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00:02
I think that we have begun the livestream
now.
00:08
I'm Hank Green, this is Office Hours.
00:10
I was once the host of Crash
Course Anatomy & Physiology.
00:13
And for the next hour, we're going to
be answering your questions about A&P
00:16
to maybe help you study for
finals or whatever you're up to.
00:20
And I'm joined by a person who actually knows
stuff about anatomy and physiology, our script,
00:24
our consultant on that project who helped
us make sure we got everything right.
00:28
Hello, Brandon Jackson.
00:34
>Brandon, tell us a little bit
about who you are, what you do.
00:36
<I'm now an associate professor
at Longwood University.
00:40
I've been here for about seven years.
00:43
I used to live in Missoula where we
first met and, I was thinking about it,
00:45
I've taught Anatomy & Physiology
or Comparative Anatomy
00:49
for almost 18 years now.
So it's been quite a ride.
00:52
>That's great. Well, you're
the right person to have here.
00:56
Here's how it's going to go,
00:59
we've got people to send in
their questions ahead of time
01:00
so we've got some prepared
that we know we're going to do.
01:03
Then we're going to talk a little bit about some
01:06
study tips for specifically how
to study for Anatomy & Physiology,
01:07
which I found very helpful
learning about from Brandon.
01:10
And then we're going to end with
some questions from the chat.
01:13
So if you have any, put them in there,
01:16
appreciate all of you for doing that.
01:17
Before we get to your questions, I want to
01:20
talk a little bit about our
partner for Office Hours.
01:21
We're very lucky to have a partner.
01:24
It's Flipgrid, which is a free video discussion
app from Microsoft, and they got a mission
01:25
to make learning fun and empowering for all.
01:31
It's been used in the classroom for nearly
a decade and as we talk about preparing for
01:33
exams, Flipgrid is a convenient way to host
study groups so that having to coordinate
01:39
around a class schedule or
after-school commitments.
01:43
You can create a group, start a topic and
send the link to anyone you want to join.
01:46
You can record video or audio responses,
discuss specific in detail, quiz each other,
01:51
prep for group presentations, all of that.
01:56
We hear from Crash Course viewers all the
time, how helpful video is as a learning tool,
01:59
it's one of the reasons we made Crash Course
and connecting with peers and learning in
02:04
groups with your peers in a community is a
wonderful thing.
02:08
We use Flipgrid to collect some of the questions
that we're going to be asking on the livestream.
02:11
So let's start with some questions for the
livestream.
02:14
Brandon, are you ready?
02:18
Do you know enough about Anatomy & Physiology
to answer these questions?
02:19
<I will do my best.
02:24
>I'm pretty sure you do.
02:25
This first one comes from Drew who asks is
the heart a muscle or an organ?
02:27
This is great, because now we get to talk
about muscles, organs, tissue, cells.
02:33
<Exactly. This is a really interesting question.
02:37
It seems kind of simple at first, and it's
not just a yes or no answer, this is going
02:39
to be kind of a long-winded answer unfortunately
I think, but it's kind of cool.
02:44
But really we have to get down to definitions
and the hierarchy of organizations that we
02:49
talk about in Anatomy & Physiology,
02:54
and most of Biology
really, right?
02:57
So we can take atoms and make molecules, we
can take molecules and if we arrange them
02:58
in just the right way, we get cells.
03:02
If we take a bunch of cells that all look
alike and function together and organize them
03:05
in the right way in a body, that's what we
call a tissue.
03:10
And this is where we kind of start.
03:13
Now, if we take multiple tissues and combine
them together, and we get a thing in the body,
03:15
a structure in the body that has more or less
03:20
a single function, or
sometimes multiple functions,
03:23
So an organ has multiple tissues and at least
one obvious function.
03:27
>Now, see, I think this is what confused me
about this and maybe what is confusing Drew
03:32
about this is that I hear that muscle is a
tissue type?
03:38
>But /a/ muscle is not a tissue type?
03:45
<You got it. You got it.
03:50
So muscle is a tissue type.
03:52
It's one of four tissue types.
03:54
So we have epithelial tissue, muscle tissue,
nervous tissue, and connective tissue.
03:56
>I mean, I love that there's only four, that's
way easier than almost everything.
04:01
<How many episodes did we do on tissue?
04:06
I think we did two on just connective tissue
because there's, I don't know, 14 kinds of
04:08
whatever, not counting here.
04:13
So of muscle tissue, there's actually three
kinds of muscle tissue and you can tell the
04:16
difference if you look just
down at the cellular level
04:21
and then there's some other
functional differences.
04:23
But really the ones we're talking about here,
there's two, there's skeletal muscle tissue,
04:25
and that's muscle, the tissue you find in
your favorite skeletal muscle.
04:30
Hank, what's your favorite skeletal muscle?
04:34
>My favorite skeletal muscle has got to be
the butt, right?
04:36
So the gluteus maximus, that one.
04:40
Yeah, we'll call it the gluteus maximus.
04:43
There's a medias too, there's some other muscles
in there.
04:45
So the gluteus maximus, now that is a skeletal
muscle that has skeletal muscle tissue in
04:48
it, as opposed to the heart, which has cardiac
muscle tissue in it.
04:52
So those are multiple muscle tissue types.
04:56
Now are they an organ?
05:01
And this is kind of the other part of the
question.
05:03
So let's take the gluteus maximus first.
05:05
And is that an organ?
05:07
It actually is, because remember the definition
of an organ is multiple tissue types.
05:10
So we have the skeletal muscle tissue in there
and that's the bulk of it, that's the thing
05:14
that does the work.
05:18
>Does the work, but you can't do the work,
let me see if I can name a couple others.
05:19
I can feel my butt so it's got nervous tissue
in it and my butt is alive so it's got to
05:23
have some vasculature, there's got to be some
delivery of oxygen so it's got veins and stuff.
05:28
<So it's got veins and stuff, so arteries and
veins going through there.
05:33
And those are actually lined with simple squamous
epithelial tissue called-
05:36
>Epithelial tissue.
05:41
<So that's your epithelial.
05:42
So we actually have all four tissue types
in the muscle.
05:44
We didn't talk about connective tissue in
there, but you have the tendons connected
05:47
to the end, that's connective tissue, dense
connective tissue.
05:52
And then kind of through the rest of the muscle,
we have all these different layers, like the
05:56
epimysium and the perimysium and those are
also connective tissue.
06:00
So there's your organ, all four tissue types.
06:05
It's kind of an overachiever of an organ.
06:08
.But you don't really think of it that way.
06:13
Because I'm like, yeah, a liver is an organ
when I can take out and hold it in my hand
06:14
and be like, "That looks like an organ."
06:18
So now you say, how many organs do you have
in your body?
06:21
And now you have to add in all the muscles
on top of the things you usually think about
06:23
Okay, well, that's skeletal muscle, but what
about cardiac muscle?
06:30
Same thing, add up the tissue types.
06:34
What we have there, cardio muscle cells, that's
the cardiac muscle tissue so that's one.
06:35
We also have epithelium, the inside of the
heart is the endocardium, the outside of the
06:42
heart is the epicardium.
06:48
Those are both epithelial tissues.
06:50
And then there's other forms of connective
tissue in and around it, there's fat tissue
06:54
around it that's connective.
07:00
The valves inside of the heart are a type
of connective tissue.
07:01
>Yeah, I've never touched one, but I've seen
them and they look like cartilage almost.
07:04
Yeah they're kind of leathery I guess you
could say.
07:13
So there we have multiple tissue types, an
obvious function like pumping the blood.
07:18
There we go, it's an organ.
07:23
So here's the question.
07:25
<It's muscle-y.
>That's my answer for you.
07:32
<Right, so in Anatomy & Physiology, we have very
specific language.
07:37
So we don't just say "a muscle," we say a
07:42
So is it a skeletal muscle? No.
07:45
>No.
<Is it muscular?
07:49
Is it a muscle in kind common day, everyday
language?
07:51
Sure, it's a muscle,
07:54
but definitely it's an organ
and skeletal muscles are also organs.
07:56
>Skeletal muscles are organs,
just blown everybody's
08:01
Okay, got another question for you.
08:04
This one came in from Flipgrid and Maggie
asks, "I'm in my first year of college, my
08:07
first year taking anatomy.
08:11
I had a question about skin cells.
08:13
How are they organized throughout the layers
of the skin?"
08:15
So she goes on talk about a bunch of different
types of skin cells and are they like, spread out?
08:18
So you've got melanocytes,
you've got keratinocytes,
08:24
Langerhans cells, which
are, I think, immune cells.
08:27
Am I wrong about that?
08:31
<Nope, that's correct.
08:32
>And so they're in the skin.
08:34
Are they peppered throughout?
08:35
Are they in layers?
08:37
As the skin, like, it sort of builds up
at the bottom and then pushes higher,
08:39
do these things move up with it
or do they stay in the same place?
08:44
How are they doing this?
08:47
What are they doing?
08:48
<Yeah, so some of these cells are related to other
and some aren't and so we can start with that.
08:50
And actually, the idea of the tissues will
come back into play here.
08:58
So the main cell that we talk about with the
epidermis at least are the keratinocytes,
09:02
these are what make the keratin that make
your skin kind of dry and tough and yeah,
09:08
they do the job they say.
09:15
>Impermeable, yeah.
09:16
And so these are formed in the stratum basale,
the deepest layer of the epidermis.
09:18
And that's where the new ones are formed from
a thin layer of stem cells.
09:24
So the stem cell divides,
it creates one keratinocyte
09:28
and then the other one is still going to stay
09:31
down there as the stem cell.
09:34
And so that keratinocyte then gets kind of
pushed higher and higher as new, younger ones
09:36
are made behind it.
09:42
And I mean, it's kind of dark to think about
this, but these skin cells are almost like
09:43
us says we age, right?
09:47
We start up young and plump and happy and
healthy and then as we age,
09:49
we start getting some spots and that bit-
09:54
>Harder. Life happens.
<Just the stratum moves them.
09:57
That's the stratum spinosum.
10:00
Yeah, you get beat up, withered, dried up, you
end up literally a shell of your former self.
10:03
And at that point -- if you're keratinocyte,
10:09
at least -- you're dead
and you're just the keratin
10:11
and wax that you kind of aged with.
10:14
And then you're in the stratum corneum, the
top layer.
10:17
Eventually, you get pushed off
at lost as dust, basically.
10:20
> Yes. Which is all of our
eventual fates, just lost as dust.
10:24
<Just lost as dust.
10:29
So, okay, it's a very dark analogy, but so
that one cell once you're kind of born as
10:30
a keratinocyte, you're always a keratinocyte.
10:41
Now we have these other cells, the melanocytes,
these are the cells that provide the various
10:44
hues of brown to our skins.
10:50
And melanocytes are actually
related to the keratinocyte.
10:53
So the keratinocytes are an epithelial cell,
stratified squamous epithelial cell, and the
10:56
melanocytes are also epithelial.
11:01
They are kind of distant
cousins of the keratinocytes.
11:04
So the melanocytes come from a different stem
cell, but the keratinocyte stem cell and the
11:08
melanocytes stem cell come
from the same stem cell.
11:12
>It's like a taxonomic tree happening here,
but just our body cells.
11:16
<Yeah. It's like cousins, right?
11:20
They share a grandfather or grandparents,
something like that.
11:23
And so the melanocytes, that stem cell is
usually found near hair follicles, but then
11:27
the melanocyte kind of migrates through, sets
up shop in the lower levels of the keratinocyte
11:32
and with the younger ones and creates melanin
and then kind of distributes that melanin
11:39
further up in the skin.
11:45
And they can be much longer lived.
11:46
> So it never moves up, it just sort of like hangs
out there and they move past it?
11:48
The cells kind of move past and pick up these
melanin granules and carry them up and then
11:53
lose them eventually.
12:00
Let's see.
Where were we?
12:03
So then that's the melanocyte, that's kind
of a cousin, still epithelial.
12:04
And then we had the Langerhans cell and the
Langerhans, like you said, is an immune cell.
12:08
And so the immune cells are actually essentially
blood cells, right?
12:14
We've heard of white blood cells.
12:20
>Totally different cell lineage, not the same
stem cells.
12:21
<Totally different.
12:24
That's connective tissue, blood is actually
connective tissue.
12:25
And these forms-
>You say this, it will never make sense to me.
12:28
What's blood connect to?
We don't have to talk about it.
12:31
<Everything? No-- [laughs]
12:34
I mean, it's-
>I don't think that's what they meant when
12:36
they originally came up with the term connective
tissue that connects skeletal stuff together.
12:39
But hey.
<It is kind of a grabble.
12:44
There's some embryology that supports blood
12:47
in this group and we won't
get into that right now.
12:49
<So these are immune cells.
12:53
They're actually monocytes, one of the five
white blood cells or leukocytes that are floating
12:55
around in your body.
12:59
These are monocytes and monocytes are famous
for crawling out into different parts of the
13:00
body and depending on where they are, we give
them a different name, but really they always
13:04
become a macrophage.
13:08
So at these Langerhans cells are also called
dendritic cells because they have lots of
13:10
branches and dendrite means branches.
13:15
But really they are a macrophage.
13:19
So macrophage is this big functional description.
>Like white blood cells, yeah.
13:22
<And so they're the big thing that goes out
and gobbles up all of the bacteria that are
13:25
trying to get through their skin.
13:29
That's what they're doing there.
>Yeah.
13:30
<And they're free-floating, they're not attached
so they can move around a little bit, mostly
13:33
really found down in the dermis, in the top
of the dermis right underneath the epidermis,
13:38
but they can be found elsewhere.
13:44
>Right, right. And so they're staying there,
they're not moving up with everything?
13:47
<No, they're also not getting moved up.
13:51
>So it's just, like, there's like
the conveyor belt of keratinocytes,
13:52
but nothing else goes up the conveyor belt?
13:55
And then the last one are the Merkel discs,
or the Merkel cells, and they're really nervous
13:59
function, they're part of our sensory system,
they're part of how we sense touch and one
14:06
of the types of touch.
14:11
And as far as I can tell, we don't actually
know exactly what they come from in terms
14:13
of their stem cell lineage.
14:19
They function with the nervous system, some
people say from what I've read, they say that
14:21
they come from skin cells or they say that they
come from the nervous system.
14:26
It's actually kind of cool because both the
skin and the nervous system come from the
14:30
ectoderm embryological, so they're at least
distant cousins in that manner.
14:34
> So they're all friends
and they hang out together,
14:42
but only there's only one conveyor belt and
14:47
it's keratinocytes?
14:49
>Alright, we have another question.
14:52
We have got a bunch of people who ask questions
about the nervous system and gated channels
14:54
and action potentials.
15:00
Kit and Diana and Allie and Allen and Wazi.
15:02
So can you tell me just in general about ion
channels, I guess, and action potentials.
15:06
<This is about maybe two chapters in even an
introductory book.
15:15
But it's actually really interesting because
if you get down the basics, and I'll try to
15:21
boil this down to just a few rules here, but
if you can get the basics down, you actually
15:25
learn about not just how neurons work, but
15:30
also how the heart works,
how skeletal muscle works.
15:32
There's probably something else that uses
these action potentials that I can't think
15:36
>Well, I mean any sensing.
15:40
<Exactly, all of our senses.
15:43
Our eyes, our ears.
15:44
And this is also a very common stumbling block
for students.
15:48
A lot of people have trouble when they're
starting out learning this so I like to teach
15:52
this boiled down to just a few pretty simple
rules.
15:56
It's oversimplifying a little bit, but if
you get these down, then you can add on the
16:01
other layers that really help you get into
all the details.
16:06
Okay, so first rule, there are more sodium
ions outside of these cells than inside and
16:10
there's more potassium inside than outside.
16:17
And the cell is making that happen?
16:21
The cell is making happen with a pump called
the sodium-potassium pump.
16:23
So good name for it.
16:28
>Pump the potassium in, sodium out?
16:29
So rule one, sodium's out, potassium's in.
16:31
And both of them are positive ions if you
don't know that.
16:35
Okay, now these kinds of ions, when they're
dissolved in water, we call them solutes and
16:39
generally, solutes want to move from areas
16:45
of high concentration to
areas of low concentration.
16:48
In other words, given the opportunity, sodium
wants to come into the cell because it's outside
16:53
and potassium wants to get out of the cell
because it's inside.
16:59
>We got that.
<Okay.
17:05
Rule three, don't worry too much yet about
exactly how we got here but if we were to
17:07
measure the electrical difference, remember
17:14
these are electrically
charged, they're both positive.
17:16
If we were to measure the electricity inside
of the cell compared to the outside, it would
17:19
show up at about -70.
17:23
And depending on the book, sometimes it's
listed as -65, -70, close enough.
17:25
>Who cares?
<Yeah, it's close enough.
17:29
>Significant figures,
17:31
but why is there an electrical
charge if they're both positive charged?
17:34
<Oh, okay. So you want to ask about this?
17:38
>Well, it seems like a logical question to ask.
<It is.
17:41
So one reason is that inside of the cell,
17:44
there are large anionic
negatively charged proteins.
17:46
So there's some stuff inside of the cell that
has a negative charge that can't leave the cell.
17:51
There's another reason that has to do with
potassium trying to get out and actually being
17:57
allowed out a little bit down its gradient
and -70 is the balancing voltage to
18:03
prevent more from leaving.
18:08
>Yeah, the cell figured it out.
18:10
The cell made it so that there's
-70 milliwatts or whatever.
18:12
<Right. And this is the trick.
18:18
If the book tries to get you to see why it's -70,
leave that for later. You'll get it later.
18:20
It's so much easier if you leave that for
that after we talk about all the movement.
18:29
Okay, so we have -70, and then you
often see these graphs of action potentials
18:34
where you see a line, the voltage starting
at -70, and then it's going to go
18:40
up or down or something like that.
18:45
So it always will start at -70 or -65.
18:47
And that is again always telling you the inside
of the cell relative to the outside.
18:51
Okay, the last rule is actually a result of
all of those other rules.
18:58
And so here's, Hank, where I'm going to ask
you to answer this.
19:03
If the inside is -70 and sodium is
allowed to come into the cell,
19:07
and sodium's positively charged,
what happens to the voltage?
19:13
Does it go up or down?
19:16
Does it get more positive or-
>It goes up.
19:19
<Yeah, it goes up, it becomes
more positive or less negative.
19:20
>Less negative.
<Yeah, right.
19:24
So we're adding positives to the inside if
sodium comes in.
19:26
Now, what happens if potassium is allowed
to leave?
19:28
>Then it gets more negative.
19:32
<More negative, it goes down.
19:34
That's all the math you really need for this.
19:37
>Okay. Love that, up and down.
It's not math, it's just a direction.
19:39
<So sodium comes in and the line goes up, or
potassium goes out, the voltage goes down.
19:42
There are your rules.
19:50
If you get those, then the rest is literally-
19:51
>Just how everything works.
<just opening and closing doors and putting it in.
19:54
>And there's a bunch of different doors that
19:58
let the different things in
and out in different ways.
19:59
<Right. So really we can talk about four kinds of
doors and for right now we'll skip the first
20:01
two, I'll just mention them.
20:06
One is called the leakage channel.
20:08
So these are protein channels.
20:09
>Just a door?
<Yeah, it's an open door.
20:12
These are protein channels
across the cell membrane.
20:13
They're specific, they only let either sodium
or potassium through.
20:16
And so those things are going to go the direction
that they want to go.
20:20
And the leakage channels are just always open.
20:25
The other one that is part of how we sense
touch and hear and balance is called a
20:29
mechanically-gated channel.
20:34
Basically, it opens if the cell membrane gets
stretched, like the door gets stretched open.
20:35
>It's actually a physical reaction.
20:40
So when we are feeling
touch, we are feeling touch.
20:43
<Okay. So then we have two
other channels and they're
20:47
important for really what this question is
20:49
getting out of how neurons work.
20:51
One is called a chemically gated channel or
a ligand-gated channel.
20:53
And a ligand is just something that binds
to a protein.
20:58
This is a key in a lock kind of situation.
21:02
So here's a door it's closed, it's locked,
we need a key to open it.
21:05
That key is usually going to be something
like acetylcholine, which is a neurotransmitter,
21:09
it's actually the neurotransmitter that helps
trigger your muscles to contract.
21:14
Okay, so acetylcholine, if it binds to that
little protein, it's the key, it unlocks the door.
21:19
The one we usually talk
about with these ligand-gated
21:24
channels are sodium channels.
21:27
So let's say we open a sodium channel, what
happens to sodium?
21:29
Which direction does it go?
21:32
<Sodium's outside and it wants to come in.
21:38
>Wants to come in, okay.
21:40
<Yep. It wants to come in.
21:41
And so then the sodium right, now since we're
adding positives, the inside is going to get
21:42
more positive and the voltage is going to
start to go up.
21:47
Now we could-
>We should have just renamed these ions.
21:50
We should have called one of them the out
ion and one of them the in ion and that would've
21:55
simplified things greatly.
22:00
<Well, and the abbreviation for sodium is Na
and the abbreviation for potassium is K.
22:01
>So we picked the hardest to remember ones?
22:06
<I know, I know exactly.
22:08
>It's like mercury is a little bit harder than
those, but basically everything else.
22:10
<I'm glad I'm not responsible for the naming
convention.
22:16
So let's see.
So we have these key channels.
22:21
We can open sodium ones,
we can open potassium ones.
22:25
Now, the next ones are the important part for
how the action potential actually travels.
22:27
So the whole idea of this is to get a signal,
to go from point A like your brain to point B,
22:32
like your gluteus maximus muscle, and to
get it to contract.
22:37
Now that's a long way for it to travel and
so we want it to travel fairly quickly so
22:41
that we can react to proper things like walking,
22:45
it's important to time things
well when we're walking.
22:49
And that's what this next channel is, called
voltage-gated channels.
22:52
And they open when that voltage inside of
the cell reaches a certain level and just
22:56
in one location where that cell is.
23:01
So they open at about -55 millivolts.
23:04
We call this the threshold voltage for these
channels.
23:08
So we started at -70, right?
23:11
We bring in some sodium and then the line
starts to go up.
23:13
If that cell reaches about -55, the
voltage-gated channels will open.
23:16
And the first ones that open are the sodium
channels.
23:22
Did you have a question, Hank?
23:27
>No, I was just imagining them expanding.
23:29
<Yeah, so they open up,
23:31
sodium starts coming in now
these voltage-gated channels.
23:33
And as the sodium comes in, it starts to crawl
along the inside of the membrane.
23:35
It kind of floats in and then distributes.
23:40
And it's going to slide its way down to a
little bit further on down the cell, eventually
23:42
it will find another voltage-gated sodium
channel.
23:49
If enough sodiums are on the inside, it raises
the voltage.
23:52
At that point, opens that door, sodium marshes
in, slides down, next gate-
23:55
>Cascade.
<Sodium in, slides down.
24:00
And now we get this wave of sodium rushing
in all the way down the cell in a fraction
24:01
of a second, it can go a meter down your leg.
24:07
So very fast reaction.
24:11
>And this is why I like salt.
24:13
<This is why salt and sodium level is very
important.
24:15
Yeah, if you get too much or too little sodium
you get tingles and dizziness because your
24:19
muscles and your neurons can start to malfunction.
24:25
Now, when that gets all the way down to the
end of the neuron, it does something else,
24:29
it actually opens a voltage gate calcium channel
and calcium is just the fine signal that tells
24:33
the cell to release its neurotransmitters.
24:39
Now the whole time that this has been happening,
there's actually another channel, another
24:44
voltage-gated channel.
24:48
We kind of ignored potassium to this point, right?
24:49
And so the sodium at that threshold voltage
that was opening the voltage-gated sodium
24:52
channels was also opening voltage-gated potassium
channels, but they are sticky doors.
24:58
They don't open that quickly.
25:03
So actually they're like big, thick, creaky
doors, they're slowly opening, sodium's rushing
25:05
And by the time sodium's pretty much done
rushing in, potassium wants to rush out.
25:12
And so they're just offset enough.
25:18
So as the sodium rushes in, the voltage goes
up and right at the top at about +30
25:20
then the potassium channels start to open.
25:27
And then when the potassium channels open,
potassium is leaving.
25:30
So what happens if we take a bunch of positive
things from inside and we let them out, what
25:33
happens to the inside?
25:38
Does it get more positive or more negative
if we remove positives?
25:41
>I was looking at the Slack I
wasn't paying attention to you.
25:44
I had to check on something.
25:47
<It gets more negative.
Haha it's okay, my students text in class.
25:48
So the inside of the cell is going to get
25:57
more negative if those positive
potassiums are leaving.
25:59
And it actually is going to get so negative
that we reset the voltage.
26:05
So now we've sent the signal and we've reset it.
26:11
And again, there's a little bit more to it
than that, but if you can get that part down
26:15
and those rules that we started with, then
26:20
you can layer on the rest of
your understanding on that.
26:24
>Right, right, right.
Amazing.
26:27
I mean, and this is all, the great thing about
understanding that stuff is that from now
26:29
on and forever, you just have a totally different
understanding of how your body interacts with
26:34
the world around it.
26:38
<Yeah, yeah.
>It's pretty cool.
26:40
#9 is the question that this is on my
list, but not the number that we're on.
26:42
It's from Laurel who asks, what is the best
way to remember the names and locations of
26:50
the bone landmarks?
26:57
I don't even know a bone landmark was a thing,
but in general, there's a lot of memorization
26:59
in Anatomy & Physiology.
27:04
I like the part where it's conceptual, I don't
like the part where I'm memorizing bones.
27:05
<For my students, I try to tell them don't
memorize, or memorize as little as possible.
27:14
And the way to do that is to find what's common
between all the different things.
27:20
So for example, with the thing we just talked
about, if you know a few rules of how these
27:27
channels work and how cells are set up, you
know how nerves work, how muscles work and
27:33
how a bunch of our senses work.
27:36
So find those commonalities.
27:38
Now bones are kind of two parts, one is the
structural part and the other part of learning
27:39
them is learning the words and I think we're
27:46
going to talk about how to
learn all the words later.
27:47
>Yeah. We'll get there too.
27:49
<But as far as the bones, they're a really
physical thing.
27:51
And so I think the best way to learn a lot
of these details is really just to draw it
27:54
It's great if you have a model, a plastic
model in a lab, or, I mean, you have Stan
28:00
there behind you, you can get a skeleton,
28:06
a full skeleton online some
places, there's 3D apps.
28:10
But really, it's helpful to get your brain
to process it in a different way.
28:13
>This is well known that the more work you
are doing with your fingers,
28:19
the better you are learning.
28:26
So actually drawing, looking at a thing and
then closing it and then trying to draw it.
28:27
That is how-- that is how you learn things.
28:34
<Right. And I'm going to suggest something.
28:36
I like what you just said, that it's really
trying to draw up from memory.
28:39
Now, you take a femur or something like that,
28:44
there's a whole bunch of
little bumps and things on it.
28:46
And of course, it's three-dimensional, which
is hard to draw on paper.
28:49
So you do your best.
28:52
And I suggest starting with just the very
basic shape, don't even worry about all the
28:54
bumps the first time you draw it.
28:58
Look at the books, study it, get an idea for
the shape and then draw it.
29:00
And this is where, if you're a horrible artist
like me, my dad's an artist, I didn't get
29:04
those genes, and if you're
a horrible artist like me, it's actually good
29:08
because you don't worry about getting all
the little details and the shading, just get
29:12
Draw that and label whatever you can then
go back to your book or go back to whatever
29:17
kind of reference you're working on and see
where you could improve or see if you got
29:22
See if you could add one more detail or add
one more label.
29:28
And then close the resource, draw it again
only looking at your previous drawing.
29:32
So make it a little bit better, do it all
again, label what you can and then compare
29:37
it to the resource and just kind of go back
29:42
and forth and slowly build
up your knowledge that way.
29:44
If your teacher, like I do to my students,
29:48
I'll hand them a list of
300 terms to know in a lab.
29:52
And that's totally overwhelming.
29:56
Don't study the whole thing all at once.
29:58
One thing at a time, or
maybe two things at a time.
30:00
And so drawing is really good for that.
30:04
All right, we got a question that is from
a bunch of people, Gracie, Jamila, Ryan who
30:08
asks, it's all just generally about heart
function and ECGs and how ECGs work.
30:15
<Yeah, this is the other common stumbling block,
the nervous system and then this heart function.
30:22
>We have to sort of understand the whole cascade
of heart cells and what they're doing?
30:29
<Yeah. Well, we actually
already know some of that.
30:33
So there's really two parts to understanding
heart function.
30:35
One is electrical, and we mostly just talked
about that.
30:38
We can talk a little bit more about that.
30:42
And the other is really like physical and
this is when we talk about like-
30:43
>What happens in what order?
<Yeah, and pumping the blood that the pressure and
30:48
stuff that is involved in moving
the blood through the body.
30:52
So here's a rule and this
is again, mostly accurate.
30:56
Some physicists may not think that I'm phrasing
this properly,
31:01
but for the purposes of Anatomy &
Physiology, this is what you need to know.
31:04
Fluids move from high pressure to low pressure.
31:08
I mean, that's pretty simple, right?
31:12
And this is fluids including air and liquids
like blood.
31:15
So actually this tells us how we breathe,
how we move air in and out of our lungs.
31:18
It's high pressure and low pressure.
31:22
Okay, but back to the heart.
31:25
So what is the heart?
31:27
The heart is a muscle, right?
31:28
That's kind of where we started.
31:30
And so muscles contract, and when the heart
31:31
contracts, it produces
pressure inside of the heart.
31:34
And so this is how the blood is going to get
moved around but it's important that the heart
31:39
is not all contracting at all at once like
your gluteus maximus might contract when
31:47
you're running, right?
31:52
The heart actually contracts in kind of two parts.
31:53
So the top part of the heart, they're called
31:55
the atria so you have a left
atrium and a right atrium.
31:58
And then in the bottom half of the heart,
you have the ventricles, a left ventricle
32:01
and the right ventricle.
32:05
And the blood goes from atria on one side
to ventricles on the same side.
32:06
So what we want to have happen is the atria
to contract on top to send the of the blood
32:12
down to the ventricles.
32:16
And then once the ventricles are fully filled
up, then we want them to contract.
32:18
We don't want them contracting at the same
time as the atrium.
32:22
So there's this little delay in there.
32:25
That delay is actually part
of the electrical system.
32:29
So, again, we'll come back to that electrical
32:34
system so just kind of ignore
the delay for right now.
32:38
So the atria, they're going to squeeze and
create higher pressure, higher fluid pressure
32:40
or hydrostatic pressure than what we find
in the ventricles.
32:46
And therefore we have a pressure gradient
32:50
and the blood will flow from
atria down to ventricles.
32:51
When the atria are done squeezing, then the
big ventricles are going to squeeze at the
32:54
bottom and they can produce a lot of pressure.
32:58
And so they start squeezing.
33:00
As the pressure in the ventricles gets above
the pressure and the atria, then the blood
33:02
will want to flow to that
low pressure in the atrium,
33:08
and it will actually start to flow that direction.
33:12
But then it gets stuck on those valves that
we were talking about earlier, that kind of
33:13
leathery, tough connective tissue.
33:17
And we'll shut those valves, the backflow
33:19
will actually close those
valves and they slam shut.
33:23
And that kind of slamming shut and this pressure
wave that happens
33:26
is the first heartbeat sound that you hear, right?
33:30
So we talk about the lub-dub of
heartbeat sounds, the two sounds,
33:32
this is the lub, this is the first one.
33:37
Then the ventricle keeps contracting and keeps
building up pressure.
33:39
I mean, this all happens in a fraction of
the second so I'm kind of slowing this way down.
33:43
So as the pressure builds in the ventricle,
it eventually gets high enough that it's higher
33:48
than the pressure out in the big arteries,
like the aorta.
33:52
So the aorta at rest, when the heart is at
rest, is about 80 millimeters of mercury,
33:56
mercury abbreviated, Hg, there's your other
favorite one?
34:02
And that's your resting blood pressure, what
we call your diastolic blood pressure.
34:05
So if you have 120 over 80 for your blood
pressure, that's that bottom number.
34:12
So the ventricle's going to eventually get
higher pressure than the pressure in the aorta.
34:16
At that point, now we have a pressure gradient
again, and the blood is going to want to flow
34:22
from the high pressure in the ventricle to
the lower pressure in the aorta.
34:26
So then it'll actually open a valve called
34:30
the semilunar valve and will
push out into the aorta.
34:32
But at some point, the ventricle has squeezed
out almost all of its blood and so it can't
34:37
keep up with that pressure anymore and the
pressure in the ventricle will start to drop,
34:42
but there's still a lot of
pressure up in the aorta.
34:46
And so once we get that reverse pressure gradient,
again, the blood will try to flow from the
34:49
higher pressure in the ventricle or in the
aorta back into the ventricle.
34:54
And that little backflow will slam shut the
semilunar valves.
34:58
And that's the second sound that we hear.
35:02
So it's all about pressure differentials.
35:06
And this actually brings us to one of my favorite
35:10
Anatomy facts of all of
Anatomy & Physiology, right?
35:13
So think about the word circulatory system.
35:17
It means circle, right?
35:20
So the blood is traveling in a circle from
the heart back to the heart.
35:22
But if the heart is both the start and the
end and fluid flows from high pressure to
35:27
pressure, it means the heart is both the highest
35:34
pressure and the lowest pressure
just at different times.
35:38
>Yeah. And not just that, but a big differential,
35:43
because it has to push it
through all those tissues-
35:45
<Yeah
>like, tight spaces.
35:48
Yeah, so that ventricle
can develop 120 millimeters
35:51
of mercury of pressure up in the aorta and
35:55
it carries down your arm.
35:59
So when you get your blood pressure cuff put
on your arm, that's where it's measuring,
36:00
that's kind of basically getting that same
pressure from the heart.
36:04
And then the atrium and the ventricle, they
have to drop all the way back down to essentially
36:08
a pressure of zero in order to receive the
blood all the way back around the other side.
36:14
>Well, a physicist will argue about pressure
of zero.
36:19
<True. And this is all relative pressures kind of
too, so yeah, yeah.
36:23
We're all under, yeah.
36:29
<Yeah. And the thing that I also remember is that
that the work to fill up the lung with blood
36:31
is also just a huge amount of pressure necessary
for that just because there's so much...
36:41
<To fill it with blood or with air?
>With blood.
36:47
<Yeah, but it's actually less pressure.
36:50
>Not filling the lung with blood, filling all
of the alveoli and stuff with blood.
36:53
<Yeah, the capillaries with blood.
36:58
Yeah, it's actually far less pressure than
the other side.
37:01
So the left ventricle
develops about 120 millimeters
37:05
of mercury, by the population average 120
37:08
millimeters, the right ventricle is more like
30 or 40 millimeters.
37:11
>And that's what's pumping into the-
<that's what's pumping into the lungs.
37:16
Part of that is the lungs have a very thin
membrane between the blood capillaries and
37:20
the air because we want the air to be able
to pass through that membrane.
37:24
>You don't want to pop those?
<You don't want to pop those with
37:28
too high blood pressure.
37:29
It's also a shorter distance and there's some
other reasons why there's lower pressure,
37:31
but yeah, it's a very delicate system.
37:34
>Wildly delicate system and it works all of
the time and never stops working ever I promise.
37:37
<Never. So I think we still had
the electrical part of the heart.
37:43
>Oh God.
<I know. It's actually not that bad.
37:48
The signal is exactly what we talked about before.
37:53
It's these waves of voltage-gated channels,
sodium channels, opening and carrying the
37:55
signal around the heart.
38:00
It mostly starts in what we call the sin atrial
38:02
node, which is on the upper
right corner of the heart.
38:05
And it's a bunch of cells that they have actually
leakage channels, we mentioned before they
38:09
have some leakage sodium channels.
38:15
And so sodium is leaking in constantly and
causing that voltage to creep up.
38:17
And when the voltage hits the threshold voltage,
the massive signal goes all the way around
38:22
all the atrium and they contract and then
reset and then the sodium starts leaking in
38:28
and the voltage creeps up again.
38:34
And so the SA node has that automatic timer,
that's why we call it the internal pacemaker.
38:35
>Right, so there isn't a part of your brain,
some subconscious part of your brain that's
38:41
like, "Okay, make sure you
keep beating the heart."
38:45
The heart beats itself.
38:47
<The heart beats itself, the brain through
various mechanisms can turn that faster or
38:48
slower, but the heart beats itself.
38:53
>For when you need more oxygen--
<Right.
38:58
>because your big, big butt
muscles are pushing you along.
38:59
<Right. You get your fight or flight response and
your butt muscles have to push you along,
39:04
they need more oxygen, heart
rate's going to increase.
39:07
<Well, yeah, so we have this electrical signal
around the heart.
39:14
There's a little pause, it can't get through
those valves to the bottom, to the ventricle
39:17
so there's a little delay as it goes through
the atrioventricular node and then the electrical
39:22
signal gets dispersed from that and causes
the ventricles to contract.
39:26
>Okay, so it's the same signal that's causing the
ventricles to contract too?
39:30
<It is, it's like a fire hose through a pinhole.
39:34
It gets stuck at this thin little conduction
area and then that allows for that delay so
39:39
that the atria can contract and push their
blood down to the ventricles before the ventricles
39:46
contract and push the blood out.
39:50
>And it's a delicate system and if anything
goes wrong with it, that's why you have all
39:52
kinds of different heartbeat problems.
39:55
<All kinds of different heartbeat problems,
correct.
39:57
>Yeah. That's pretty cool.
And I'm glad that it works.
40:00
All right, Brandon, I want to ask you about some
40:06
tips and tricks for learning
about Anatomy & Physiology.
40:10
First of all, with regards
to learning these words.
40:14
>Yes. Lots of words.
40:17
Like I said before, memorize
as little as possible.
40:20
And one way to do that is to learn the root
words of things.
40:23
There's a lot of Latin and Greek, it doesn't
matter which one it is, but learn things like
40:27
epi, E-P-I, that means upon or on top of,
or you can phrase it in slightly different
40:32
ways, but really it's that idea of on or around.
40:39
So learn that word epi and then go find in
all of the systems, or all the systems you're
40:44
studying at that time, all
the words that start with epi.
40:50
So you have epidermis is on top of the dermis,
you have epicardium is the epithelial layer
40:53
upon the heart or around the heart.
41:01
You have epinephrine, which epi is on top
of or upon, and nephrine means kidneys.
41:05
So you'll see words like nephron and stuff
like that with kidneys.
41:10
Well, epinephrine means on top of the kidneys,
that's where the adrenal glands are that actually
41:14
make epinephrine or we also call it adrenaline
41:19
depending on which side of
the Atlantic Ocean you're on.
41:23
<So now none of us will ever
forget where the adrenal gland is.
41:25
>Right, they're epi of nephros.
41:29
<Yeah, which never had occurred to me that
epinephrine was at all related to even Anatomy.
41:32
I thought it was just a chemical name.
41:40
So there you go, now you'll never forget where
it is and now you know exactly what epi means
41:43
and you can figure out a lot of other words,
that's kind of the fun thing if you know the
41:49
words, instead of memorizing, you get to figure
out other things.
41:52
And then back to the bone question, right?
41:57
So how do you learn all of the landmarks?
41:59
Well, a lot of the landmarks have these repeating
names.
42:02
So you have fossas and foramen and
trochanters and grooves and a whole bunch of
42:05
names like that repeat over and over.
42:12
So pick one, like fossa, a
fossa is a shallow depression
42:15
in a bone usually where a muscle attaches.
42:21
And then go find all the fossas and figure
out where they are and what they look like.
42:23
And then as you put all these words together,
42:30
suddenly some words start
to make a lot more sense.
42:32
So on the scapula, on your shoulder blade,
there's a couple of large fossas one of them
42:34
is the infraspinus fossa of the scapula.
42:39
And that might seem like a kind of intimidating
word at first or set of words at first.
42:43
Well, infra means below, spinus is refers
to the spine that runs along the scapula,
42:47
not your vertebra spine, but the spine on
the scapula.
42:54
And then fossa is a shallow depression.
42:58
So the infraspinus fossa is the shallow depression
that sits below the spine of the scapula.
42:59
Once again, if you know those parts, that
word is a lot easier to remember and then
43:06
you can picture exactly where it is.
43:12
And even more helpful, the muscle that attaches
there is called infraspinatus.
43:13
<Which sounds like a disease.
43:19
And now we'll never forget about...yes, I will.
43:24
<Yeah. I mean, it's not /not/ work,
43:30
but this is a way
to make it less work
43:34
>And yeah, it makes it more fun I think, too.
It gives you tools instead of...
43:36
<Yeah. Instead of just memorizing.
43:43
Yeah, alright. You got any
other things, any other ways you
43:46
>Yeah. So a lot of my students tell me that they
make flashcards and flashcards are great but
43:52
I think you have to use them the correct way.
43:59
And we've learned a lot and there's the Crash
Course Study [Skills],
44:01
the whole course that covers some of this.
44:06
But one of the keys to using flashcards is
to randomize them and also use them to figure
44:08
out what you know and what you don't know.
44:17
And really we should all work
on our weaknesses at first.
44:19
It's easier to work on our strengths, we need
to work on our weaknesses.
44:22
So if you have flashcards and I've had students
come in with a stack of 300 index cards, beautiful
44:26
flashcards, artwork, all kinds of stuff on them.
44:32
And they say, "I'm studying them.
I'm not learning anything."
44:34
And I will show them what to do.
44:37
I'll take the whole stack, let's say this
is all the bones and bone landmarks and on
44:39
one side they have bones and on the other side
they have landmarks or something like that.
44:44
I take their whole stack of flashcards and
I throw them up in the air as high as I can
44:48
They scatter and they all flip over and then
we pick them up together.
44:54
Now, the order has changed and they're flipped
in different directions.
44:59
So that's part one.
45:05
Now that's already pretty good to just study
from those, but really you kind of have to
45:06
put yourself in a testing situation, you have
to use what's called recall practice.
45:11
And the way to do that, one way I suggest
doing that is to take maybe just the top 10
45:15
flashcards, don't flip them over, don't reorganize
them, exactly how you picked them up.
45:20
Take the top 10 and lay them out on your desk
and then get a piece of paper and put numbers
45:25
And if the first flashcard has a term on it
and the back has a definition, then you write
45:31
out the definition.
45:36
And if it has a definition, you write out
the term.
45:37
If it has, however you have your flashcard
set up, if it has a muscle name on it, you
45:39
write out the bone it connects to, or however
you cut it, right?
45:43
You give yourself a quiz using those top 10,
and then you go back...
45:47
Oh, and as you're answering, add a little
check mark or a star if you're really confident
45:52
in your answer, that you know it, then go
grade yourself by flipping over the flashcard.
45:57
So you haven't flipped them over yet, you
haven't cheated on your own test.
46:02
Now, flip them over, see if you got it right.
46:05
If you got it right and you were confident
in it, put it in a pile far away from you.
46:08
<It's gone. I don't need that.
>You're done. You don't need that.
46:13
<Don't waste time on that.
>Right.
46:15
If you got it right, but you weren't confident
put that in another pile, maybe you will get
46:17
back to that, but you knew it.
46:23
And unless you know it was a total guess,
you don't put that aside.
46:25
That's not where you really need to spend
your time.
46:30
Now you should be confident that you got it.
46:33
The ones that you got wrong, those stay close
to you and that's now your new pile.
46:35
And then that's what you study.
46:42
And then you do this again.
46:44
And then you study and then you do this again.
46:45
And so you're slowly moving cards into that
higher confidence or the correct piles and
46:47
your stack of stuff to study gets smaller
and smaller and smaller and you can feel like
46:52
you're learning stuff that way.
46:57
And in fact, you can get this in apps and
other things, the Crash Course App for Anatomy
47:00
& Physiology helps you track your confidence
and helps you figure out what you know and
47:05
you don't know in the same way.
47:09
<Mm-hmm (affirmative).
47:14
And then the last thing that you wrote down
here is to learn by teaching.
47:14
And I remember doing this to myself.
47:18
<Be like, how would I say this to me if I wanted
me to learn it?
47:23
And just restating or writing down in my own
47:29
words what I have learned because
that's the real synthesis.
47:32
>Yes. That's how I learn now is teaching myself.
47:36
That takes some practice, you really do have
to know what you don't know before I think
47:41
you can teach yourself.
47:46
And so that can be difficult.
47:47
I actually started, when I first took Comparative
Anatomy in graduate school out in Montana,
47:50
It was just someone else to talk to.
47:57
But she had big rippling muscles in short
bursts so when I was learning all the muscles,
48:00
She enjoyed just being pet, any attention
48:05
she could get, but I would
pet her and name the muscles.
48:07
Get a dog, but you got to make sure it's not
very shaggy, or one of those hairless cats.
48:10
>Right, right, right.
And so you can see the muscles.
48:19
I have students that say, "I don't have anyone
to teach.
48:27
My roommate is an English major."
48:30
Perfect, teach them.
48:32
They'll get really bored.
48:35
But they understand you know it.
48:36
<I'll tell you what, my wife hates this about me,
but she knows so many things now.
48:38
>I'm pretty sure my wife would say the same thing.
48:43
<"I have to tell you about this thing I learned."
48:45
It's definitely the best way because like
you said, it helps you process and reformulate
48:49
your own ideas so that someone else, even
if that someone else is you, can understand it.
48:54
We have a couple of chat questions.
49:01
I'm going to ask you a chat question.
49:03
And I'm curious about this from, from Katrina
who asks, "What happens when a muscle cramps?
49:05
>You know what, that's a good question.
49:14
That is not in my wheelhouse.
49:16
So I can't give you a definitive answer.
49:20
And I actually am a muscle physiologist,
49:24
but for birds and they never tell
me when their muscle is cramping.
49:26
>But what I will say is, so I'm not defining
what a muscle cramp is, but you can think
49:32
of all the steps of a muscle contraction and
what eventually could go wrong if the muscle
49:38
is cramping and it's actually contracting.
49:44
I do teach students about different kinds
of toxins and venoms as a way of learning
49:47
how muscles contract.
49:51
So you can have things that are kind of going
wrong on the nervous system side, either the
49:53
brain is constantly sending a signal or the
neuron is firing on its own too much or the
49:57
acetylcholine that's floating across and binding
to its channel, there's something wrong with
50:03
that channel and so the muscle cell thinks
it's constantly being told to contract.
50:08
You can also get problems in the muscle itself
where you can have say too much calcium in
50:14
the muscle and that's the final signal for
the actual contraction phase.
50:20
You can get electrolyte imbalances, right?
50:24
There's a lot of things that can interfere
with that nice clean system of signals that
50:27
we've talked about that could potentially
cause a muscle cramp.
50:34
But as far as a cramp during
exercise, I definitely
50:38
don't know enough to give a definitive answer.
50:41
I was told once and please check me on this
before you tell someone else, people listening,
50:44
that the reason that cramps hurt after a while
is because there's not enough blood to continue
50:50
the cramp, to continue the muscle flex, the
effort of it and the cramping can actually
50:57
constrict blood supply, the flexing of the
muscle itself can constrict blood supply because
51:04
the muscle is flexing.
51:08
>Yes. Muscle contraction in general changes blood
flow and can constrict it.
51:10
And muscles hurt a lot, like during a heart
attack, even cardiac muscle hurts a lot when
51:15
the oxygen delivery rate
is too slow for the demand.
51:21
<So if your chest hurts, go
to the doctor immediately.
51:28
>Yeah. Although importantly, this is surprisingly
not well known, for women having heart attacks
51:33
that pain is not usually-
<It can be different, yeah.
51:40
>Yeah, it's often actually more like fatigue.
51:44
<Yeah. And it can be referred
more often in the neck
51:48
>Yeah, the pain can show up in different places.
51:51
<Mm-hmm (affirmative). Stupid bodies.
51:53
William had a question, do you have any tricks
for remembering the veins and the arteries?
51:57
>You know, I actually do.
52:03
It worked for me, I think it works for a lot
of my students, and that's to draw a map.
52:05
And like I said before with
the bones, start simple.
52:10
And the best maps, they're not really accurate.
52:13
They actually are easier to follow.
52:16
So think of a subway map or a transit map
where you can see the order of things and
52:19
you can see the connections, but it's not
like it's geographically 100% accurate.
52:24
So if you draw your map and just start by
thinking, "I'm giving someone directions to
52:31
the spleen or to the stomach, how do I get
from the heart down there?"
52:38
And you just learn that part first.
52:42
And then you say, "Well, what if I also wanted
to go down to the leg?"
52:46
Then you go to the spleen, you draw your map
to the spleen so just to refresh your brain,
52:51
and then you continue, you go past that turn
and you go to the leg and you label it.
52:56
So again, start with just a few arteries and
veins and label them and then build up on that.
53:02
Every time you redraw it, just add a few more,
adding a few more turns.
53:09
It's like learning your way
around a new city, right?
53:13
You learn just one simple path from home to work,
53:16
and then you start learning
the scenic routes around that.
53:19
Once you get that pathway down, then say you're
dissecting, you're looking at a much more
53:24
realistic model, it's much easier to find
the actual arteries and veins because you
53:29
can always go back to the aorta and start
from there, start from where you know, and
53:33
then follow the arteries and veins out in
the dissection.
53:40
And if you know your map well enough, then
you will be able to follow the actual things.
53:43
<Right. And also you know where you lose track, if
you're following a map you know and then you
53:48
reinforce the most common boulevards, the
bigger roads.
53:55
And so every time you're going down, you're
reinforcing that, the most important and the
54:00
most common bits before you get to the branches
that are going to be harder to remember because
54:06
there are so many of them.
54:13
And that's kind of part of spaced repetition,
which is the learning strategy of repeating,
54:15
but making sure to space it out over days
or weeks or even longer-
54:21
<It's so hard to do because that is not how I am
54:25
tested or was tested.
>No, it's not, no.
54:29
<It was like here, get the information, then
take the test and then forget it forever.
54:32
>Until maybe the final exam.
54:36
<Yeah, exactly. Yeah.
54:38
>But if you're in an anatomy class sure, sure
you probably need to get a certain grade to
54:39
continue on in whatever program, but it's
probably not the last time you're going to
54:45
see this stuff and that's big spaced repetition.
54:49
You see it maybe first year in college or
community college and then you might not see
54:52
it again until four years later.
54:57
But if you work hard in that first year, it'll
be there.
54:59
<It's amazing how much stuff is still there.
55:03
I recently started learning Spanish again
and I hadn't looked at it since my freshman
55:05
year of college and I was like, "Wow, there's
a fair amount of Spanish still in this brain."
55:11
So yeah, they're amazing organs.
Okay. Well.
55:16
I feel as if I learned some wonderful things
about Anatomy & Physiology.
55:20
So thank you, everybody, for asking thoughtful
questions, and thanks again to Flipgrid for
55:24
sponsoring the livestream, making it all happen,
and you can check them out, there's a link
55:28
to them in description below.
55:33
Brandon, thank you very much for all of your
expertise and yeah, I just really appreciate
55:34
>Yeah. And Hank, thank you
for Crash Course, I know
55:41
it's helped a lot of my students
in lots of different classes.
55:44
I think it's been a great resource.
55:47
<Well, thanks so much.
55:49
Thank you for contributing to it and
making Anatomy & Physiology possible.
55:50
Thank you all for joining us.
55:55
I have been Hank Green,
that's been Brandon Jackson.
55:57
It's been a good old time!
56:01