Name: TED-ED】薬は脳にどのような影響を与えるのか？- サラ・ガロファロ (【TED-Ed】How do drugs affect the brain? - Sara Garofalo)
Uploaded: 2021-01-14T07:00:27.000Z
Duration: 5 min 5 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

or otherwise take some kind of medicine during their lives,

but most of us don't know anything about how these substances actually work.

How can various compounds impact the way we physically feel,

For the most part, this depends on how a drug alters the communication

There are a number of different ways that can happen.

any drug must first reach the bloodstream

on a journey that can take anywhere from seconds to hours,

depending on factors like how it's administered.

The slowest method is to take a drug orally

because it must be absorbed by our digestive system

Inhaling a drug gets it into the bloodstream faster.

And injecting a drug intravenously works quickest

because it pumps the chemicals directly into the blood.

Once there, the drug quickly reaches the gates of its destination, the brain.

The entrance to this organ is guarded by the blood-brain barrier,

which separates blood  from the nervous system

to keep potentially dangerous  substances out.

So all drugs must have a specific chemical composition

which gives them the key to unlock this barrier and pass through.

Once inside, drugs start to interfere with the brain's normal functioning

by targeting its web of neurons  and synapses.

Neurons are brain cells that have a nucleus, dendrites, and an axon.

Synapses are structures placed along the dendrites or the axon

which allow the exchange of  electrochemical signals between neurons.

Those signals take the form of chemicals called neurotransmitters.

Each neurotransmitter plays different roles in regulating our behaviors,

They can either inhibit  the receiving neuron,

creating a new electrochemical signal that spreads throughout the network.

Any leftover neurotransmitter usually gets degraded

or reabsorbed  into the transmitting neuron.

A drug's effectiveness stems  from its ability

to manipulate these synaptic transmissions at different phases of the process.

That results in an increase or a decrease

in the amount of neurotransmitters being spread.

For instance, common antidepressants, like SSRIs,

a neurotransmitter that modulates our moods.

This effectively pushes more of it into the neural network.

raise levels of serotonin  and noradrenaline,

Those same neurotransmitters also affect endorphin receptors,

And tranquilizers works by increasing the production of GABA

putting the person in a relaxed or sedated state.

These have powerful impacts on the brain that we're still trying to understand.

induces a long-lasting release of dopamine,

a neurotransmitter linked with the perception of reward and pleasure.

It also activates noradrenaline receptors,

and triggers the body's fight or flight response.

Cocaine blocks the reuptake of dopamine and serotonin,

And hallucinogenic drugs have some of the most puzzling effects.

They also have an impact  on the neural circuits

involved in perception, learning, and behavioral regulation,

which may explain why these drugs have such powerful impacts.

Even if some of these  effects sound exciting,

there are reasons why some of these drugs are highly controlled and often illegal.

Drugs have the power to alter  the brain's chemistry,

and repeated use can permanently rewire the neural networks

There's a lot we still don't know  about drugs and their effects,

But those we do know about are the ones we've studied closely,

As our knowledge grows about drugs and the brain,

for treating the many medical problems that puzzle researchers today.