What Are the Components of Blood?

Summary

This video script delves into the composition and critical functions of human blood, highlighting its diverse cellular makeup including red blood cells, white blood cells, and platelets. It explains how blood's components, such as plasma's dissolved substances, serve various physiological needs and can indicate health issues. The script also touches on the emerging role of blood biomarkers, like microRNA, in early cancer detection and prognosis, emphasizing blood's vital role in both our body's functions and disease diagnosis.

Takeaways

• 🩸 The average adult human body contains about 5 liters of blood.
• 🌟 Blood is not a uniform fluid but a complex mixture of various substances, including cells and plasma.
• 🧬 Plasma, the light yellow top layer, is mostly water but contains dissolved solids like proteins, sugars, and hormones.
• ❤️ Red blood cells, or erythrocytes, are the most abundant cells in blood, making up about 40% of blood volume.
• 🔬 White blood cells, or leukocytes, and platelets are found in the middle layer and play crucial roles in immune response and blood clotting.
• 🌐 The term '-cyte' indicates a mature cell, with 'erythro-' meaning red and 'leuko-' meaning white.
• 🤒 White blood cells, including lymphocytes and granulocytes, patrol the body for signs of injury or infection.
• 🩹 Platelets initiate blood clotting when they encounter an injury, helping to form scabs if the injury is on the skin.
• 🚑 Red blood cells transport oxygen throughout the body, facilitated by the protein hemoglobin.
• 🧪 Blood tests can reveal health information, such as cholesterol levels, and can be used to diagnose conditions like diabetes.
• 🔍 Biomarkers in the blood, like microRNA, can indicate the presence of diseases and predict health outcomes, including certain types of cancer.

Q & A

How much blood is typically found in the human body?

Approximately 5 liters of blood is found in the human body.

What are the three distinct layers that emerge when blood is allowed to sit or spun in a centrifuge?

The three distinct layers are plasma on top, erythrocytes (red blood cells) at the bottom, and in the middle, a layer containing leukocytes (white blood cells) and platelet cells.

What is plasma and what is its primary component?

Plasma is the lightest, creamy colored layer of blood and is mostly composed of water. It contains dissolved solids such as proteins, sugars, hormones, and other substances.

What is the primary function of erythrocytes or red blood cells?

The primary function of erythrocytes is to ferry oxygen through the blood to the rest of the body.

How do red blood cells carry oxygen?

Red blood cells carry oxygen through a protein called hemoglobin, which is made up of iron and four globin proteins. Oxygen molecules bind to these hemoglobin proteins.

What is the significance of the shape and structure of red blood cells?

Red blood cells are donut-shaped and squishy, which gives them more surface area for oxygen to seep through and allows them to fit through the tiniest blood vessels without clogging them.

What are the different types of white blood cells mentioned in the script?

The script mentions B and T cells (collectively called lymphocytes), granulocytes, and monocytes which can become macrophages.

What is the role of platelets in the blood?

Platelets initiate the process of blood clotting when they encounter an injured blood vessel. On the skin, this clot is known as a scab.

How can blood tests provide valuable health data?

Blood tests can measure substances like cholesterol, triglycerides, and glucose levels, which can indicate health conditions such as diabetes or kidney disease.

What are biomarkers and how are they used in healthcare?

Biomarkers are biological markers found in the blood that can provide clues for doctors to make better diagnoses or predict outcomes. They can indicate the presence of diseases or health conditions.

How can microRNA in blood be used for medical purposes?

MicroRNA are genetic material fragments that can be measured in the blood to predict a person's risk of specific cancers, potentially allowing for earlier detection and more precise treatment.

Outlines

00:00

🩸 Blood Composition and Functions

This paragraph introduces the concept of blood and its importance to human physiology. It explains that blood is not a uniform fluid but consists of multiple substances with different purposes. Blood is composed of plasma, red blood cells (erythrocytes), white blood cells (leukocytes), and platelets. Plasma is mostly water but contains dissolved solids like proteins, sugars, and hormones. Red blood cells are the most common cells in blood, making up about 40% of its volume, and are responsible for carrying oxygen throughout the body. White blood cells are less common but crucial for the immune system, and platelets are cell fragments that help in blood clotting. The paragraph also touches on the terminology of blood cells, explaining that the suffix '-cyte' denotes a mature cell, with prefixes indicating color.

05:02

🧬 Blood Tests and Biomarkers

This paragraph discusses the role of blood tests in predicting disease risk and diagnosing health conditions. It mentions that blood tests can measure various substances dissolved in plasma, such as cholesterol and blood sugar levels, which can indicate conditions like diabetes. The concept of biomarkers is introduced, which are small compounds in the blood that can provide clues about diseases throughout the body. The paragraph highlights how advances in medical testing allow for the detection of these biomarkers, such as microRNA, which can be used to predict the risk of specific cancers. It also mentions how blood tests can be used to diagnose concussions with greater accuracy by measuring biomarkers. The paragraph concludes by noting that the next video will cover blood typing and the potential for creating a universal blood donor type.

Keywords

💡Blood

Blood is a vital fluid in the circulatory system of humans and other vertebrates, consisting of plasma, red blood cells, white blood cells, and platelets. In the video, blood is described as a substance holding clues to various diseases and is the focus of the episode, which aims to introduce the audience to the different components of blood and their functions.

💡Red Blood Cells (Erythrocytes)

Red blood cells are the most common cells in the blood, making up about 40% of its volume. They are responsible for carrying oxygen throughout the body. The video mentions that these cells are donut-shaped and contain hemoglobin, which gives them their red color and allows them to transport oxygen efficiently.

💡White Blood Cells (Leukocytes)

White blood cells are a crucial part of the immune system and are found in the middle layer of blood when separated. They are less numerous than red blood cells but play a vital role in fighting infections. The video explains that there are different types of white blood cells, including lymphocytes and granulocytes, which respond to signals like interleukin-1 and histamine.

💡Plasma

Plasma is the liquid component of blood, making up the top layer when blood is separated. It is mostly water but contains dissolved substances like proteins, sugars, and hormones. The video likens plasma to hot cocoa, emphasizing that it is the substances dissolved in it that give it its importance.

💡Hemoglobin

Hemoglobin is a protein in red blood cells that contains iron and is responsible for binding and transporting oxygen. The video explains that the presence of hemoglobin allows red blood cells to carry oxygen throughout the body and is what gives blood its red color.

💡Platelets

Platelets are cell fragments that play a role in blood clotting. When an injury occurs, platelets aggregate at the site to form a clot, which can be seen as a scab on the skin. The video describes platelets as wandering without purpose until they encounter an injury, at which point they initiate the clotting process.

💡Biomarkers

Biomarkers are measurable substances in the blood that can indicate normal or disease processes. The video discusses how biomarkers, such as micro RNA, can be used to predict the risk of diseases like cancer, allowing for earlier detection and more precise treatment.

💡Micro RNA

Micro RNA are small genetic molecules that can be found in the blood and can indicate the presence of certain diseases. The video gives the example of microRNA-21, which can be an indicator of colorectal cancer, and microRNA-141, which can be associated with survival rates.

💡Concussions

A concussion is a type of traumatic brain injury. The video mentions that biomarkers now exist that can help diagnose concussions, improving the accuracy of diagnosis and allowing doctors to measure the severity of the injury.

💡Blood Typing (ABO)

Blood typing is the method of classifying blood into groups based on the presence of certain antigens. The ABO blood group system is one such classification system. The video alludes to the next episode covering how this system works and advancements towards creating a universal blood donor type.

💡Immune System

The immune system is a complex network of cells, tissues, and organs that work together to defend the body against infections and diseases. The video discusses how white blood cells are a part of the immune system and are vital for responding to injury or infection.

Highlights

The average human body contains about 5 liters of blood.

Blood is a complex substance with multiple components, not just a uniform fluid.

Blood separates into three distinct layers when left to settle or centrifuged: plasma, red blood cells, and white blood cells.

Plasma is mostly water but contains dissolved solids like proteins, sugars, and hormones.

Red blood cells, or erythrocytes, are the most common cells in blood and make up about 40% of its volume.

White blood cells, or leukocytes, and platelets make up less than 1% of blood volume but play crucial roles in immunity and clotting.

The term '-cyte' indicates a mature cell, with 'erythro-' meaning red and 'leuko-' meaning white.

There are various types of white blood cells, including lymphocytes and granulocytes.

White blood cells are part of the immune system, responding to signals like interleukin-1 and histamine.

Platelets initiate blood clotting when they encounter an injury.

Red blood cells transport oxygen throughout the body due to the presence of hemoglobin.

Hemoglobin is composed of iron and globin proteins, which give red blood cells their color.

Red blood cells are optimized for oxygen transport, being small, flexible, and lacking a nucleus.

Blood tests can reveal health information such as cholesterol, triglycerides, and glucose levels.

Biomarkers in blood can predict disease risk and aid in diagnosis.

MicroRNA in blood can be used as a biomarker for specific cancers, potentially improving early detection and treatment.

Blood typing, such as the ABO system, will be discussed in a future video, along with advances towards universal donor blood.

Biomarkers are also being used to diagnose and measure the severity of concussions.

Transcripts

Take a guess as to how much blood is in your body right now? Just like a ballpark guess.

Think about all the blood in your heart, all the blood in your arteries, veins, and all

the smaller blood vessels. Add up all those sources of blood and you get 5 whole liters. That’s

about this much! This glorious red stuff is so valuable to our physiology as humans, that

we’re going to spend an entire episode introducing you to the cast of characters that make blood

what it is.

For instance, you’ve probably heard about the big players like red blood

cells and white blood cells, but blood is a diverse and multi-faceted substance that

also holds clues to diseases that affect more than just your blood. I want you to think

back to the last time you got a cut. The blood that oozed out of that cut was probably bright

red, shiny and dripped quite a bit more slowly than water. That may give you the impression

that blood is a uniform fluid, but it’s actually multiple substances, all with different

purposes. You can tell because if you look at a vial of blood and let it sit around for

a few hours or if you spun it in a centrifuge, you’d notice three distinct layers emerge

as the denser components of blood sank to the bottom. The creamy colored and lightest

layer on top is the plasma, which is mostly water. But just like a mug of hot cocoa, it’s

what you dissolve in the water that makes it interesting. Yes, I made my cocoa with

water growing up. All you kids who made your hot cocoa with milk, it must be nice.

Plasma is where you’ll find the dissolved solids in your blood. Substances like proteins,

sugars, hormones, and a ton of other things. The red, dense layer at the bottom is made

of erythrocytes, also known as red blood cells, the most common type of cell found in your

blood. We’re talking around 250 million cells per drop of blood. That takes up about

40% of your blood by volume. Which leaves this little layer in the middle here making

up less than 1% of your blood volume. This is where you’ll find your leukocytes, or

white blood cells alongside platelet cells. And even though they only make up a tiny volume

of blood, these cells still have an important function that all comes back to our immune

system. Now, you’ll notice that a lot of cell names we’ve been talking about so far

end in -cyte, which is no coincidence. Whether it’s an erythrocyte or a leukocyte, -cyte

denotes a mature cell. And the prefixes here literally mean red and white. So basically

we have these fancy words that translate back to red cell and white cell. Now, we do still

have a handful of different leukocytes — there isn’t just one single type of white blood

cell. Like B and T cells, what are collectively called lymphocytes are just two types of white

blood cell. If you want to learn more about those cells by the way, we’ll dive into

them and the immune response later in the playlist. Other white blood cells include

a diverse group of immune cells called granulocytes, as well as monocytes which become big chunky-boy

cells called macrophages. Collectively, white blood cells float around in circulation waiting

for some kind of signal that recruits them to the scene of injury or infection. That

signal might be a chemical like interleukin-1 that plays a part in fever, or histamine which

you’re familiar with if you’ve ever sought allergy relief. Now, it might seem surprising

that there are so many immune cells in your blood. After all, there’s a whole separate

immune system for this exact purpose, right? Well, if you want to constantly patrol the

body to find something, traveling through the blood is actually a good strategy. Take

the other component in that little sliver of blood for example, platelets. These little

cell fragments travel through the blood until they bump into an injured blood vessel. And

at that time they start the process of making a blood clot. If this injury took place on

your skin, this blood clot might be better known as a scab. Just like that one Blink

182 song, platelets wander around with no purpose or direction, and they don’t owe

us a single explanation.

So white blood cells help protect us, platelets

clot our blood after an injury, but what do red blood cells do? These donut shaped cells

are squishy, bendable cells with one main purpose — ferry oxygen through the blood

to the rest of the body. And these things are tiny, only 6 microns wide. That’s a

good thing too, because they need to fit through the tiniest blood vessels in the body without

clogging them shut. Red blood cells can carry oxygen because they contain a protein called

hemoglobin, made up of iron, which is the heme- part, and four globin proteins, hence

globin. Oxygen molecules bind onto those hemoglobin proteins so they can hitch a ride

through the bloodstream. All those iron molecules give red blood cells their color too. Just

like how Mars has a bunch of iron on its surface and looks red, it’s the same iron atoms

coloring our blood. And these cells are totally optimized to carry oxygen, or to be oxygenated.

In mammals, red blood cells don’t have a nucleus, which gives them more space for hemoglobin.

And their donut shape gives them more surface area for oxygen to seep through. Plus, oxygen

binds to this protein in a way that when one oxygen molecule binds to hemoglobin, it becomes

easier for more oxygen molecules to hop on that same hemoglobin afterwards. And as those

oxygenated red blood cells are pumping through your arteries, they’ll drop off some oxygen

at active tissues or anywhere in the body that oxygen is needed. Now, red and white

blood cells are the major cells in our blood, and can tell us a lot about our health. But

that other stuff, all the substances dissolved in the plasma can also give us valuable health

data. Like if you go in for a check up and your doctor orders a blood test, they’ll

probably measure things like cholesterol, triglycerides, midichlorians. The usual. There

are definitely times they’d want to measure red and white blood cell counts, but a lot

of the substances you’re used to hearing about are dissolved in plasma. And one of

the ways to use that information is to predict your risk of disease. For example, a fasted

blood sugar test is one of the things doctors might use to diagnose diabetes. This test

is built on the idea that people with diabetes may have elevated levels of glucose in their

blood compared to non diabetics. But all kinds of blood tests can tell us different things

about your health. Like measuring blood electrolytes can give us information about kidney disease,

and counting the number of white blood cells can tell us the status of the immune system.

But doctors’ tests are getting sensitive and specific enough to find all kinds of really

small compounds in the blood that can give them hints about diseases elsewhere in the

body. And not just for body parts directly in the circulatory system, but all over. These

compounds are called biomarkers, literally biological markers. They can be used as clues

for doctors to make better diagnoses, or to predict outcomes more accurately. Now, technically,

metrics like pulse and blood pressure count as biomarkers but scientists are finding all

kinds of new biomarkers in the lab that can help them make decisions about health care.

For example, scientists can measure extremely tiny fragments of genetic material in someone’s

blood called micro RNA and make predictions about that person’s risk of specific cancers. Here’s

what’s cool and exciting about that though — for just about every form of cancer, the

outcomes are much better if the disease is recognized and treated early, or prevented

altogether. And microRNA are very specific to cell type and disease states, so they can

give us very precise information about someone’s cancer diagnosis and where to look. So this

biomarker in your blood might give doctors the ability to detect certain cancers earlier

and target therapies more precisely. Take one of the deadlier forms of cancer, colorectal

cancer. Scientists noticed that if they found a type of microRNA called microRNA-21 in someone’s

blood, there was a very good chance that person had colorectal cancer. Or if they had more

of microRNA-141, participants tended to have a worse chance of survival, which means this

biomarker could give doctors a more accurate prognosis. So not only does blood carry out

so many important functions for our survival, it can give us clues about diseases that may

help us survive longer. But we left out a pretty important detail in this video. You

know that whole ABO blood typing thing? Well, our next video will get you up to speed on

how that system works, and how we’re getting close to turning everyone’s blood into the

universal donor type. Speaking of biomarkers, I’ve had a few concussions throughout my

youth, and every time, doctors ordered a CT scan for me. These days, a few biomarkers

exist for diagnosing concussions, which not only improves diagnosis accuracy but lets

doctors objectively measure how severe the concussion is.  I’m Patrick Kelly, thanks

for watching this episode of Seeker.