Muscle 3- Hierarchical organization

Muscle 3- Hierarchical organization

– All right, a skeletal
muscle organ is made up of many
bundles of tissue. So let’s look
at what makes up this organ. First of all, you know
that our skeletal muscle usually attaches to a bone. And you also hopefully
are comfortable with the idea that
the skeletal muscle attaches to the bone at a tendon.
Does that work for you? And a tendon, we’re going
to talk in a second about what makes up
the tendon itself. I’m going to give you
a little hint by doing this kind of a cross-section
of a skeletal muscle, where this right here
is the muscle organ or the muscle tissue. Now, can you visualize how I
could actually carry this out and make an entire muscle, and then have another bone
that it attaches to? And we would have striations in this thing that would
indicate fiber direction. And then those fibers
would shorten and that would shorten
the muscle and bring
the two bones together. Do you have a vision
for where we are? Okay. Look, we’re going
to do a cross-section in my crazy visual. This is the organ,
the muscle organ. And each level of organization is covered
with a connective tissue casing and the muscle organ is covered in a connective tissue casing
called epimysium, epimysium. Epimysium surrounds the entire
muscle organ. When we go in
and look at our bodies, we can actually grab
an entire muscle organ and the connective
tissue that covers it, that’s the epimysium.
This is not on accident. It’s on purpose that you notice that the epimysium is the same
color as my tendon, and that’s because
the epimysium is a structure that eventually becomes tendon. It’s what actually connects
to the bone the organ itself. Now the muscle organ is made of these structures
called fascicles. So if you were to do
a cross-section of a muscle organ you would
see these circular fascicles. And the fascicles, let’s just name them fascicles,
fascicles. The fascicles are surrounded
by their own connective tissue what, covering. So each fascicle is surrounded
by a connective tissue. It’s not epi on the outside
and it’s not endo on the inside, so that gives you a hint
to what we’re looking at here. This is actually called peri,
perimysium. Perimysium surrounds
each individual fascicle. If you go– we talked about in
the last section how you could, like, string beef or steak
or meat that you eat, you can pull pieces of it
and like string it all up, you can make
a pulled pork sandwich. All of those pulled pieces
that you string out, those are all fascicles
surrounded in perimysium. The perimysium actually
keeps the fascicle together. The epimysium keeps the whole
organ together. Now, if we were to take
the fascicle out like, dude, what is this fascicle
that you speak of, Riggs? Look, oh, a fascicle is a bundle
of something. And are you ready to know
what the bundle of it is? Okay, watch. Oh, look at my incredible–
dang it. I wish I would have used
a different color. I did not use a different color. Some opportunities are
just lost. This little thing
that I pulled out, that there are a whole bunch of
them that make up the fascicle, this is called a myofiber. Oh, my-o-fiber,
the plot thickens. A myofiber is a muscle cell. Man, I wish I would have made
that a different color. It makes me mad.
Myofibers, okay, seriously, it’s a cell.
It’s like a piece of spaghetti. That’s how long it is. And it’s filled with all sorts of other stuff
but this is my muscle cell. Now, cells have nuclei.
This is my nucleus. And I’m putting, I’m
showing you the nuclei, that one kind of bulged on out. But they have many nuclei and I already told you that
in the previous section. So we’ve got lots of nuclei in
a single muscle fiber and you know we got to be
covered in something, doggies. What would you be covered
in if you could cover? I mean but, of course, it’s another connective
tissue covering. Doggies, that’s your endomysium. How awesome is that?
So you’ve got the muscle. The muscle is made up of bundle
of fascicles and the fascicle is actually a bundle of myofibers
or the cells themselves. Now we’re not even
close to being done. What?
You would think we’d be done. Inside the muscle cell, inside the myofiber
there is actually these, like, whoa, holy– I don’t know what to say. Like, it’s just filled with
these spaghetti noodle long protein fibers,
bundles. So watch this. I’m going to have to make
it like what, orange? Sure.
What? Inside each one of my myofibers are these little protein
bundles called myofibrils. True story. What is a myofibril?
Are you ready for this? We don’t have any more
connective tissue going on. Myofibrils are bundles
of myofilaments. Now, we have two flavors
of myofilaments. We have thick and
thin myofilaments. You can call them thick and
thin filaments, that’s fine. Calling them myofilaments lets you know where
we’re talking about. So let’s do it one more
time just for the fun of it. Muscle organ is
made up of bundles of muscle cells called
fascicles. Muscle cells are
made up of bundles of myofilaments called
myofibrils. The functional unit of a
skeletal muscle organ is inside the myofiber and it’s a
thing that we’re going to see here in a second that results
from the organization of the thick and thin filaments
inside my myofibrils. Now, if you’re feeling like
holy crap, take a second. Take a deep breath.
Go study. Make sure this organization of the muscle organ is
comfortable to you, because we’re about to
go into the myofibril and the myofilaments
in a lot more detail. Before we do that,
take a look at– I highly recommend going around and looking at many
different illustrations. But if you can see
this illustration here, here’s my organ.
My organ is made up of bundles. Each bundle is made up of cells. Each cell, here’s a cell,
here’s a nucleus, each cell is made up
of myofibers, fibrils. These are my myofibrils
and each myofibril is made up of myofilaments.
What? True story.
Right. Let’s look closer at the
myofilaments and how they do what they’re
supposed to do. And make sure you’re
comfortable with the organization before you
do that. Okay, bye-bye.

10 Replies to “Muscle 3- Hierarchical organization”

  1. These videos have been priceless and I'm super super grateful. If there's anything I can do to show my support on youtube let me know!

  2. Very informative…!!! Just started ACE certification…looking forward to a next videos…Thank you!!!

  3. Wendy, this topic is a very hard one, cz it has many steps involved. I gave up on my book, closed it and hoped Wendy could save me and thats how I landed here.
    My concepts of this chapter are clear and A1 now cz of you.Lots of love from UK ❤

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