WEBVTT

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Say it's late at night you're home alone

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Drifting off to sleep, entering that dream about Fritos and suddenly there's a banging on the door

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suddenly, you're wide awake and it feels like your heart is gonna explode, you jump up

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ready to run out the back door, possibly grab a Phillips head screwdriver and

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stabbed into the darkness until it sticks into something... now, whether it's a

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reaping angel or your neighbor looking to borrow a can of beans

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it doesn't really matter because when you heard that sudden noise

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your startled brain released an icy typhoon of chemicals and everything is 
now going through your mind like your

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urge to flee your urged to defend yourself that internal debate about

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whether weeping angels are even real... and... well, wheres the cat?

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all that, it's just the result of those chemicals. Our brains and our nervous systems and

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the substances they're producing are always bathed in, are amazingly complex

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nuanced systems even though we're always talking about her mental activity as

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being somehow separate from all the biological stuff going on in our bodies in reality

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the moods ideas impulses that flashed through our minds are spurred

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by our biological condition as psychologies like to say everything psychological is biological.

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So one way to understand how your mind

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works it's a look at how the chemistry in your body influences how you think

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sense and feel about the world around you.

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To do that, we begin at the simplest level, the system with the smallest parts

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it's all about the neuron, baby.

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Neurons or nerve cells are the building blocks that comprise our nervous systems.

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Neurons share the same basic makeup as our other cells but they have

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electrochemical mojo that lets them transmit messages to each other

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your brain alone is made up of billions of neurons and to understand why we think or dream, or do anything.

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You gotta first understand how these little transmitters work.

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There's actually several different types of neurons in your body from ones that are less than a millimeter long in your brain,

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to ones that run the whole length of your leg.

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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.

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I'm getting off-topic, sorry.

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No matter how big a nerve is, they all have the same three basic parts:

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The soma, dendrites and axon.

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The soma, or cell body, is basically the neurons' life support it contains all that necessary cell-action,

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like the nucleus, DNA, mitochondrial ribosomes and such.

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So, if the soma dies the whole neuron goes with it.

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The dendrites have bushy branch like the trees they're named after receive
messages,

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and gossip from other cells. Their listeners whispering what they hear back to the soma.

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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.

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The dendrites are short and bushy the axe on fiber is

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long and depending on what happened near on it is is sometimes encased in a protective layer a fatty tissue.

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Called myelin sheath. It's almost like an insulated electrical wire the myelin sheaths speeds up the transmissions of messages,

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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.

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Neurons transmit signals either whenstimulated by sensory input or triggered by neighboring neurons.

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The dendrites pick up the signal and activate the neurons action potential,

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or firing impulse. That shoots anelectrical charge down the axe onto its terminals.

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and toward the neighboring neurons the contact point between neurons are called synapses.

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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. 


NOTE Paragraph

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They're less than a million permanent apart,

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and that microscopic cleft is called the syntactic gap. So with an action potential runs down to the end of an axon

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it activates the chemical messengers that jump that tiny syntactic gap.

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Flying like that little air kiss and landing on the receptor sites of the receiving neuron.

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Both messengers are neuro transmitters. Although neuro transmitters slide right into their intended receptors.

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Like a key into a lock. They don't stay bonded to the receiving neurons. They just sort of pop out.

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Having excited or inhibited the receiving neurons trigger.

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Then the actors immediately get reabsorbed by the neuron that released them in the first place.

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In a process called re-uptake. Kinda like, here you go. Oh, psyche!

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So neurons communicate with neuro transmitters. Which in turn cause motion and emotion.

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They help us move around make jazz hands, learn, feel, remember, stay alert, get sleepy .

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And pretty much do everything we do. Some of them just make you feel good.

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Like the endorphins we get floodedwith after running 10 miles,

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or falling in love, or eating a really good piece of pie.

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We got over a hundred different kinds of these brilliant neuro transmitters.

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Some are excitatory and others are inhibitory ,and all are good reminders that everythingpsychological is also biological.

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Excitatory neurotransmitters rev up the neuron increasing the the chances it will fire off an action potential.

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Nora Ephron's is probably familiar with that help control alertness and arousal.

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Glutamate is another involved in memory but and oversupply of it can wig out the brain,

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and cause seizures and migraines. Which is why some people are sensitive to all that MSG or mono sodium glutamate, and the rhyme.

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Inhibitory neurotransmitters on the other hand chill neurons out decreasing the
likelihood that the neuronal jump into action.

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Gaba, gamma- amino butyric acid is a major inhibitory neurotransmitter,

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and you probably heard of serotonin which affects your mood in hunger, and sleep.

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Low amounts of serotonin are linked to depression and certain class of antidepressants help raise serotonin levels in the brain.

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Some neurotransmitters like acetylcholine and dopamine play both sides, and can both excite,

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or inhibit neurons depending on what type of percept as they encounter.

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Acetylcholine enables muscle action influences learning and memory.

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Alzheimer's patient experience and deterioration of their acetylcholine in producing neurons.

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Dopamine meanwhile is associated with learning movement in pleasurable emotions,

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and excessive amounts of it are linked to schizophrenia as well as addictive and impulsive behavior.

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So neuro transmitters are basically you nervous systems carriers,

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but they aren't the only chemical messengers delivering the new they've got some competition brewing.

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In the endocrine system and if you've been through puberty you know what I'm talking about.

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Hormones. Like neurotransmitters hormones act on the brain and indeed some of them are chemically identical to certain neurotransmitters.

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Hormones affect our moods, arousal, and circadian rhythm. They regulate metabolism monitor our immune system, signal growth,

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and help with sexual reproduction.

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You can say that most of them boil down to the basics: attraction, appetite, and aggression.

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Whereas neurons and synapses flick on and off sending messages with amazing speed.

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The endocrine system like to take its time delivering the body slow chemical communications through a set of glands that secrete hormones,

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into the bloodstream. Where their ferried to other tissues especially the brain.

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So well the nervous and endocrine systems are similar in that they both produce chemicals destined to hit upcertain receptors.

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they operate at very different speeds is like and the nervous system one think it undoubtedly

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would send you a text but if the
endocrine system and the message

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it will like lick the stamp and put it
on right you're dressed in a note in a

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pan on paper and then fold it up and put in mail it to you within post office slip past

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isn't always better and your body will
remember that letter longer than the

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text or loans

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they linger which helps explain why it
take some time to simmer down after a

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moment that severe freighter anger and
endocrine systems have

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a few important hormone brewing Lanza
got a pair the adrenal gland snuggle up

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against her kidneys that secrete
adrenaline that famous fight or flight

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hormones and Jack Sep your heart rate
blood pressure and blood sugar

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given you that tidal wave energy
preparing in a run like hecker

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punch that charging baboon in the throat
the pancreas it's right next to the

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adrenal gland and loses

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insulin and glucagon hormones that
monitor how you absorb sugar

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your body's main source of fuel to fire
on in parathyroid glands the base your

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throat secrete hormones that regulate
your metabolism and monitor your body's

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calcium levels to be at st. go there's a
greeting your sex hormones like estrogen

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and testosterone to get ovaries they're
doing that job and all other super

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important but there is one bland

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and rules them all and in the darkness
bind them not

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the pituitary gland how long does a
little P fis not it hidden deep in the

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bunker in the brain

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it is the most influential gland in this
system and releases a vital growth

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hormone that spurs physical development

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and that love the hormone oxy 2007 that
promote warm fuzzy feelings have trust

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in social bonding what really makes the
pituitary the master gland is that it's

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secretions boss around the other in the
green glands

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but even the pituitary as a master and I
both elements region of the brain which

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we will talk more about next episode sup

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cable managed to scare you sorry but I'm
illustrating a point

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you have no control over being scared
but maybe now you do understand a little

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more clearly

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how you're nervous and endocrine systems
work together to call the shots

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first the sensory input from your eyes
and ears went to your brain

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the simplest been severe I've alan is
without even making you analyze it more

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likely why

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and then that ran down the chain of
command from your pituitary to your

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adrenal glands the hormone adrenaline

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the restive your body and then back to
your brain which

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then realize that I was just messing
with you and told everybody to just calm

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down for wants a whole deal

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is a feedback loop your nervous system
director endocrine system which directs

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you nervous system brain gland hormone
brain and of course

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into these systems is fantastically
complex way more than we can get into

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here

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cell in our next lesson we're gonna get
all up in your brain

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and delve deeper into the different
components and your nervous system find

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out what your

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old brain is and learn about how much in
your brain

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you actually use meantime thank you for
watching his lesson in crash course

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ecology which was brought to you

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by Zane ice who wants to say hi to his
friend Harrison

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thanking sane if you like to sponsor
numbers only give your own shoutout

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you can learn about that and other perks
available to our sobel subscribers

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just go to Stumble dot com slash crash
courses episode was written by kathleen

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yell edited by blinking bestie know and
our consultant is doctor run G Dawg what

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our director and editor is Nicholas
Jenkins the script supervisor was

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Michael Aranda

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was also our sound designer and the
graphics team is like affect