The Neuron and Neural Firing: Neural Communications and the Endocrine System

Question 1

Neuron

Answer 1

nerve cell; building blocks of the brain/nervous system
○ Receive, process, & transmit information between body & brain

Question 2

Cell body

Answer 2

part of a neuron that contains the nucleus; cell’s life-support center

Question 3

Dendrite

Answer 3

bushy, branchy extensions that receive & integrate messages from other neurons; extend off cell
body, & conduct messages toward cell body

Question 4

Axon

Answer 4

extension that carries an electrical signal (called an action potential) & passes messages through its
branches to other neurons/muscles/glands
■ Axon often covered in a protective myelin sheath - fatty tissue layer segmentally encasing axons of
some neurons; enables vastly greater transmission speed of neural messages

Question 5

Glial (glue) cells

Answer 5

cells in nervous system that support, nourish, & protect neurons; also play a role in
learning, thinking, & memory
■ “Worker bees”; more complex the brain, the more glial cells

Question 6

The Neural Impulse

Answer 6

Neurons transmit messages when stimulated by our senses/neighboring neurons

Question 7

Action potential

Answer 7

a neural impulse; a brief electrical charge that travels down an
axon & triggers release of chemical messengers to the dendrites of other neurons
○ Neurons generate electricity from chemical events (electrochemical event - similar
to batteries)
■ Communication between neurons is chemical; communication within a
neuron is electrical

Question 8

resting potential

Answer 8

When a neuron is inactive (called resting potential), the inside is negatively charged & the outside membrane is positively charged

Question 9

excitatory neural signals

Answer 9

activate a neuron, causing depolarization

Question 10

inhibitory neural signals

Answer 10

stopping a neuron from activating

Question 11

if excitatory signals exceed inhibitory signals, depolarization may reach a neural threshold

Answer 11

level of stimulation required to trigger a neural impulse

Question 12

Refractory period

Answer 12

brief resting pause after firing; action potential cannot occur again until axon returns to its resting potential Increasing level of stimulation above the threshold will not increase the neural impulses intensity

Question 13

All-or-none response

Answer 13

neuron’s reaction of either firing (with a full-strength response) or not firing
● A strong stimulus, like a strong smell or something very painful, can trigger more neurons to fire, but
not intensity of the action potential

Question 14

Synapse

Answer 14

junction between axon tip of sending neuron (called the axon terminal or terminal
button) & dendrite or cell body of receiving neuron; also called synaptic gap or synaptic cleft

Question 15

neurotransmitters

Answer 15

chemical messengers that cross the synaptic gaps between neurons; released by sending neuron & bind to receptor sites on receiving neuron - influence whether that neuron will generate a neural impulse (excitatory or inhibitory)

Question 16

reuptake

Answer 16

Excess neurotransmitters drift away in synapse & are broken down by enzymes or are
reabsorbed into the sending neuron through reuptake

Question 17

Endocrine system

Answer 17

body’s “slow” chemical communication system; a set of glands & fat tissue that secrete hormones into the bloodstream

Question 18

Hormones

Answer 18

chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, & affect other tissues (some are identical to neurotransmitters)
○ Slower acting but longer lasting than neurotransmitters
■ Hormones to know: oxytocin, adrenaline, leptin, ghrelin, melatonin, & oxytocin

Question 19

Pituitary gland

Answer 19

most influential gland (also called the “master gland”); secretes growth hormones & oxytocin (enables orgasm, labor contractions, & milk production)

Question 20

Psychoactive drugs

Answer 20

chemical substance that alters the brain, causing changes in perceptions & moods

Question 21

Substance use disorder

Answer 21

disorder characterized by continued substance use despite resulting life disruption

Question 22

Depressants

Answer 22

drugs such as alcohol, barbiturates (tranquilizers), & opioids that calm neural activity & slow body functions

Question 23

Barbiturates

Answer 23

drugs that depress central nervous system activity, reducing anxiety but impairing memory & judgment (also called tranquilizers)
■ Often used as sleep aids
■ Examples: Nembutal, Seconal, & Amytal

Question 24

Opioids

Answer 24

opium & its derivatives; they depress neural activity, temporarily lessening pain & anxiety
■ Stimulates the production of endorphins (agonist) - after continued use, the brain stops naturally producing endorphins, leading to withdrawal (negative symptoms associated with stopping the use of a drug) & addiction
■ Examples: heroin, Oxycontin, Vicodin, methadone, codeine

Question 25

Stimulants

Answer 25

drugs that excite neural activity & speed up body functions

Question 26

Nicotine

Answer 26

addictive chemical found in tobacco
■ As addictive as heroin & cocaine
■ Can develop tolerance (continuously needing more for the same effect) & withdrawal symptoms, such as anxiety,
insomnia, cravings, & distractibility
■ Smoking is the leading cause of preventable death in the US

Question 27

Cocaine

Answer 27

Cocaine - powerfully addictive stimulant deriving from the coca plant ; produces a rush of euphoria that depletes dopamine, serotonin, & norepinephrine
■ Energetic, euphoric state followed a depressive crash
■ Drug targets the brain’s reward pathways

Question 28

Alcohol

Answer 28

slows brain activity that controls judgment & inhibitions; disrupts memory formation; reduces self-awareness ■ Alcohol use disorder - prolonged & excessive drinking, even though there are negative consequences

Question 29

Methamphetamine

Answer 29

stimulates neural activity of dopamine; effect lasts much longer than cocaine (8 hours vs. 1 hour)

Question 30

Ecstasy (MDMA/Molly)

Answer 30

triggers dopamine & serotonin & blocks reuptake, leading to feelings of euphoria, love, &
connectedness
■ Known as the “hug drug”
■ Repeated use can cause damage to the brain’s serotonin-producing neurons
■ Classified as a stimulant & mild hallucinogen

Question 31

Hallucinogens

Answer 31

psychedelic (“mind-manifesting”) drugs that distort perceptions & evoke sensory images in the absence of sensory input; can develop a tolerance, but most are not addictive
■ Often see geometric forms, meaningful images, replays of past emotional experiences, & ego-death at large doses
■ Sensations are similar to a near-death experience - altered state of consciousness reported after a close brush with
death (such as cardiac arrest)

Question 32

LSD (acid)

Answer 32

powerful hallucinogen that produces feelings of euphoria, shapes & color perception; sometimes can cause
feelings of detachment or panic (known as a “bad trip”)

Question 33

Marijuana

Answer 33

mild hallucinogenic plant; contains THC (delta-9-tetrahydrocannabinol), which produces mild hallucinations,
delusions, & sometimes anxiety
■ Can develop a tolerance (but is not physically addictive)
■ Has been found to be very effective in relief of chronic pain, chemotherapy-related nausea, & muscle pain associated
with multiple sclerosis