH levels in the brain.