The Chemical Mind: Crash Course Psychology #3
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The Chemical Mind: Crash Course Psychology #3


Say it’s late at night, you’re home alone
drifting off to sleep, just, entering that dream about Fritos, and then suddenly there’s
a banging at the door! Suddenly you’re wide awake and it feels like your heart’s gonna
explode. You jump up ready to run out the back door, possibly grab a Phillips head screwdriver
and stab it into the darkness until it sticks into something. Now whether it’s a Weeping
Angel or your neighbor looking to borrow a can of beans, it doesn’t really matter because
when you heard that sudden noise, your startled brain released an icy typhoon of chemicals.
And everything that’s now going through your mind, like your urge to flee, your urge to
defend yourself, that internal debate about whether Weeping Angels are even real and “Woah!
Where’s the cat?” All that? Is just a result of those chemicals. Our brains and our nervous systems and the
substances they produce and are always bathed in are amazingly complex nuanced systems.
And even though we’re always talking about our mental activities being somehow separate
from all the biological stuff going on in our bodies, in reality, the moods, ideas,
impulses, that flash through our minds are spurred by our biological condition. As psychologists
like to say, “Everything psychological is biological.” So one way to understand how
your mind works is to look at how the chemistry of your body influences how you think, sense,
and feel about the world around you. To do that, we begin at the simplest level, the
system with the smallest parts, it’s all about the neuron, baby. [Intro] Neurons, or nerve cells, are the building
blocks that comprise our nervous systems. Neurons share the same basic makeup as our
other cells, but they have electrochemical mojo that lets them transmit messages to each
other. Your brain alone is made up of billions of neurons, and to understand why we think
or dream or do anything, you gotta first understand how these little transmitters work. You actually
have several different types of neurons in your body, from ones that are less than a
millimeter long in your brain to ones that run the whole length of your leg! Yes, you
have cells as long as your legs, which is nothing compared to the hundred and fifty
feet the nerve cells of some dinosaurs had to be, I’m getting off topic, sorry. No matter how big a nerve is, they all have
the same three basic parts: the soma, dendrites, and axon. The soma, or cell body, is basically
the neuron’s life support; it contains all that necessary cell action like the nucleus,
DNA, mitochondria, ribosomes, and such. So, if the soma dies, the whole neuron goes with
it. The dendrites, as bushy and branch-like as the trees they’re named after, receive
messages and gossip from other cells. They’re the listeners, whispering what they hear back
to the soma. The axon is the talker. This long, cable-like extension transmits electrical
impulses from the cell body out to other neurons or glands or muscles. Whereas the dendrites
are short and bushy, the axon fiber is long, and, depending on what type of neuron it is,
is sometimes encased in a protective layer of fatty tissue, called the myelin sheath.
It’s almost like an insulated electrical wire, the myelin sheath speeds up the transmission
of messages, and if it degrades, as it does with those affected with multiple sclerosis,
those signals are degraded as well, eventually leading to lack of muscle control. Neurons transmit signals either when stimulated
by sensory input or triggered by neighboring neurons. The dendrites pick up the signal
and activate the neuron’s action potential, or firing impulse, that shoots an electrical
charge down the axon to its terminals and towards the neighboring neurons. The contact
points between neurons are called synapses. All those bushy little dendrites are decorated
with synapses that almost but don’t quite touch the neighboring axon in the tiniest
game of “I’m not touching you!” of all time. They’re less than a millionth of an inch apart.
And that microscopic cleft is called the synaptic gap. So, when an action potential runs down
to the end of an axon, it activates the chemical messengers that jump that tiny synaptic gap,
flying like that little air kiss and landing on the receptor sites of the receiving neuron.
Those messengers are neurotransmitters. Although neurotransmitters slide right into
their intended receptors like a key into a lock, they don’t stay bonded to the receiving
neuron. They just sort of pop out, having excited or inhibited the receiving neuron’s
trigger, then the extras immediately get reabsorbed by the neuron that released them in the first
place in a process called reuptake. Kinda like, “Here you go, oh, psych!” So neurons
communicate with neurotransmitters which in turn cause motion and emotion; they help us
move around, make jazz hands, learn, feel, remember, stay alert, get sleepy, and pretty
much do everything we do. Some of them just make you feel good, like
the endorphins we get flooded with after running ten miles or falling in love or eating a really
good piece of pie. We’ve got over 100 different kinds of these brilliant neurotransmitters
— some are excitatory and others are inhibitory, and all are good reminders that everything
psychological is also biological. Excitatory neurotransmitters rev up the neuron, increasing
the chances it will fire off an action potential. Norepinephrine is one you’re probably familiar
with, it helps control alertness and arousal. Glutamate is another, involved in memory,
but an over-supply of it can wig out the brain and cause seizures and migraines which is
why some people are sensitive to all that MSG, or monosodium glutamate, in their Ramen.
Inhibitory neurotransmitters on the other hand, chill neurons out, decreasing the likelihood
that the neuron will jump into action. GABA– gamma-aminobutyric acid– is a major inhibitory
neurotransmitter, and you’ve probably heard of serotonin which affects your mood and hunger
and sleep. Low amounts of serotonin are linked to depression, and a certain class of antidepressants
help raise serotonin levels in the brain. Some neurotransmitters like acetylcholine
and dopamine play both sides and can both excite or inhibit neurons depending on what
type of receptors they encounter. Acetylcholine enables muscle action and influences learning
and memory; Alzheimer’s patients experience a deterioration of their acetylcholine producing
neurons. Dopamine, meanwhile, is associated with learning, movement, and pleasurable emotions,
and excessive amounts of it are linked to schizophrenia as well as addictive and impulsive
behavior. So neurotransmitters are basically your nervous
system’s couriers. But they aren’t the only chemical messengers delivering the news; they’ve
got some competition brewing in the endocrine system. And if you’ve been through puberty,
you know what I’m talking about: hormones. Like neurotransmitters, hormones act on the
brain, and indeed some of them are chemically identical to certain neurotransmitters. Hormones
affect our moods, arousal, and circadian rhythm, they regulate our metabolism, monitor our
immune system, signal growth, and help with sexual reproduction. You could say that most
of them boil down to the basics: attraction, appetite, and aggression. Whereas neurons and synapses flick on and
off, sending messages with amazing speed, the endocrine system likes to take its time,
delivering the body’s slow chemical communications through a set of glands that secrete hormones
into the bloodstream where they’re ferried to other tissues, especially the brain. So while the nervous and endocrine systems
are similar, in that they both produce chemicals destined to hit up certain receptors, they
operate at very different speeds. It’s like, if the nervous system wants to get in touch
with you, it sends you a text. But if the endocrine system has a message, it will like
lick the stamp, and put it on, and write your address, and then a note and a pen on paper,
and then fold it up and put and mail it to you with the Post Office. But fast isn’t always
better, and your body will remember that letter longer than the text. Hormones, they linger.
Which helps explain why it takes some time to simmer down after a moment of severe fright
or anger. And our endocrine systems have a few important
hormone brewing glands. We’ve got a pair of adrenal glands snuggled up against our kidneys
that secrete adrenaline, that famous fight or flight hormone that jacks up your heart
rate, blood pressure and blood sugar, giving you that tidal wave of energy preparing you
to run like heck or punch that charging baboon in the throat; the pancreas sits right next
to the adrenal gland and oozes insulin and glucagon hormones that monitor how you absorb
sugar, your bodies main source of fuel. Your thyroid and parathyroid glands at the base
of your throat secrete hormones that regulate your metabolism and monitor your body’s calcium
levels; if you have testicles, they’re secreting your sex hormones like estrogen and testosterone,
and if you’ve got ovaries, they’re doing that job. And all those glands are super important,
but there is one gland that rules them all, and in the darkness binds them: the pituitary
gland. Although it’s just a little pea-sized nugget hidden deep in the bunker of the brain,
it is the most influential gland in this system. It releases a vital growth hormone that spurs
physical development and that love hormone, oxytocin, that promotes warm, fuzzy feelings
of trust and social bonding. What really makes the pituitary the master gland is that its
secretions boss around the other endocrine glands, but even the pituitary has a master
in the hypothalamus region of the brain, which we will talk more about next episode. So, AHHHHHHHHH! if I managed to scare you,
sorry, but I’m illustrating a point. You have no control over being scared, but maybe now
you do understand a little more clearly how your nervous and endocrine systems worked
together to call the shots. First, the sensory input from your eyes and
ears went to your brain, the simplest bits of your hypothalamus without even letting
you analyze it and were like ahhhh, and then, that ran down the chain of command from your
pituitary to your adrenal glands, to the hormone adrenaline, to the rest of your body and then
back to your brain, which then realized that I was just messing with you and told everybody
to just calm down for once! The whole deal is a feedback loop: your nervous
system directs your endocrine system which directs your nervous system, brain, gland,
hormone, brain. And of course each of these systems is fantastically complex. Way more
than we can get into here. So, in our next lesson, we’re gonna get all
up in your brain, and delve deeper into the different components of your nervous system,
find out what your old brain is, and learn about how much of your brain you actually
use. In the meantime, thank you for watching this
lesson in Crash Course Psychology which was brought to you by Zane Ice, who wants to say
hi to his friend Harrison. Thank you, Zane. If you’d like to sponsor an episode and give
your own shout-out, you can learn about that and other perks available to our subbable
subscribers, just go to subbable.com/crashcourse. This episode was written by Kathleen Yale,
edited by Blake de Pastino, and our consultant is Dr. Ranjit Bhagwat. Our director and editor
is Nicholas Jenkins, the script supervisor was Michael Aranda, who was also our sound
designer, and the graphics team is Thought Cafe.

100 thoughts on “The Chemical Mind: Crash Course Psychology #3

  1. On 7:52 there is an error: testes are producing testosterone, not estrogen/progesterone, this is a work for ovary as he told.

  2. I love that you said weeping angels like it's 100% plausible… I wish, because that means theirs a Doctor to travel with!

  3. Yes that's why their slower and have less emotive capabilities. Curly hair is just another thermal adaption… liars , normal is not sociopathic laziness

  4. I honestly am not scared, they kidnapped my children and are avoiding responsiblity. They ( pedophile kidnappers who claim Jewish lineage) need to pay

  5. do we gotta know all this four the exam? I wanna be a psycholgist but I don't wanna have to read stuff

  6. 50% speed and he litterally sounds drunk. It's the best thing ever, I should watch all of his videos like this. I guess all you need to be coherent and smart sounding is by sounding drunk and speed up your voice

  7. “Dear Hank,
    I think that you should maybe consider removing your hand from the burner, I mean, it doesn’t really feel good, you know what I mean? I love you.
    Love, endocrine system.”

  8. This is an amazing video to watch on LSD.

    Edit: Just got to 8:35. This is not an amazing video to watch on LSD.

  9. Over the past few years I've discovered I have an absolutely terrible "fight" response to sudden stimuli. Once, a friend grabbed my sides from behind unexpectedly and I turned around and pimp slapped her as hard as I could with 0 thought behind it.

    Another time, a friends cat got her tail stuck in the door and was freaking out and my friend came rushing at me so I threw her by the throat against the bookshelf. Again, 0 anger or thought behind what I was doing.

    It really makes me nervous! I was able to repair those relationships rather quickly but I worry what happens one day when an unforeseen situation causes something similar out in the "real world"? I could be slapped with assault charges or worse!

  10. How calm must I be if I didn't even budge @ 8:34? I literally didn't even budge. I have earphones on and volume is on full XD goddamn it.

  11. You do have control over if you are scared or not… scared is fear, but the control you can learn is how to react to the unexpected and that is the fight or flight response.

  12. I’ve just started my bachelor of counseling and these videos are helping me so much! I learn so much more from these then reading my psychology book.

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