Home » Module 2: The ABCs of Intoxication » Content: gaining Alcohol come the Brain: cross the Blood-Brain-Barrier


For alcohol to reason intoxication, the must gain into the brain. When alcohol is consumed, it pipeline the cradle (GI) tract to get in the bloodstream. This process is referred to as “absorption”; alcohol is easily absorbed through cabinet membranes lining the GI tract right into the blood capillaries. When in the bloodstream, ethanol is lugged to the heart, where it move to the lung and back to the heart to be pumped through the arterial system to all organs in the body.

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Learn how ethanol is took in into the bloodstream through filtration and passive diffusion.

Learn how ethanol is transported with the bloodstream to major organs.

Ethanol travel to the brain within the arteries that lie between the skull and the brain itself. These arteries branch out right into capillaries, i m sorry dive deep into the brain tissue. Ethanol must pass v these capillaries to reach all cells (e.g., neurons) in the brain. For many molecules, it’s no so simple to acquire into the brain. There is a obstacle called the blood-brain-barrier that protects the brain from foreign substances that could potentially harm this highly specialized organ. Unfortunately for the brain, there is no obstacle for ethanol. Ethanol the cross the blood-brain-barrier really easily. This is as result of its chemistry characteristics—although the is rather polar, the is also lipophilic, and so it mixes quickly with the fat in the membrane.

Learn more about the chemical qualities of ethanol.

The blood-brain-barrier actually consists of several components. These include:

Tight junctionsTo ensure the the endothelial cells continue to be “glued” together, specialized proteins reside in the cabinet membranes creating connections called tight junctions. These junctions protect against the activity of huge solutes in between the endothelial cells right into the brain tissue.

What makes it so easy for ethanol to overcome the blood-brain-barrier? In the case of other biological membranes, ethanol moves across by filtration (moving with water spaces since it disappear in water) and by passive diffusion (moving through the concentration gradient with the membrane itself due to the fact that it likewise dissolves in lipid). In the brain capillaries, the lipophilic character of the ethanol permits it to move by passive diffusion throughout the endothelial cell membrane and through the astrocyte wrap. Ethanol’s little mass helps too!

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Figure 2.3 The blood-brain-barrier consists of tightly-packed capillaries without any type of holes (fenestrae) that are wrapped v a class of fat by astrocytes. Efflux transporters (proteins) aid to expel foreign substances that could sneak v the capillary membrane.

Review how ethanol crosses biological membranes

Although the physics restrictions applied by the blood-brain-barrier limit the distribution of drugs or toxin to the brain, other small lipophilic drugs have the right to diffuse passively across the blood-brain-barrier including, nicotine, marijuana, and also heroin. In addition, water soluble nutrient such as glucose, and big water dissolve molecules such as vitamins, perform get throughout to reach all cells in the brain. This compounds are carried throughout the obstacle by proteins referred to as transporters. This process requires energy, and also is known as active transport.

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The blood-brain barrier provides a great of security for the mind from harmful or foreign substances. Committed capillary membranes in the mind are important to avoid the nonselective passage of molecules across the blood-brain barrier.