Flo Hyman had always been a tall girl I
mean really tall
I heard twelfth birthday she was already
six feet in by 17 she topped out in just
over six five initially self-conscious
about her stature she learned to use it
to her advantage when she started
playing volleyball she attended the
University of Houston as the school's
first female scholarship athlete and at
the age of twenty-one she was competing
in the World Championships nine years
later she made it to the 1984 Olympics
and helped her team win the silver medal
after the Olympics Hyman moved to Japan
where she gained fame playing
professional volleyball but all of that
ended in 1986 when out of nowhere she
collapsed and died during a game she was
31 years old
diamonds initial cause of death was
thought to be a heart attack but an
autopsy revealed that she died from a
tear in her aorta caused by an
undiagnosed condition known as Marfan
syndrome Marfan syndrome is a genetic
disorder of the connective tissue people
suffering from it have a defect in their
connective tissue that substantially
weakens it over time and you got
connective tissue pretty much everywhere
in your body so it could cause some big
problems I relate those with Marfan's
tend to be especially tall and thin like
Flo Hyman with loose flexible joints and
noticeably longer limbs and fingers
those long fingers and bendy joints have
actually helped some athletes and
musicians do things that the rest of us
can't famous blues guitarist Robert
Johnson piano virtuoso Sergei
Rachmaninoff and Italian violinist
niccolò paganini are all believed to
have had Marfan syndrome but these
abilities come at a great cost as people
with Maher fans get older their
weakening tissue can cause serious
problems in the joints eyes lungs and
heart the fact that a single genetic
mutation can affect your bones cartilage
tendons blood vessel walls and more
shows that all of these structures are
closely related no matter how different
they may seem we've covered the basic
properties of nervous muscle and
epithelial tissue but we haven't gotten
to the most abundant and diverse of the
four tissue types our connective tissue
this is the stuff that keeps you looking
young makes up your skeleton and
delivers oxygen and nutrients throughout
your body it's what holds you together
in more ways than one and if something
goes wrong with it
you're in for some havoc and that means
we're gonna be talking about jello today
we'll get to that in a minute
the spring is here that's connective
tissue so is the structure in here and
the stuff inside here and the tendons
popping out here a connective tissue is
pretty much everywhere in your body
although how much of it shows up where
varies from organ to organ for instance
your skin is mostly connective tissue
while your brain has very little since
it's almost all nervous tissue you've
got four major classes of connective
tissue proper or the kind of defining
your ligaments and supporting your skin
along with cartilage bone and blood wha
sounds a little weird but your bones and
your blood are just types of connective
tissue so despite the name your
connective tissues do way more than just
connect your muscles to your bones your
fat which is a type of proper connective
tissue provides insulation and fuel
storage whether you like it or not but
it also serves structural purposes like
holding your kidneys in place and
keeping your eyeballs from popping out
of your skull your bones tendons and
cartilage bind support and protect your
organs and give you a skeleton so that
you can move with a purpose instead of
bobbing around like an amoeba and your
blood transports your hormones nutrients
and other material all over your body
there's no other substance in you that
can boast this kind of diversity but if
they're so different how do we know that
anything is a connective tissue well all
connective tissues have three factors in
common that set them apart from other
tissue types first they share a common
origin they all developed from
mesenchyme a loose and fluid type of
embryonic tissue
unlike cells that go on to form say your
epithelium which are fixed and neatly
arranged in sheets mesenchymal cells can
be situated any which way and can move
from place to place connective tissues
also have different degrees of
vascularity or blood flow most cartilage
is a vascular for example meaning it has
no blood vessels while other types of
connective tissue like the dense
irregular tissue in your skin is
brimming with blood vessels finally and
as strange as it may sound all
connective tissues are mostly composed
of nonliving material called the
extracellular matrix while other tissue
types are mainly made of living cells
packed together the inert matrix between
connective tissue cells is actually more
important than what's inside the cells
basically your connective tissue when
you see it up close looks and acts a lot
like this yeah the most abundant and
diverse tissue in your body that makes
all of your movements and functions
possible turns out that's not that
different from the dessert that Aunt
Frances brings to every holiday party
the jello that gives this confection its
structure is like that extracellular
matrix in your connective tissue the
actual cells are just intermittent
little goodies floating around inside
the matrix like the little marshmallows
and although it may not look like it in
this particular edible model the
extracellular matrix is mostly made of
two components the main part is the
ground substance a watery rubbery
unstructured material that fills in the
spaces between cells and like the
gelatin in this dessert protects the
delicate delicious cells from their
surroundings the ground substance is
flexible because it's mostly made of big
old starch and protein molecules mixed
with water the anchors of this framework
are proteins called proteoglycans and
from each one sprouts lots and lots of
long starchy strands called
glycosaminoglycans or GA GS radiating
out from those proteins like brush
bristles these molecules then clump
together to form big tangles that trap
water and if you've ever made glue out
of flour you know that starch protein
and water can make a strong and gooey
glue but running throughout the ground
substance is another important component
fibers which provide support and
structure to the otherwise shapeless
ground substance and here too are lots
of different types collagen is by far
the strongest and most abundant type of
fiber tough and flexible it's
essentially a strand of protein and
stress tests show that it's actually
stronger than a steel fiber of the same
size it's part of what makes your skin
look young and plump which is why
sometimes we inject it into our faces in
addition you've also got elastic fibers
which are longer and thinner and form a
branching framework within the matrix
they're made out of the protein elastin
which allows them to stretch and coil
like rubber bands they're found in
places like your skin lungs and blood
vessel walls
finally there are reticular fibers short
finer collagen fibers with an extra
coating of glycoprotein these fibers
form delicate sponge-like networks that
cradle and support your organs like
fuzzy Nets so there's ground substance
and fibers in all connective tissue but
let's not forget about the cells
themselves where the tissue is diverse
as this naturally there are all kinds of
connective tissue cells each with its
unique and
we'll task from building bone to storing
energy to keeping you from bleeding to
death every time you get a paper cut but
each of these signature cell types
manifest itself in two different phases
immature and mature you can recognize
the immature cells by the suffix they
all share in their names blast blast
sounds kind of destructive but literally
it means forming these are the stem
cells that are still in the process of
dividing to replicate themselves but
each kind of blast cell has a
specialized function namely to secrete
the ground substances and fiber that
form its unique matrix so chondroblasts
for example are the blast cells of
cartilage when they build their matrix
around them they're making the spongy
tissue that forms your nose and ears and
cushions your joints likewise
osteoblasts are the blast cells of bone
tissue and the matrix they lay down is
the nexus of calcium carbonate that
forms your bone once they're done
forming their matrix these blast cells
transition into a less active mature
phase at that point they trade in blast
for the suffix site so an osteoblasts in
your bone becomes an osteocyte ditto for
chondroblasts becoming chondrocytes
these site cells maintain the health of
the matrix built by the blasts but they
can sometimes revert back to their blast
state if they need to repair or generate
a new matrix so the matrices that these
cells create are pretty much what build
you they assemble your bone in your
cartilage in your tendons and everything
that holds the rest together not bad for
a bunch of marshmallows floating in
jell-o but there is another class of
connective tissue cells that are
responsible for an equally important
role and that is protecting you from
pretty much everything these are cells
that carry out many of your body's
immune functions I'm talking about
macrophages the big hungry guard cells
that patrol your connective tissues and
eat bacteria foreign materials and even
your own dead cells and your white blood
cells or leukocytes that scour your
circulatory system fighting off
infection their connective tissue cells
- you can see how pervasive and
important connective tissue is in your
body so a condition that affects this
tissue like Marfan syndrome can really
wreak havoc one of the best ways of
understanding your body's structures
after all is studying what happens when
something goes wrong with them in the
case of your connective tissue Marfan
syndrome affects those fibers we talked
about that lends structure and support
to the extracellular matrix most often
it targets the alas
dick fibers causing weakness in the
matrix that's the root of many of the
conditions most serious symptoms about
90% of the people with the disease
experience problems with the heart and
the aorta the biggest and most important
artery in the body when the elastic
fibers around the aorta weaken they
can't provide the artery with enough
support so over time the aorta begins to
enlarge so much so that it can rupture
this is probably what happened to Flo
Hyman she was physically exerting
herself and her artery without the
support of its connective tissue
couldn't take the stress and it tore
there's so much going on with your
connective tissue so many variations
within their weird diversity that we're
gonna spend one last lesson on them next
week exploring the subtypes that come
together to make you possible but you
did learn a lot today you'll learn that
there are four types of connective
tissue proper cartilage bone and blood
and that they all developed from
mesenchyme have different degrees of
blood flow and are mostly made of
extracellular matrix full of ground
substance and fibers we touched on
different blasts in sight and immune
cell types and discussed how Marfan
syndrome can affect connective tissue
thanks for watching especially to our
subbable subscribers who make crash
course possible for themselves and also
for the rest of the world to find out
how you can become a supporter just go
to subbable.com this episode was written
by Kathleen Yale edited by Blake de
pastino and our consultant is dr.
Brandon Jackson our director and editor
is Nicholas Jenkins the script
supervisor and sound designer is Michael
Aranda and the graphics team is thought
cafe
you