THE BRAIN
AND THE EFFECTS OF
ALCOHOL AND OTHER DRUGS
THE BRAIN
Command center of your body
Weighs about 3 pounds
Different centers which control
different things
Despite being 90-95 percent of its
adult size by age six, the brain is still
“under construction” until age 18.
BRAIN STEM
Vital life center
Breathing, swallowing, heart beat, sleeping
Things you never think about
Gulping large amounts of alcohol in a short
time can stop the breathing reflex and
cause death
CEREBELLUM
Responsible for things you learn once and
never have to think about again
Walking, riding a bike, throwing a ball
Higher thought processes like music and
complex math problems
Changes drastically during teen years,
increasing its number of nerve cells and
connections to the rest of the brain
CEREBRAL CORTEX
Also known as CEREBRUM
Divided into right and left hemispheres
Thinking part of the brain- most highly
developed
Store and process language, math and
strategies
Also contains the LIMBIC SYSTEM
Responsible for survival
Causes you to be hungry for good food and to enjoy
the company of others;
Emotions related to fear, anger and love
LIMBIC SYSTEM
Hippocampus and Amygdala
Memory
v Drugs can have powerful control of the brain
stem and limbic system. These systems can
override our cortex in controlling our
behavior.So, we do things without thinking!
NERVE CELLS AND
NEUROTRANSMISSIONS
NEURON- three parts
Cell body that directs all activities of the
neuron
Dendrites that receive messages-many fibers
Axons that send messages-long single fiber
NEUROTRANSMISSION
• The transfer of a message (electrical
impulse) from the axon of one nerve cell to
the dendrites of another
• No direct contact. There is a chemical
release (neurotransmitters) into the space
between the axon and dendrites. This
space is called a synapse. The
neurotransmitters bind to receptors in the
dendrites.
NEUROTRANSMITTERS
• Chemical messengers, carrying
information from one neuron to
another.
MYELIN
A fatty substance that covers axons.
The more myelin an axon has, the faster
nerve impulses can travel.
– After puberty, the amount of myelin in
the brain increases dramatically, making
the brain much more efficient.
ADDICTION AND THE
BRAIN
• The brain is wired so if something is
pleasurable, you will tend to do it again.
• Life sustaining activities, such as eating,
activate nerve cells devoted to producing
and regulating pleasure.The
neurotransmitter involved is called
DOPAMINE.
• The pleasure circuit (dopamine system)
spans the brainstem, emotional limbic
system and the frontal cerebral cortex
ADDICTION
• Drug addiction alters the way the pleasure
center, as well as other parts of the brain,
functions.
• Almost all drugs affect chemical
neurotransmission
– Heroin and LSD mimic natural
neurotransmitters
– PCP blocks receptors
– Cocaine interferes with getting
neurotransmitters back where they belong
– Methamphetamines cause too many
neurotransmitters to be released
Prolonged drug use causes addiction.