Question

Explain the processes involved when drugs such as cocaine, marijuana, mescaline or alcohol enter the brain. You may draw a diagram to amplify your explanation.

Answer 1

The brain is a highly specialized organ. One of its marvels is that it is not easy for many moleculaes to get into the brain. It is naturally protected by a barrier from potentially harmfrul molecules by what is known as a “Blood brain barrier.”

However some drugs have the ability to cross this barrier. These are such that they can dissolve in fats or lipids, hence called lipophilic. Nicotine, marijuana, heroin and ethanol which is present in alcohol are lipophilic and do manage to enter the brain.

Transporters carry these compounds across the barrier through a process called active transport.

The example of alchohol:

At first alcohol is absorbed by the cell membranes lining the GI tract into the blood capillaries. IN the bloodstream it travels to the heart, then to the lungs and back again to the heart from where the arteries take it to all the organs of the body.

Ehanol reaches the arteries that lie between the brain and the skull. The capillaries that branch out from the arteries get into the brain. Ethanol passes through these capillaries which are tightly packed together and do not have fenestrae unlike capillaries elsewhere in the body.

Because ethanol is lipophilic it moves in the capillaries by passive diffusion and through the protective astrocyte wrap ( a feature of the capillaries in the brain, astrocytes are accessory cells that wrap themselves around capillaries same as insulation wraps around wires)

The brain is a highly specialized organ. One of its marvels is that it is not easy for many moleculaes to get into the brain. It is naturally protected by a barrier from potentially harmfrul molecules by what is known as a “Blood brain barrier.”

However some drugs have the ability to cross this barrier. These are such that they can dissolve in fats or lipids, hence called lipophilic. Nicotine, marijuana, heroin and ethanol which is present in alcohol are lipophilic and do manage to enter the brain.

Transporters carry these compounds across the barrier through a process called active transport.

The example of alchohol:

At first alcohol is absorbed by the cell membranes lining the GI tract into the blood capillaries. IN the bloodstream it travels to the heart, then to the lungs and back again to the heart from where the arteries take it to all the organs of the body.

Ehanol reaches the arteries that lie between the brain and the skull. The capillaries that branch out from the arteries get into the brain. Ethanol passes through these capillaries which are tightly packed together and do not have fenestrae unlike capillaries elsewhere in the body.

Because ethanol is lipophilic it moves in the capillaries by passive diffusion and through the protective astrocyte wrap ( a feature of the capillaries in the brain, astrocytes are accessory cells that wrap themselves around capillaries same as insulation wraps around wires)