Neurons & Neural Firing

Neurons

The building blocks of the nervous system. Send, receive, and process messages throughout the body, and release neurotransmitters

Cell Body (Soma)

is made up of a nucleus that determines when the neuron has reached the threshold to fire. Also carries out basic metabolic functions of the neuron

Dendrites

receive messages from other neurons and send them to the neuron

Axon

The “tail” of the neuron where electrical signals are conducted and carried out to communicate with the brain

Myelin Sheath

white fatty substance an axon is wrapped in. Insulates axon and increases speed of action potential = faster communication

Synapse

gap between terminal buttons of presynaptic (sending) neuron and dendrites of postsynaptic (receiving) neuron

Glial Cells

support cells that hold together the message-sending neurons and support their functioning. Some supply nutrients, myelin, or function as immune cells in the brain

Reflex arc

neural pathways that controls a reflex. acts on an impulse before it reaches the brain

sensory neurons

contain afferent nerve fibers in axon which carry messages from sensory organs (eyes, skin, etc.) toward brain/spinal cord (CNS). Interneurons then connect with motor neurons to send messages to muscles/glands resulting in a reflex

motor neurons

transmit signals from brain to muscles/glands allowing us to talk, move, etc.

Interneurons

Connects sensory and motor neurons in CNS

Psychoactive drugs

Drugs such as depressants like alcohol, opioids like heroin, hallucinogens like marijuana, or stimulants like caffeine or cocaine

substance use disorder

a mental disorder that affects ones behavior and brain due the inability to control the use of certain substances. There are many symptoms such as cognitive, behavioral, and physiological symptoms.

antagonist

a drug that inhibits/slows down the action of a neurotransmitter

Stimulants

a type of psychoactive drug that increases the levels of the neurotransmitters dopamine and norepinephrine. Ex) Caffeine & cocaine

caffeine

A type of stimulant that increases the levels of dopamine and norepinephrine (agonist). It is the most commonly consumed psychoactive substance in the world.

Side Effects: restlessness, shakiness, fast heart rate, dizziness

cocaine

A type of stimulant that increases the levels of dopamine (agonist).

Side Effects: increased blood pressure/heart rate, hallucinations, seizures, violent behavior

methamphetamines

a type of stimulant that increases the levels of dopamine. Can be used to treat ADHD.

Side effects: decreased appetite, nausea, increased body temp.

ecstasy

a type of stimulant that increases the levels of serotonin, dopamine, and norepinephrine

Side effects: sweating, nausea, memory problems, decreased appetite, blurry vision

opiods

a type of psychoactive drug that blocks pain receptors by increasing endorphins (painkiller). Ex) heroin

Heroin

A type of opioid that increases the levels of dopamine and increases endorphins

Side effects: euphoria, vomitting, pain relief, small pupils

action potential

the message/electrical impulse moving down the axon and the neuron fires

all or nothing principle

a neuron either fires or it doesn’t. fires at threshold of -55 mv

depolarization

after the neuron fires, the message travels down the axon and positive ions (sodium) flows in through the axon before moving onto the next

reuptake

when a neuron reabsorbs a neurotransmitter after it has already been released

multiple sclerosis

A neurotransmitter disorder where there is too much glutamate and not enough GABA. Too much glutamate causes excitotoxicity, killing neurons leading to a communication block between brain and body. GABA usually stops neurons from firing but since there isnt enough, more neurons are firing.

Side Effects: vision loss in one eye, weak leg muscles (trouble walking), dizziness, colors look dull

neurotransmitters

they are released from terminal buttons to synapse and allow neurons to communicate with each other. Ex) dopamine, serotonin, glutamate, etc.

excitatory neurotransmitters

tells the neurons to fire

inhibotory neurotransmitters

prevents neurons from firing

dopamine

a type of neurotransmitter (excitory & inhibitory)

Function: pleasure, muscular control, learning, attention

When too high: aggression, poor decision making,

Too low: lack of motivation, poor concentration, moody

disorders: high-schizophrenia low-depression, anxiety, parkinsons disease

norepinephrine

excititory neurotransmitter

function: alertness, arousal (fight or flight)

too high: high blood pressure, anxiety, sweating

too low: low excitement, poor concentration, depressed

disorders: high-insomnia, PTSD low-Parkinsons disease

GABA

inhibitory neurotransmitter (prevents neurons from firing)

too high: seizures, oversleeping, lack of energy

too low: poor impulse control, seizures in the brain

Disorders: high-hypersomnia low-bipolar, mania

substance p

excititory neurotransmitter (carries pain signals)

too high: high levels of pain sensitivity, anxiety

too low: reduced pain sensitivity, mood changes, unstable bones

disorders: high-migranes, anxiety, eczema, arthritis, chronic pain low-depression, asthma, migranes, eczema

serotonin

inhibitory neurostansmitter

function: appetite, sleep, mood

too high: agitation, restlessness

too low: sadness, fatigue, suicidal thoughts

disorders: high-serotonin syndrome (hallucinations, confusion, restlessness) low-anxiety

glutamate

excitatory neurotransmitters (helps neurons fire)

too high: excitotoxicity (neurons are killed), stroke

too low: poor concentration, death, mental exhaustion

disorders: high-alzheimers, epilepsy low-psychosis, insomnia

acetylcholine

excitatory neurotransmitter

function: voluntary muscle movements, memory, learning

too high: increased salivation, blurred vision

too low: weak muscles, paralysis, learning impairments, memory impairments

disorders: low-dementia, alzheimers

hormones

chemical messangers that help help regulate biological processes in the body

leptin

a type of hormone that helps regulate body weight and energy

melatonin

a type of hormone that helps regulate sleep and wake cycles in circadian rhythms. Increases at night and is almost non existent in the morning

refractory period

positively charged ions leave the axon and the neuron can’t be fired until it reaches resting potential

resting potential

where the axon is more negative on the inside and more positive on the outside. (at -70 mv)

threshold

the bare minimum a neuron will fire (-55mv)

myasthenia gravis

an autoimmune disease that causes muscle weakness

endorphins

hormones produced in the brain that act as natural pain killers and can improve mood

addiction

feeling like you keep needing more of something. not being able to control ones self

agonist

drugs that enhance or amplify the action of a certain neurotransmitter

reuptake inhibiter

drug that prevents the reuptake of a neurotransmitter

depressants

a drug that slows down brain activity cause muscles to relax and provide a calming feeling

barbiturates

a type of depressant that is used for sedatives

alcohol

a type of depressant that increases GABA and dopamine (agonist)

hallucinogens

provides an increase of serotonin and alters perspective

near death experience

a vivid/life changing experience that when someone has begun the process of dying

marijuana

a type of hallucinogen that increases serotonin and dopamine (agonist)

LSD

a drug used to treat alcoholism

tolerance

the ability to tolerate a certain substance. When you have increased amounts of a certain substance you can increase a tolerance for that substance

withdrawl

when you take something away and they want it back so badly. When you take away a drug it can lead to certain symptoms as the neurotransmitters are being produced by the body

endocrine system

network of glands to produce hormones into bloodstream to regulate organ and cell functions

adrenaline

a hormone that helps one react to stressful/dangerous situation.

ghrelin

a hormone that increases appetite

oxytocin

hormone that plays role in human behavior and reproduction