The Chemical Mind - Crash Course Psychology #3 Video Lecture | Psychology Fundamentals: Learning Made Easy - Self Help Learning

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
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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.