Blood, Part 2 - There Will Be Blood: Crash Course Anatomy & Physiology #30
Summary
TLDREl script explora la temática del dopaje sanguíneo, destacando la importancia de los glóbulos rojos y su función crucial en el transporte de oxígeno. Se describe la forma y función de los eritrocitos, su ciclo de vida y la regulación por la hormona EPO. Además, se aborda el riesgo y la prohibición del dopaje, que implica aumentar artificialmente la producción de glóbulos rojos para mejorar el rendimiento deportivo, pero que puede llevar a complicaciones serias como coágulos sanguíneos y fallo cardíaco. El video proporciona una visión detallada de la biología sanguínea y los peligros del dopaje, con una referencia irónica al caso de Lance Armstrong.
Takeaways
- 🚴♂️ Doping es un tema relevante en el deporte, como se vio en el caso de Lance Armstrong, quien manipuló su sangre para ganar la Vuelta a Francia siete veces.
- 🩸 La sangre tiene un poder tremendo, en gran parte debido a las glóbulos rojos (eritrocitos), que son responsables de transportar oxígeno a todo el cuerpo.
- 🔴 Los eritrocitos son células peculiares que se dejan de su núcleo y otros organelos para maximizar su eficiencia en el transporte de oxígeno.
- 🧬 El hemoglobina, una molécula presente en un 97% de los glóbulos rojos, es esencial para la captura y liberación de oxígeno, similar a una esponja de oxígeno.
- 🔵 No todos los animales tienen sangre roja; por ejemplo, los moluscos tienen sangre azul debido a la presencia de hemocyanina, una proteína que contiene cobre.
- 🚫 La dopaje sanguíneo, que implica aumentar el número de glóbulos rojos, es peligroso ya que puede hacer que la sangre se vuelva demasiado viscosa y dificultar la circulación.
- 🚑 El dopaje sanguíneo es perjudicial y puede llevar a coágulos sanguíneos, accidentes cerebrovasculares y fallo cardíaco.
- 🧴 La vida de un eritrocito es breve, con una expectativa de solo alrededor de 120 días, y su degradación ocurre principalmente en la bazo, hígado y médula ósea.
- 🛠️ La regulación de los niveles de glóbulos rojos es controlada por una hormona especial llamada eritropoyetina (EPO), producida principalmente en los riñones.
- ⚖️ Mantener un balance entre la producción y la destrucción de los glóbulos rojos es crucial para evitar hipoxia o viscosidad excesiva de la sangre.
- 🧪 El proceso de hematopoyesis, que es la formación de las células sanguíneas, comienza en la médula ósea y resulta en la creación de glóbulos rojos maduros listos para entrar en la circulación.
Q & A
¿Qué es la dopaje y cómo está relacionado con el Tour de Francia y Lance Armstrong?
-El dopaje es la utilización de sustancias o métodos prohibidos para mejorar el rendimiento en una competencia deportiva. Está relacionado con el Tour de Francia y Lance Armstrong porque él manipuló su sangre de manera secreta para ganar el Tour de Francia siete veces consecutivas, lo que más tarde se reveló como una práctica de dopaje.
¿Por qué las células sanguíneas son importantes para el cuerpo y cómo están relacionadas con el dopaje?
-Las células sanguíneas, especialmente las glóbulos rojos o eritrocitos, son cruciales para transportar oxígeno a los músculos y al cerebro, permitiendo que el cuerpo funcione adecuadamente. El dopaje se relaciona con ellas porque algunas técnicas de dopaje implican alterar el número o la función de estas células para aumentar la capacidad aeróbica y el rendimiento físico.
¿Cómo es la forma y la función de un glóbulo rojo y cómo esto se relaciona con su vida útil?
-Los glóbulos rojos tienen una forma biconcava, lo que les proporciona una gran superficie para el intercambio de gases y flexibilidad para pasar por capilares estrechos. Esta forma y función les permiten un eficiente transporte de oxígeno, pero su vida útil es corta, con una media de solo 120 días, debido a la rigidez que adquieren con el tiempo y la falta de organelos para reparar su membrana.
¿Cuál es la composición de un glóbulo rojo y cómo esto les permite transportar oxígeno?
-Un glóbulo rojo está compuesto en un 97% por hemoglobina, una molécula que se une fácilmente al oxígeno y se desprende de él. La hemoglobina está formada por heme, un pigmento rojo, y por globina, una cadena de polipeptído. El hierro en el centro del heme es lo que permite a la hemoglobina unirse al oxígeno, y cada glóbulo rojo puede transportar aproximadamente un billón de moléculas de oxígeno.
¿Cómo se producen los glóbulos rojos y cuál es su ciclo de vida?
-La producción de glóbulos rojos, conocida como hematopoyesis, ocurre en la médula ósea roja. Comienza con una célula madre especializada llamada hemocitoblasto, que se diferencia en un eritroblasto temprano. Este produce hemoglobina y, una vez que tiene suficiente, se deshace de la mayoría de sus organelos, adoptando su forma biconcava. Luego se convierte en un reticulócito, que finalmente se convierte en un glóbulo rojo maduro. Estos glóbulos rojos viajan por el cuerpo realizando su trabajo durante unos meses antes de ser reemplazados.
¿Qué es la eritropoyetina (EPO) y cómo regula los niveles de glóbulos rojos en el cuerpo?
-La eritropoyetina (EPO) es una hormona especial que regula los niveles de glóbulos rojos. Se produce principalmente en los riñones y también en el hígado. Cuando los niveles de oxígeno en la sangre disminuyen, ciertas células renales liberan más EPO, lo que estimula la médula ósea para producir más glóbulos rojos. A medida que los niveles de oxígeno aumentan, la producción de EPO disminuye.
¿Cómo se puede manipular el dopaje sanguíneo y cuál es su efecto en el rendimiento físico?
-El dopaje sanguíneo puede realizarse inyectando hormona EPO natural o sintética para aumentar la producción de glóbulos rojos, o bien, extraer y almacenar sangre propia para luego infundirla en el cuerpo después de una pérdida de sangre. Esto aumenta la cantidad de glóbulos rojos, lo que lleva a un mayor transporte de oxígeno a los músculos, reduciendo la fatiga y mejorando la resistencia física.
¿Por qué el dopaje sanguíneo es peligroso para la salud?
-El dopaje sanguíneo es peligroso porque un recuento de glóbulos rojos demasiado alto hace que la sangre se vuelva más espesa, dificultando la circulación y aumentando el riesgo de coágulos sanguíneos, accidentes cerebrovasculares y fallo cardíaco.
¿Cómo es el proceso de reciclaje de los glóbulos rojos viejos y dañados en el cuerpo?
-Los glóbulos rojos viejos y dañados se vuelven rígidos y pueden quebrarse. Son dirigidos a áreas específicas, como el bazo, donde son atrapados y luego son descompuestos por macrofagos blancos sanguíneos. Estos macrofagos reciclan los componentes de los glóbulos rojos, como las proteínas y el hierro, para su reutilización en el cuerpo.
¿Por qué no es recomendable que la hemoglobina circule libremente en la sangre?
-La hemoglobina circulando libremente en la sangre podría hacerlo más espesa y viscosa, lo que obstaculizaría el flujo sanguíneo. Los glóbulos rojos son necesarios para evitar esto, ya que mantienen a la hemoglobina contenida y permiten un transporte eficiente de oxígeno.
¿Qué son los eritrocitos y cuál es su función principal?
-Los eritrocitos, o glóbulos rojos, son las células más abundantes en la sangre y su función principal es transportar oxígeno de los pulmones al resto del cuerpo y luego llevar el dióxido de carbono de vuelta a los pulmones para ser expulsado.
¿Cómo se relaciona la hemoglobina con la capacidad de los glóbulos rojos para transportar oxígeno?
-La hemoglobina es una molécula que compone a los glóbulos rojos y es capaz de unirse y soltar oxígeno fácilmente. Cada molécula de hemoglobina contiene cuatro átomos de hierro, que son esenciales para unirse a las moléculas de oxígeno, permitiendo a cada glóbulo rojo transportar hasta un billón de moléculas de oxígeno.
Outlines
🚴♂️ El peligroso mundo del dopaje
Este párrafo aborda el tema del dopaje, específicamente en el contexto deportivo, y cómo afecta el cuerpo humano. Se menciona a Lance Armstrong como un ejemplo prominente de dopaje en el ciclismo. Se explora la pregunta de por qué el dopaje es considerado trampa y cómo funciona. Además, se destaca el papel fundamental de los glóbulos rojos y su importancia en la distribución de oxígeno en el cuerpo. Se describe la estructura y la breve vida de los glóbulos rojos, y cómo el dopaje puede alterar su función natural, lo que puede llevar a consecuencias negativas para la salud.
🩸 La vida y muerte de los glóbulos rojos
Este párrafo examina el ciclo de vida de los glóbulos rojos, desde su formación en la médula ósea hasta su eventual degradación y eliminación. Se describe el proceso de hematopoyesis y cómo los glóbulos rojos se desarrollan a partir de células madre especializadas. Se destaca la importancia del hemoglobina en la capacidad de los glóbulos rojos para transportar oxígeno. Además, se discute cómo el cuerpo mantiene el equilibrio entre la producción y la destrucción de los glóbulos rojos, y el papel de la hormona EPO en este proceso. Finalmente, se aborda el tema del dopaje sanguíneo, que puede incluir la inyección de EPO o la transfusión de sangre propia, y se mencionan los riesgos asociados con estos métodos para el rendimiento deportivo.
Mindmap
Keywords
💡Doping
💡Eritrocito
💡Hemoglobina
💡Eritropoyetina (EPO)
💡Hematopoiesis
💡Hemoglobina libre
💡Bilis
💡Macrofagos
💡Hipopxia
💡Factor inducible por hipoxia
💡Transfusión autóloga
Highlights
Doping is a dangerous way to enhance physical performance by manipulating one's own blood.
Lance Armstrong is a famous example of an athlete who used blood doping to win the Tour de France seven times.
Erythrocytes, or red blood cells, are crucial for transporting oxygen throughout the body.
Red blood cells make up nearly 45% of blood volume and have a unique biconcave shape that aids in gas exchange.
Erythrocytes lack a nucleus and most organelles, allowing them to focus solely on oxygen transport.
The lifespan of a red blood cell is about 120 days, after which they become rigid and are removed from circulation.
Hemoglobin, which makes up 97% of a red blood cell's dry weight, easily binds and releases oxygen.
Each red blood cell can carry about a billion oxygen molecules thanks to the iron atoms in its hemoglobin.
Free hemoglobin in the blood would make it too viscous and impede blood flow.
Blood doping can involve injecting EPO to boost red blood cell production or re-infusing previously drawn blood.
While doping can enhance endurance by increasing oxygen delivery to muscles, it is dangerous and banned in sports.
High red blood cell counts from doping thicken the blood, making it harder for the heart to pump and risking clots and strokes.
The life cycle of a red blood cell, from formation in the bone marrow to destruction in the spleen, liver, and bone marrow, takes about 120 days.
Erythropoietin (EPO) is a hormone that regulates red blood cell production in response to oxygen levels in the blood.
When blood oxygen levels are low, the kidneys release more EPO to stimulate red blood cell production.
The spleen acts as a 'graveyard' for old red blood cells, where they are broken down and recycled by macrophages.
Iron from hemoglobin is recycled to make new hemoglobin, while the globin proteins are broken down into amino acids.
Doping not only violates the rules of sports, but also poses serious health risks and can lead to severe consequences.
Transcripts
I feel like I haven’t spent nearly enough time lately talking to you about all the stupid
and dangerous things that you can do to your own body, so let’s talk about doping.
You probably have heard of this thanks to Lance Armstrong, who secretly messed with
his own blood so that he could illicitly win the Tour de France seven times in a row.
You might be dimly familiar with the fact that doping isn’t like shooting steroids,
but it is still cheating, even though, like, why is it cheating? And how does it work?
And is it even possible to make your blood better at being blood?
In other words, how can some people treat -- or mistreat -- their own blood like it’s some sort of drug?
Short answer: Because your blood is incredibly powerful stuff.
And its power rests largely in your erythrocytes, or red blood cells. They’re the most abundant
cell type in your blood, accounting for nearly 45 percent of its volume.
Every time you take a breath, they pick up oxygen in your lungs and distribute it through
your body, and then grab carbon dioxide, and bring it back to the lungs where it can be exhaled.
The main mission of erythrocytes is to keep your body fed with oxygen, so your muscles
can do their thing, and your brain can continue to think and feel and boss around your various parts.
But you don’t want to mess around with your red blood cells because erythrocytes are weird characters.
They go places that other cells won’t. They purge themselves of their most precious inner
belongings, preferring instead to live as hollow shells.
Because of the crushing demands of their job, they don’t live very long. And just like
with your blood pressure, too much of these good things can turn bad quickly.
So the erythrocyte must be respected. It is not for doping. Or for dopes.
Despite their prominent role in some international sports scandals, your red blood cells are
fairly simple and unassuming little cells.
They’ve got a distinct biconcave shape -- which just means that they’re concave on both
sides -- making them look kinda like a breath mint… a tiny, bloody breath mint.
And while they have a plasma membrane, they don’t have a nucleus and don’t have most
of the parts other cells do.
So they’re basically just glorified, protein-filled phospholipid-bilayer sacks. But they’re
still another great example of that harmony between form and function.
For one thing, that biconcave shape gives them a large surface area that’s ideal for gas exchange.
It also makes them flexible, able to change shape as they squeeze through tiny capillaries
with diameters smaller than the cell itself.
Of course, all that squeezing and twisting is hard on a cell’s membrane, and that,
combined with their general lack of organelles to help repair the membrane, means these cells
don’t live very long, surviving on average only 120 days.
But they sure work hard while they’re alive.
And their work is mostly in gathering and transporting oxygen. They’re able to do
this because, if you don’t count their water content, red blood cells are 97 percent hemoglobin
-- a molecule that easily binds to, and releases, oxygen. It’s like an oxygen sponge.
Every hemoglobin molecule is really made of eight different component molecules -- four
are a red pigment called heme, and four are a protein called, you guessed it, globin.
Each globin is a globular polypeptide chain -- hence its name -- and proteins, you’ll
probably remember, like to bind to stuff.
So each globin has its own personal ring-shaped heme molecule, and in the center of that heme
is an iron atom, kinda like a cherry on top of a protein-and-pigment sundae.
It’s that iron in the center of the heme that makes our blood red.
Incidentally, not all animals have red blood, because not all animals use hemoglobin to
move oxygen. For example, most mollusks like squids and snails have blue blood, because
it contains hemocyanin, a copper-rich protein-pigment that turns blue when exposed to oxygen.
But, iron is what we’re stuck with, and I have to say it’s great at its job, because
each iron can bind with one whole oxygen molecule.
And that oxygen really adds up.
Since you have four iron atoms in every molecule of hemoglobin and every red blood cell contains
something like 250 million hemoglobin molecules that means each one of your tiny, floppy red-breath-mints
can grab about a BILLION molecules of oxygen.
Exactly how they transfer oxygen and carbon dioxide from your tissue cells is something
that we’ll get into when we talk about the respiratory system.
But if you’re wondering why all this hemoglobin can’t simply skip the red blood cell rigamarole
and just run around naked in your blood, it’s because free-range hemoglobin would actually
thicken the blood, making it so viscous that it would impede blood flow.
This also happens to play a part in blood doping, which -- stick with me -- I will explain in a bit.
So what does the brief but glorious four-month life of an erythrocyte look like? Well, remember
when I said a red blood cell doesn’t have a nucleus? And maybe you thought, hey wait
a second, how can it even be a cell without a nucleus, or DNA?
First of all, nice catch.
But actually, erythrocytes do start off with a nucleus and DNA, they just get rid of them,
because their entire purpose for existing is to schlep around hemoglobin and oxygen,
and they want the extra room.
The whole process of forming blood cells, called hematopoiesis, happens in your red
bone marrow, which is mostly made of reticular connective tissue that’s snuggled up to
special capillaries called blood sinusoids.
In short, the process begins with a hemocytoblast -- or a specialized stem cell -- which soon
differentiates into an early erythroblast. Then, it starts making a whole bunch of ribosomes,
the organelles that manufacture proteins.
And in this case, the ribosomes start cooking up tons of hemoglobin, as the cell transforms
into a late-stage erythroblast.
When it’s got enough hemoglobin, it suddenly jettisons most of its organelles, which causes
the cell walls to collapse a little, giving it its biconcave bloody breath-mint shape.
Now you’re left with a reticulocyte, which is pretty much just an early erythrocyte that
still has a little group of ribosomes left, called a reticulum.
So far, this whole journey so far has taken about fifteen days.
When the reticulocyte is finally bursting with hemoglobin, then it leaves the marrow
and enters the bloodstream, and a couple of days later, when the last ribosomes have degraded,
you’ve officially got yourself a mature red blood cell.
And that cell travels around your body, doing its job for a few months before it gets old
or damaged and needs to be replaced.
Now, maintaining the balance between production and destruction of these cells is crucial.
Too many will make the blood too viscous and difficult to pump,
and too few leads to oxygen deprivation, or hypoxia.
The process of maintaining the right levels of red blood cells is regulated by a special
hormone called erythropoietin, or EPO. It’s produced mostly in the kidneys, but also in
the liver, and is constantly circulating in the blood.
If you’re anemic, or hiking at a high altitude, or hemorrhaging blood, or experiencing anything
else that creates a drop in your blood oxygen levels, certain cells in your kidney will
notice, and take action.
And they can do that, because they traffick in a signaling molecule called hypoxia-inducible
factor, which monitors your blood’s levels of oxygen.
The way that this works is pretty cool. These special kidney cells need oxygen in order
to break down that signaling molecule, so if oxygen levels in the blood are low, they
can’t turn the signal off. This means that the signal keeps going, which triggers the
release of more and more EPO, which stimulates your red bone marrow to pump out more red
blood cells to carry around more oxygen.
As oxygen levels in your blood increase, the signal is degraded, and EPO production slows.
And EPO is a key player in blood doping too, but we’re gonna have to wait a minute before
we get there, because I first want to get back to the fate of your hard-working erythrocytes.
So if you’re generating about two million new blood cells every second, you also have
to dispose of about the same number of dead ones to maintain the balance, right?
When these cells get old, they turn rigid, and their hemoglobins starts to fall apart.
As they get stiffer, they can end up getting stuck in capillaries in your brain or heart,
which would not be good.
Luckily, you have certain channels to corral these dying cells, especially around the spleen,
which some anatomists call “the red blood cell graveyard.”
So these tired old cells get trapped and then basically ambushed by big macrophage white
blood cells in the spleen, liver, and bone marrow, which break them down and recycle
their various components.
The globin proteins are broken down into their basic components -- amino acids -- which go
back into the blood to be used by other cells for making more proteins.
Iron from the heme group is separated and either bound to proteins and stored in the
liver, or put right back into a new hemoglobin molecule. And the heme gets turned into bilirubin,
a yellowish pigment that goes to the liver where it’s added to the bile that it secretes
into the intestine and eventually leaves the body in your poop.
Now that you know how your erythrocytes function naturally, it’s easier to see how they can
be messed with -- often with bad results.
You can dope your blood in a few different ways, but the most common technique is to
inject natural or synthetic EPO hormone to boost your red blood cell production.
It’s also possible to draw and store some of your own blood, and then transfuse it back
into your body after your body has recovered from the blood loss, effectively raising your
volume of red blood cells.
The logic, if you can call it that, is that more red blood cells equals more oxygen being
carried to your muscles, and therefore better physical performance.
Now, the extra oxygen can’t change your actual muscle strength, but the added aerobic capacity
does reduce muscle fatigue and enhance endurance, by allowing your muscles to work harder for longer.
And it can provide enough of an extra edge to win a race, like, say, the Tour de France.
Seven times.
But not only is it banned in athletic competitions, blood doping is also dangerous.
Because, remember, a red blood cell count that’s too high thickens the blood, and
that actually makes it harder for the heart to pump blood around the body. In addition
to defeating the purpose of enhancing the blood’s effectiveness, this can lead to
blood clots, and strokes, and heart failure. So, no thank you.
Plus, cheating sucks.
But today you learned about the structure and function of your erythrocytes, and of
hemoglobin, which they use to carry oxygen. We also went through the formation and life
cycle of a red blood cell, and studied how their levels are regulated by EPO and their
signalling molecules. Finally, we learned how doping the blood is a recipe for disaster
and for finding yourself on Oprah and apologizing to everyone you know and losing all of your yellow jerseys.
Thanks to all of our Patreon patrons who help make Crash Course possible for themselves
and for everyone for free with their monthly contributions. If you like Crash Course and
want to help us keep making videos like this one, you can go to patreon.com/crashcourse.
This episode was filmed in the Doctor Cheryl C. Kinney Crash Course Studio, it was written
by Kathleen Yale, the script was edited by Blake de Pastino, and our consultant is Dr.
Brandon Jackson. It was directed and edited by Nicole Sweeney; our sound designer is Michael
Aranda, and the graphics team is Thought Cafe.
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