THE BRAIN

AND THE EFFECTS OF ALCOHOL AND OTHER DRUGS

THE BRAIN

Command center of your bodyWeighs about 3 poundsDifferent 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 centerBreathing, 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 againWalking, 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 CEREBRUMDivided into right and left hemispheres

Thinking part of the brain- most highly developedStore and process language, math and strategies

Also contains the LIMBIC SYSTEMResponsible for survivalCauses 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 AmygdalaMemory

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 partsCell 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.