Say it's late at night you're home alone
Drifting off to sleep, entering that dream about Fritos and suddenly there's a banging on the door
suddenly, you're wide awake and it feels like your heart is gonna explode, you jump up
ready to run out the back door, possibly grab a Phillips head screwdriver and
stabbed into the darkness until it sticks into something... now, whether it's a
reaping 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 is now going through your mind like your
urge to flee your urged to defend yourself that internal debate about
whether weeping angels are even real... and... well, wheres the cat?
all that, it's just the result of those chemicals. Our brains and our nervous systems and
the substances they're producing are always bathed in, are amazingly complex
nuanced systems even though we're always talking about her mental activity as
being somehow separate from all the biological stuff going on in our bodies in reality
the moods ideas impulses that flashed through our minds are spurred
by our biological condition as psychologies like to say everything psychological is biological.
So one way to understand how your mind
works it's a look at how the chemistry in 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.
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.
There's actually 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 150 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 neurons' life support it contains all that necessary cell-action,
like the nucleus, DNA, mitochondrial ribosomes and such.
So, if the soma dies the whole neuron goes with it.
The dendrites have bushy branch like the trees they're named after receive messages,
and gossip from other cells. Their listeners whispering what they hear back to the soma.
The Axon, is the talker and this long cable like extension transmits electrical impulses from the cell body out to other neurons, or glams or muscles.
The dendrites are short and bushy the axe on fiber is
long and depending on what happened near on it is is sometimes encased in a protective layer a fatty tissue.
Called myelin sheath. It's almost like an insulated electrical wire the myelin sheaths speeds up the transmissions of messages,
and the grades 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 whenstimulated by sensory input or triggered by neighboring neurons.
The dendrites pick up the signal and activate the neurons action potential,
or firing impulse. That shoots anelectrical charge down the axe onto its terminals.
and toward the neighboring neurons the contact point between neurons are called synapses.
All those bushy little dendrites are decorated with synapse is that almost but don't quite tut the neighboring axon in the tiniest game, of I'm not touching of all time.
They're less than a million permanent apart,
and that microscopic cleft is called the syntactic gap. So with an action potential runs down to the end of an axon
it activates the chemical messengers that jump that tiny syntactic gap.
Flying like that little air kiss and landing on the receptor sites of the receiving neuron.
Both messengers are neuro transmitters. Although neuro transmitters slide right into their intended receptors.
Like a key into a lock. They don't stay bonded to the receiving neurons. They just sort of pop out.
Having excited or inhibited the receiving neurons trigger.
Then the actors immediately get reabsorbed by the neuron that released them in the first place.
In a process called re-uptake. Kinda like, here you go. Oh, psyche!
So neurons communicate with neuro transmitters. 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 floodedwith after running 10 miles,
or falling in love, or eating a really good piece of pie.
We got over a hundred different kinds of these brilliant neuro transmitters.
Some are excitatory and others are inhibitory ,and all are good reminders that everythingpsychological is also biological.
Excitatory neurotransmitters rev up the neuron increasing the the chances it will fire off an action potential.
Nora Ephron's is probably familiar with that help control alertness and arousal.
Glutamate is another involved in memory but and oversupply of it can wig out the brain,
and cause seizures and migraines. Which is why some people are sensitive to all that MSG or mono sodium glutamate, and the rhyme.
Inhibitory neurotransmitters on the other hand chill neurons out decreasing the likelihood that the neuronal jump into action.
Gaba, gamma- amino butyric acid is a major inhibitory neurotransmitter,
and you probably heard of serotonin which affects your mood in hunger, and sleep.
Low amounts of serotonin are linked to depression and 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 percept as they encounter.
Acetylcholine enables muscle action influences learning and memory.
Alzheimer's patient experience and deterioration of their acetylcholine in producing neurons.
Dopamine meanwhile is associated with learning movement in pleasurable emotions,
and excessive amounts of it are linked to schizophrenia as well as addictive and impulsive behavior.
So neuro transmitters are basically you nervous systems carriers,
but they aren't the only chemical messengers delivering the new 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 metabolism monitor our immune system, signal growth,
and help with sexual reproduction.
You can 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 like to take its time delivering the body slow chemical communications through a set of glands that secrete hormones,
into the bloodstream. Where their ferried to other tissues especially the brain.
So well the nervous and endocrine systems are similar in that they both produce chemicals destined to hit upcertain receptors.
they operate at very different speeds is like and the nervous system one think it undoubtedly
would send you a text but if the endocrine system and the message
it will like lick the stamp and put it on right you're dressed in a note in a
pan on paper and then fold it up and put in mail it to you within post office slip past
isn't always better and your body will remember that letter longer than the
text or loans
they linger which helps explain why it take some time to simmer down after a
moment that severe freighter anger and endocrine systems have
a few important hormone brewing Lanza got a pair the adrenal gland snuggle up
against her kidneys that secrete adrenaline that famous fight or flight
hormones and Jack Sep your heart rate blood pressure and blood sugar
given you that tidal wave energy preparing in a run like hecker
punch that charging baboon in the throat the pancreas it's right next to the
adrenal gland and loses
insulin and glucagon hormones that monitor how you absorb sugar
your body's main source of fuel to fire on in parathyroid glands the base your
throat secrete hormones that regulate your metabolism and monitor your body's
calcium levels to be at st. go there's a greeting your sex hormones like estrogen
and testosterone to get ovaries they're doing that job and all other super
important but there is one bland
and rules them all and in the darkness bind them not
the pituitary gland how long does a little P fis not it hidden deep in the
bunker in the brain
it is the most influential gland in this system and releases a vital growth
hormone that spurs physical development
and that love the hormone oxy 2007 that promote warm fuzzy feelings have trust
in social bonding what really makes the pituitary the master gland is that it's
secretions boss around the other in the green glands
but even the pituitary as a master and I both elements region of the brain which
we will talk more about next episode sup
cable 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 you're nervous and endocrine systems work together to call the shots
first the sensory input from your eyes and ears went to your brain
the simplest been severe I've alan is without even making you analyze it more
likely why
and then that ran down the chain of command from your pituitary to your
adrenal glands the hormone adrenaline
the restive your body and then back to your brain which
then realize that I was just messing with you and told everybody to just calm
down for wants a whole deal
is a feedback loop your nervous system director endocrine system which directs
you nervous system brain gland hormone brain and of course
into these systems is fantastically complex way more than we can get into
here
cell in our next lesson we're gonna get all up in your brain
and delve deeper into the different components and your nervous system find
out what your
old brain is and learn about how much in your brain
you actually use meantime thank you for watching his lesson in crash course
ecology which was brought to you
by Zane ice who wants to say hi to his friend Harrison
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just go to Stumble dot com slash crash courses episode was written by kathleen
yell edited by blinking bestie know and our consultant is doctor run G Dawg what
our director and editor is Nicholas Jenkins the script supervisor was
Michael Aranda
was also our sound designer and the graphics team is like affect