How the Brain Works The Facts Visually Explained by DK (z-lib.org)

24

THE PHYSICAL BRAIN

Brain Chemicals 25

Normal dopamine levels

Dopamine is a neurotransmitter associated with feeling

pleasure. It creates a drive to repeat certain behaviors that

trigger feelings of reward, perhaps leading to addiction. While

some dopamine molecules bind to receptors on the receiving

neuron, unused dopamine is recycled by being pumped back

into the sending neuron and parceled up again.

Dopamine and cocaine

The effects of cocaine are a

product of its effects on the

neurotransmitter dopamine

at synapses in the brain.

Drinking large volumes of alcohol over a long

period alters mood, arousal, behavior, and

neuropsychological functioning. Alcohol’s

depressant effect both excites GABA and inhibits

glutamate, decreasing brain activity. It also

triggers the brain’s reward centers by releasing

dopamine, in some cases leading to addiction.

THE LONG-TERM EFFECTS OF ALCOHOL

With use of cocaine

Cocaine molecules are reuptake inhibitors of dopamine. When

dopamine is released, it moves into the synapse and binds to

receptors on the receiving neuron as normal. However, the

cocaine has blocked the reuptake pumps that recycle the

dopamine, so the neurotransmitter accumulates in a higher

concentration, increasing its effects on the receiving neuron.

SENDING (^) NEURO
N

REC

EIVING NEURON

RE

CE

PTO

R

RE

CEP

TOR

Dopamine

Cocaine

KEY

VE

SIC

LE

VE

SIC

LE

SYN

APSE

SY

NA

PSE

Cocaine blocks

dopamine’s path

back into

sending neuron

Unused dopamine

sucked back into

sending neuron

Dopamine

held in vesicles

inside sending

neuron

REC

EIVING NEURON

Once released,

some dopamine

bonds to receptors

on receiving

neuron

Concentration

of dopamine

in synapse

increases

Dopamine

released

SENDING (^) NEURO
N
US_024-025_Brain_chemicals.indd 25 20/09/2019 12:31