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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.