Tissues, Part 3 - Connective Tissues: Crash Course Anatomy & Physiology #4

Summary

The video script tells the story of Flo Hyman, a renowned volleyball player whose life was tragically cut short by Marfan Syndrome, a genetic disorder affecting connective tissue. It delves into the diverse roles of connective tissue in the body, from providing support and structure to facilitating immune functions. The script uses an analogy of jello to explain the extracellular matrix, highlighting the importance of ground substance and fibers in maintaining bodily functions. It also discusses the impact of Marfan Syndrome on the body's structure and the potential complications it can cause.

Takeaways

• 🏐 Flo Hyman was a renowned volleyball player whose height was a result of Marfan Syndrome, a genetic disorder affecting the body's connective tissue.
• 📏 Marfan Syndrome causes the connective tissue to weaken over time, leading to physical traits such as tall stature, long limbs, and flexible joints.
• 🎼 Notable musicians like Robert Johnson, Sergei Rachmaninov, and Niccolo Paganini are believed to have had Marfan Syndrome, which may have contributed to their unique talents.
• 💔 The condition can lead to severe health issues, including problems with the joints, eyes, lungs, and heart, as seen in the tragic death of Flo Hyman due to an aortic tear.
• 🦴 Connective tissue is the most abundant and diverse tissue in the body, playing a crucial role in maintaining structure, delivering oxygen and nutrients, and providing support.
• 🧬 Connective tissues originate from mesenchyme, an embryonic tissue, and vary in vascularity, with some like cartilage being avascular and others rich in blood vessels.
• 🕊️ The extracellular matrix is the main component of connective tissue, composed of ground substance and fibers, providing a supportive framework for cells.
• 🔬 The ground substance is a flexible, watery material made of starch and protein molecules, while fibers like collagen provide strength and elasticity.
• 🌱 Immature connective tissue cells, known as -blast cells, are responsible for producing the extracellular matrix, transitioning into mature -cyte cells after matrix formation.
• 🛡️ Connective tissue also includes immune cells like macrophages and leukocytes, which protect the body by consuming bacteria, foreign materials, and dead cells.
• 🧬 Marfan Syndrome specifically affects the fibers in the extracellular matrix, often targeting elastic fibers and causing weakness that can lead to life-threatening conditions like aortic rupture.

Q & A

What was Flo Hyman's height at the age of 12 and 17?

By her 12th birthday, Flo Hyman was already six feet tall, and by the age of 17, she had grown to just over 6'5''.

How did Flo Hyman's height initially affect her?

Initially, Flo Hyman was self-conscious about her height, but she later learned to use it to her advantage in playing volleyball.

What was significant about Flo Hyman's time at the University of Houston?

Flo Hyman attended the University of Houston as the school's first female scholarship athlete.

What achievement did Flo Hyman accomplish at the 1984 Olympics?

At the 1984 Olympics, Flo Hyman helped her team win the silver medal in volleyball.

What was the initial cause of death attributed to Flo Hyman?

Initially, Flo Hyman's death was thought to be due to a heart attack.

What condition did Flo Hyman have that was revealed after her autopsy?

An autopsy revealed that Flo Hyman had Marfan Syndrome, which caused a tear in her aorta and led to her death.

What is Marfan Syndrome and how does it affect the body?

Marfan Syndrome is a genetic disorder of the connective tissue that causes a defect in the tissue, weakening it over time and affecting various parts of the body, including the joints, eyes, lungs, and heart.

What are the physical characteristics often associated with Marfan Syndrome?

People with Marfan Syndrome tend to be especially tall and thin, with loose, flexible joints and noticeably longer limbs and fingers.

What are the four main classes of connective tissue?

The four main classes of connective tissue are proper, cartilage, bone, and blood.

What is the extracellular matrix and why is it important in connective tissue?

The extracellular matrix is a nonliving material that makes up the majority of connective tissue. It provides structure and support, and is composed of the ground substance and fibers.

How do connective tissue cells develop and what are their functions?

Connective tissue cells develop from mesenchyme and differentiate into various types, such as chondroblasts and osteoblasts, which are responsible for forming the matrix of cartilage and bone, respectively. Once the matrix is formed, these cells mature into less active forms, like chondrocytes and osteocytes, which maintain the health of the matrix.

What is the role of immune cells in connective tissue?

Immune cells, such as macrophages and leukocytes, play a crucial role in connective tissue by patrolling the tissues, consuming bacteria, foreign materials, and even dead cells, thus protecting the body from infections and other threats.

How does Marfan Syndrome affect the connective tissue and lead to serious symptoms?

Marfan Syndrome affects the elastic fibers in the connective tissue, causing weakness in the extracellular matrix. This can lead to serious symptoms such as aortic enlargement and potential rupture, which is believed to be the cause of death for Flo Hyman.

Outlines

00:00

🏐 The Life and Legacy of Flo Hyman

This paragraph tells the story of Flo Hyman, a remarkable volleyball player who stood out due to her exceptional height, reaching over 6 feet by the age of 12 and 6'5'' by 17. Initially self-conscious, she harnessed her height to excel in volleyball, becoming the first female scholarship athlete at the University of Houston and later competing in World Championships and the 1984 Olympics, where she won a silver medal. After her Olympic success, she turned professional in Japan. Tragically, her life was cut short at 31 during a game due to Marfan Syndrome, a genetic disorder affecting the body's connective tissue, which led to a fatal tear in her aorta. The paragraph also touches on the unique physical traits associated with Marfan Syndrome and its impact on various notable figures in history.

05:01

🧬 Understanding Connective Tissue and Marfan Syndrome

This paragraph delves into the world of connective tissue, the body's most abundant and diverse tissue type, responsible for maintaining structure, delivering oxygen and nutrients, and providing support. It explains the four main classes of connective tissue: proper, cartilage, bone, and blood, all originating from mesenchyme. The paragraph highlights the importance of the extracellular matrix, composed of ground substance and fibers, which provides the structural framework for the body. It further discusses the various types of fibers, including collagen, elastic fibers, and reticular fibers, and their specific roles. The paragraph also describes the different types of connective tissue cells, including their immature (-blast) and mature (-cyte) forms, and their functions in tissue repair and maintenance. The impact of Marfan Syndrome on connective tissue is emphasized, particularly its effects on elastic fibers and the serious complications it can cause, such as aortic dissection, as exemplified by Flo Hyman's case.

10:02

🎬 Behind the Scenes of Crash Course Production

The final paragraph shifts focus from the scientific content to the production aspects of the video. It credits the writing of Kathleen Yale, editing by Blake de Pastino, and consultation by Dr. Brandon Jackson. The director and editor is Nicholas Jenkins, with Michael Aranda serving as script supervisor and sound designer. The graphics team from Thought Café is also acknowledged for their contribution to the episode. This paragraph provides a brief overview of the collaborative effort behind creating the educational content of Crash Course.

Keywords

💡Flo Hyman

Flo Hyman was a renowned volleyball player known for her exceptional height, which was a result of her having Marfan Syndrome. Her story is central to the video as it illustrates the impact of Marfan Syndrome on an individual's life and career. The script mentions her progression from being self-conscious about her height to becoming a successful athlete, and ultimately, the tragic consequence of her condition during a game.

💡Marfan Syndrome

Marfan Syndrome is a genetic disorder affecting the body's connective tissue, leading to various physical manifestations such as tall stature, long limbs, and flexible joints. The video uses Marfan Syndrome as a focal point to discuss the importance of connective tissue and its role in the body. The condition is highlighted through the narrative of Flo Hyman's life and the autopsy findings that revealed the cause of her death.

💡Connective Tissue

Connective tissue is the most abundant and diverse tissue type in the human body, responsible for providing support, protection, and structure. In the video, connective tissue is described as being crucial for maintaining the body's integrity and facilitating movement. The script explains how connective tissue is composed of an extracellular matrix and cells, and how abnormalities in this tissue, as seen in Marfan Syndrome, can lead to serious health issues.

💡Extracellular Matrix

The extracellular matrix is a nonliving material found in connective tissues that provides structural and functional support. The video likens the extracellular matrix to the gelatin in a dessert, highlighting its importance in maintaining the shape and function of tissues. The script explains that the matrix is composed of ground substance and fibers, which are essential for the tissue's properties.

💡Ground Substance

Ground substance is a component of the extracellular matrix that is described as watery and rubbery, filling the spaces between cells and providing flexibility. The video script uses the analogy of gelatin in Jello to explain the role of ground substance, emphasizing its protective and structural functions within connective tissues.

💡Fibers

Fibers in the context of connective tissue refer to protein structures that provide support and strength. The video script mentions different types of fibers, such as collagen, elastic fibers, and reticular fibers, each serving specific functions within the body. For example, collagen is highlighted for its strength and role in maintaining youthful skin, while elastic fibers allow for stretching and recoiling in tissues like skin and blood vessels.

💡Proteoglycans

Proteoglycans are proteins that play a crucial role in the extracellular matrix by providing a framework for the tissue. The script describes proteoglycans as having long, starchy strands called glycosaminoglycans that radiate out like brush bristles, contributing to the matrix's structural integrity and ability to trap water.

💡Mesenchyme

Mesenchyme is a type of loose and fluid embryonic tissue from which all connective tissues develop. The video script explains that mesenchymal cells are not fixed in place and can move, unlike epithelial cells, which are arranged in sheets. This characteristic is fundamental to the diverse functions of connective tissues throughout the body.

💡Vascularity

Vascularity refers to the presence of blood vessels within a tissue. The video script contrasts avascular tissues, like most cartilage, with those rich in blood vessels, such as dense irregular connective tissue in the skin. Understanding vascularity is key to appreciating the diverse functions and characteristics of different types of connective tissues.

💡Blast Cells

Blast cells, identified by the suffix '-blast', are immature connective tissue cells that are responsible for the formation of the extracellular matrix. The video script uses examples like chondroblasts and osteoblasts to illustrate how these cells secrete the substances necessary for building cartilage and bone, respectively. Once the matrix is formed, these cells mature and transition into their respective '-cyte' forms.

💡Cyte Cells

Cyte cells, identified by the suffix '-cyte', are mature connective tissue cells that maintain the health of the extracellular matrix. The video script explains that these cells, such as osteocytes and chondrocytes, are derived from blast cells and play a crucial role in the upkeep and potential repair of the tissue matrix they are part of.

💡Macrophages

Macrophages are a type of connective tissue cell that serve as immune cells, patrolling tissues and engulfing bacteria, foreign materials, and dead cells. The video script highlights the role of macrophages in the body's defense mechanisms, demonstrating the multifunctional nature of connective tissue and its cells.

Highlights

Flo Hyman was exceptionally tall, reaching 6'5" by age 17, and used her height to excel in volleyball.

Hyman was the first female scholarship athlete at the University of Houston and competed in World Championships at 21.

She won a silver medal at the 1984 Olympics and later played professional volleyball in Japan.

Tragically, Flo Hyman died at 31 from a tear in her aorta caused by Marfan Syndrome, an undiagnosed genetic disorder.

Marfan Syndrome affects the body's connective tissue, leading to serious health complications.

Individuals with Marfan Syndrome often exhibit physical traits such as tall stature, long limbs, and flexible joints.

Marfan Syndrome has been linked to exceptional abilities in some musicians and athletes, but it also brings significant health risks.

Connective tissue is the most abundant and diverse tissue type in the human body, playing a crucial role in structure and function.

Connective tissues have unique properties, including a common origin from mesenchyme and varying degrees of vascularity.

The extracellular matrix is a key component of connective tissue, providing structure and support.

Ground substance and fibers are the main components of the extracellular matrix, with collagen being the strongest and most abundant fiber.

Connective tissue cells play a variety of roles, from building bone to immune functions.

Macrophages and leukocytes are connective tissue cells that perform important immune functions in the body.

Marfan Syndrome can cause severe symptoms, particularly affecting the heart and aorta due to weakened elastic fibers.

The study of connective tissue disorders like Marfan Syndrome provides insights into the body's complex structures and functions.

Crash Course episode on connective tissue was written by Kathleen Yale, edited by Blake de Pastino, and consulted by Dr. Brandon Jackson.

Transcripts

Flo Hyman had always been a tall girl.

I mean... really tall.

By her 12th birthday, she was already six feet, and by 17 she’d topped out at just over 6’5’’.

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 21, she was competing in 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.

Hyman’s 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’ve got connective tissue pretty much everywhere in your body, so it can cause big problems.

Outwardly, those with Marfan’s tend to 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 Rachmaninov,

and Italian violinist Niccolo Paganini are all believed to have had Marfan Syndrome.

But these abilities come at a great cost -- as people with Marfan’s 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 those 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 talkin’ about Jello today.

Uh…we’ll get to that in a minute.

The springiness here? That’s connective tissue. So is the structure in here, and the

stuff inside here, and the tendons popping out here

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 main classes of connective tissue -- proper, or the kind you’d find

in your ligaments and supporting your skin, along with cartilage, bone, and blood.

Whaaaa?

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 blobbing 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 develop from mesenchyme, a loose and fluid

type of embryonic tissue. Unlike the 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 avascular, 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 it’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 ol’ 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 GAGs, 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 recoil 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.

With a tissue as diverse as this, naturally there are all kinds of connective tissue cells,

each with its unique and vital 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 manifests 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 kinda 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 -cyte. So an osteoblast in your bone becomes an osteocyte

-- ditto for chondroblasts becoming chondrocytes.

These cyte 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 and your cartilage and your tendons and everything that holds the rest together.

Not bad for a bunch of marshmallows floating in jello.

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, they’re connective tissue cells, too.

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 lend structure and support to

the extracellular matrix.

Most often, it targets the elastic fibers, causing weakness in the matrix that’s the

root of many of the condition’s most serious symptoms.

About 90 percent 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 going to 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 learned that there are four types of connective tissue

-- proper, cartilage, bone, and blood -- and that they all develop 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, and cyte, 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 Café.