Nervous System

Nervous system cells

Neurons

Glial cellsOBJ 43

Types of neuronssensory neuron(from senses)

interneuron(brain & spinal chord)

motor neuron(to muscle or gland…effector cells)

Human brain

1

2

3

4

56

7

8

Divisions of the nervous system

Nervous System PathwayOBJ 40

How messages travelA B C

DEF

GB

C D

E

Synapse

Synapse:

synapse

Junction between nerve cells 1st cell releases neurotransmitter to

trigger next cell

What are some examples of neurotransmitters?

Acetylcholine

Epinephrine (adrenaline)

Dopamine

Serotonin

Endorphins

OBJ 45

Simplest Nerve Circuit Reflex arc, or automatic response

signal only goes to spinal cord

essential actions don’t need to think or

make decisions about blinking balance pupil dilation startle

Drugs & the Nervous system

What happens when you interfere with neural communication?

Nicotine acts as a stimulant mimics acetylcholine triggers the release of dopamine,

making it addictive

Alcohol

Alcohol in drinks is actually ethyl alcohol

High concentrations can be toxic Alcohol is a depressant Excessive amounts of alcohol damages

liver, digestive system, AND NEURONS

Alcohol and teens Teens’ brains are specially geared for

optimal learning So, teens experience more severe

damage to brain due to alcohol use (more blackouts, more brain damage…smaller brain)

Drug effects What is going on when someone is addicted

to drugs? Opiate drugs (heroin, morphine) can mimic

endorphins (a feel-good NT) Body adjusts to higher amount of endorphin-

like chemicals, and can’t do without it Take more and more of the drug. Without it,

feel pain, nausea, chills, fever, depression

Drug effects Marijuana (THC) –

THC blocks the action of neurotransmitters in the brain affecting motor skills, memory, concentration

Long-term effects: loss of memory, inability to concentrate, lowered testosterone

Drug effects

Ecstasy (MDMA) Causes rush of serotonin Interferes with homeostasis (temp.) Feel depressed until body makes

enough of its own serotonin to feel ‘normal’ again

Destroys serotonin neurons axons and terminals

After exposure to MDMA for 4 days, it takes more than 7 years for your brain to recover.

Drug effects Hallucinogens

LSD PCP Interfere with neurotransmitters in brain

Drug effects Cocaine

Causes dopamine to be released Not enough is left for normal function,

so users become dependent on it

Even 100 days after a cocaine addict has stopped using drugs, the decreased metabolism in the brain's frontal area remains visible. This region of the brain influences behavior such as regulating impulsive and repetitive behavior, planning and organizing activities, and critical thinking.