Respiration Gas Exchange

Summary

This video covers the process of gas exchange in the human body, focusing on how oxygen and carbon dioxide are transported. It explains the journey of deoxygenated blood returning to the heart, traveling through the lungs to release carbon dioxide, and becoming re-oxygenated. The video also explores the role of hemoglobin in oxygen transport, carbon dioxide transport methods, and the relationship between carbon dioxide levels and blood pH. Finally, it touches on oxygen saturation levels and the importance of maintaining them for proper body function.

Takeaways

• 🌬️ Gas exchange involves the transportation of oxygen and carbon dioxide throughout the body via the lungs, heart, and tissues.
• 🫁 Deoxygenated blood, which contains higher concentrations of carbon dioxide, returns to the heart through the vena cava and is pumped to the lungs through the pulmonary artery.
• 💨 In the lungs, deoxygenated blood offloads carbon dioxide and absorbs oxygen, becoming oxygenated blood, which then returns to the heart through the pulmonary vein.
• 🫀 The heart pumps oxygenated blood through the aorta, arteries, and arterioles, eventually reaching tissues where oxygen is offloaded, and carbon dioxide is taken up.
• 🌡️ Partial pressures of oxygen and carbon dioxide in tissues and blood dictate the movement of these gases during exchange processes.
• 🩸 Oxygen is primarily transported in the blood bound to hemoglobin in red blood cells, while a small portion is dissolved in plasma.
• ⚛️ Carbon dioxide is mainly transported as bicarbonate in plasma, with smaller amounts bound to hemoglobin and dissolved in plasma.
• 🔄 Carbon dioxide and pH levels are closely related, with increases in carbon dioxide causing a drop in pH, making blood more acidic.
• 🧪 In the lungs, carbon dioxide in the blood is released into the alveoli for exhalation, and oxygen is absorbed into the blood to form oxyhemoglobin.
• 📊 Oxygen saturation refers to the concentration of oxygen in the blood, with normal levels being 95-100%.

Q & A

What is the primary focus of the video?

The primary focus of the video is explaining the process of gas exchange in the body, specifically how oxygen and carbon dioxide are transported between the lungs, heart, and tissues.

How does deoxygenated blood return to the heart?

Deoxygenated blood returns to the heart via venules and veins, entering either through the inferior or superior vena cava.

What happens to deoxygenated blood in the lungs?

In the lungs, deoxygenated blood offloads carbon dioxide and gets re-oxygenated as it takes in oxygen, becoming oxygenated blood.

How is most oxygen transported in the body?

Most oxygen is transported in the body bound to hemoglobin in red blood cells, where it can disassociate and be used by tissues.

What are the three mechanisms by which carbon dioxide is transported in the blood?

Carbon dioxide is transported in three ways: dissolved in plasma (10%), bound to hemoglobin as carboaminohemoglobin (20%), and as bicarbonate in plasma (70%).

What role does carbonic anhydrase play in carbon dioxide transport?

Carbonic anhydrase is an enzyme in red blood cells that facilitates the fast conversion of carbon dioxide and water into bicarbonate and hydrogen ions.

How does carbon dioxide affect blood pH levels?

An increase in carbon dioxide leads to a higher concentration of hydrogen ions, which decreases blood pH and makes the blood more acidic. Conversely, a decrease in carbon dioxide increases pH, making the blood more alkaline.

What happens during gas exchange in the alveoli?

In the alveoli, carbon dioxide is transported from the blood to the alveolus to be exhaled, while oxygen is inhaled and enters the bloodstream, primarily binding to hemoglobin in red blood cells.

What is oxygen saturation and why is it important?

Oxygen saturation refers to the concentration of oxygen in the blood. It is important because it indicates how well oxygen is being transported to tissues, with normal levels ranging from 95% to 100%.

What is the next topic the video will cover?

The next video will cover the control of respiration, which likely involves the regulation of breathing and gas exchange.

Outlines

00:00

🔬 Introduction to Gas Exchange in the Body

This paragraph introduces the video topic of gas exchange, focusing on how oxygen and carbon dioxide are transported throughout the body. It begins with the function of the lungs and heart, describing how deoxygenated blood travels to the lungs to release carbon dioxide and gain oxygen. The blood's journey continues as oxygenated blood is pumped back to the heart and then delivered to tissues through arteries, arterioles, and capillaries. The focus is on how oxygen is used by tissues and carbon dioxide is produced as a byproduct, which reenters the bloodstream for removal.

05:00

🌬 Transport of Carbon Dioxide in the Blood

This section explains how carbon dioxide, produced as a byproduct in tissues, enters the bloodstream for transport. It describes three main ways CO2 is carried: dissolved in plasma, converted into bicarbonate, and attached to hemoglobin. The majority of CO2 is converted into bicarbonate via a fast reaction catalyzed by carbonic anhydrase in red blood cells. The paragraph also covers the chloride shift mechanism that balances the exchange of bicarbonate and chloride ions in the blood. Lastly, it discusses the relationship between carbon dioxide and blood pH, where increased CO2 lowers pH, making the blood more acidic.

10:02

🫁 Gas Exchange at the Alveoli

This paragraph dives into the process of carbon dioxide offloading from the blood into the alveoli of the lungs, where it can be exhaled. CO2 is carried in several forms, such as bicarbonate, which reacts with hydrogen ions to form CO2 again. This process occurs quickly in red blood cells due to the enzyme carbonic anhydrase. Additionally, some CO2 is released directly from hemoglobin. After CO2 is removed, oxygen is inhaled and enters the bloodstream, where it binds to hemoglobin or dissolves in plasma. Oxygen transportation is primarily handled by hemoglobin, with only a small fraction dissolved in plasma.

Keywords

💡Gas exchange

Gas exchange refers to the process by which oxygen is taken into the body and carbon dioxide is expelled. In the context of the video, it explains how oxygen is delivered to tissues and carbon dioxide is transported to the lungs for exhalation. The main focus is on how this occurs in the lungs (alveoli) and circulatory system (blood vessels).

💡Deoxygenated blood

Deoxygenated blood is blood that has low oxygen content and high levels of carbon dioxide. The video explains how blood returns to the heart after oxygen has been used by tissues and how it is then pumped to the lungs to release carbon dioxide and take up fresh oxygen.

💡Pulmonary circulation

Pulmonary circulation is the movement of blood from the heart to the lungs and back to the heart. In the video, it describes how deoxygenated blood travels from the heart to the lungs through the pulmonary artery and returns as oxygenated blood via the pulmonary vein.

💡Hemoglobin

Hemoglobin is a protein found in red blood cells that binds to oxygen. In the video, it is explained that most oxygen in the blood is transported bound to hemoglobin, which releases oxygen into tissues where it is needed for energy production.

💡Bicarbonate

Bicarbonate is a form in which carbon dioxide is transported in the blood. The video details how carbon dioxide reacts with water to form bicarbonate in the blood, which helps maintain pH balance and is a major way carbon dioxide is carried to the lungs for exhalation.

💡Partial pressure

Partial pressure refers to the concentration of a gas in a mixture of gases. The video uses this concept to explain how oxygen and carbon dioxide are exchanged between the blood and tissues based on differences in their partial pressures in different parts of the body.

💡Alveoli

Alveoli are tiny air sacs in the lungs where gas exchange occurs. The video explains how carbon dioxide leaves the blood and enters the alveoli, and how oxygen moves from the alveoli into the blood, facilitated by a thin membrane for efficient gas diffusion.

💡Oxygen saturation

Oxygen saturation refers to the percentage of hemoglobin molecules that are bound to oxygen. The video explains that normal oxygen saturation levels should be between 95% and 100%, indicating efficient oxygen transport in the blood.

💡Carbonic anhydrase

Carbonic anhydrase is an enzyme found in red blood cells that speeds up the conversion of carbon dioxide and water into bicarbonate and hydrogen ions. The video explains its role in accelerating carbon dioxide transport in the blood.

💡Respiration

Respiration is the process by which the body takes in oxygen and expels carbon dioxide. In the video, it is explained in two contexts: cellular respiration (using oxygen for energy) and pulmonary respiration (gas exchange in the lungs).

Highlights

Introduction to gas exchange in the body, focusing on oxygen and carbon dioxide transportation.

Deoxygenated blood returns to the heart after tissues use oxygen, entering through the inferior or superior vena cava.

The heart pumps deoxygenated blood through the pulmonary artery to the lungs, where it offloads carbon dioxide.

Oxygenated blood returns to the heart via the pulmonary vein, ready to be distributed to the tissues.

Red blood cells play a major role in oxygen transport by binding oxygen to hemoglobin.

Oxygen dissociates from hemoglobin, enters tissues through plasma or interstitial fluid, and is used as energy.

Carbon dioxide, a byproduct of metabolism, is transported back to the lungs in various ways, including plasma and as bicarbonate.

The enzyme carbonic anhydrase in red blood cells speeds up the conversion of carbon dioxide and water into bicarbonate.

Carbon dioxide is transported as bicarbonate in plasma (70%), bound to hemoglobin (20%), and dissolved in plasma (10%).

Carbon dioxide and pH levels are closely linked; an increase in carbon dioxide lowers pH, making the blood more acidic.

In the lungs, carbon dioxide is exhaled and oxygen is inhaled, leading to gas exchange at the alveolar level.

Oxygen is primarily transported bound to hemoglobin in red blood cells (98%); a small amount is dissolved in plasma (2%).

The majority of carbon dioxide in the blood is transported in the form of bicarbonate via fast processes inside red blood cells.

Oxygen saturation refers to the concentration of oxygen in the blood, with normal levels being 95-100%.

The next video will focus on the control of respiration, expanding on the mechanisms discussed in gas exchange.

Transcripts

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in this video we're going to look at gas

exchange so essentially we're looking at

how gases are transported around our

body the oxygen and carbon dioxide and

how our tissues receive this oxygen in

our lungs receive the carbon dioxide so

we can exhale it so let's just begin

this journey with the lungs here and

here I'm drawing the heart as well and

also tissues

so here is our tissue our heart and our

lungs after the tissue has utilized or

used oxygen the blood return will then

return to the heart the blood returning

to the heart is deoxygenated blood

because it contains you can say low

oxygen the oxygen has been used by the

tissue now the blood leaving the tissues

in order will be venules veins and then

as it enters the heart it can either

enter through the inferior or superior

vena cava so will enter the heart and

then from the heart the heart will pump

this deoxygenated blood through the

pulmonary artery so why is it called

deoxygenated blood well it's because we

have more concentration you can say of

carbon dioxide compared to oxygen or

it's properly said we have a higher

partial pressure of carbon dioxide

compared to oxygen that is why they are

deoxygenated as a deoxygenated blood

enters the lungs it will the blood will

offload the carbon dioxide and then the

lungs will re oxygenate the blood

essentially putting in more oxygen into

the blood forming oxygenated blood and

this oxygenated blood supply will then

go back to the heart through the

pulmonary vein so if we look at the

partial pressure of oxygen and carbon

dioxide again we can see that we have

higher amounts of oxygen compared to

carbon dioxide

so as this pulmonary vein brings this

oxygenated blood back to the heart

the heart can then pump this oxygenated

blood to tissues or around our body

first of all through the aorta then the

arteries then the arterioles where the

arterioles will then form capillaries

and then in and then into tissues and if

we look at the partial pressure of gases

in this oxygenated blood supply we can

see that we have

higher amounts of oxygen compared to

carbon dioxide and so within the tissues

again we have oxygen being offloaded

into the tissues so the tissue can use

it as energy and then carbon dioxide

release back into the blood as a

by-product and within the tissues if we

look at the partial pressure of the

gases we have slightly higher amounts of

carbon dioxide compared to oxygen carbon

dioxide and oxygen are transported

mostly within red blood cells now let's

zoom into this area here and see how the

red blood cells

offloads the oxygen to the tissues and

how the tissues will then offload the

carbon dioxide back to the blood and how

carbon dioxide is transported so zooming

into this area here we have the tissues

are the cells of the tissue and here I'm

drawing the lining of the blood vessel

so in red here this means that this is

here is the blood and here is the

interstitial fluid

let us firstly look at how oxygen enters

the tissue some oxygen can be dissolved

in plasma and can enter the interstitial

fluid and then can enter the tissue

where the tissue can utilize it as

energy

however most oxygen in our body is

transported in red blood cells

such as this one I am drawing here

oxygen is transported bound to a

molecule known as hemoglobin HB so here

is hemoglobin oxygen bound to hemoglobin

the hemoglobin and oxygen can

disassociate forming hemoglobin and

oxygen gas this oxygen can then enter

the interstitial fluid and then oxygen

can be used by the tissue okay

so that was the two ways oxygen enters a

tissue from the blood now let's look at

carbon dioxide because the tissues form

carbon dioxide as a by-product after

using oxygen

some of the carbon dioxide a little very

little amount can actually just enter

the blood and just be transported

through plasma some of it can re-enter

the blood react with water and through a

slow process form bicarbonate and

hydrogen ions and so carbon dioxide in

this case is being transported as

bicarbonate

however most of the carbon dioxide will

actually enter the red blood cells and

then here it will react with water

within red blood cells you have these

membrane bound enzymes called carbonic

anhydrase which will through a fast

process convert carbon dioxide and water

to form bicarbonate and hydrogen ion

exactly the same as the process that

occurred outside which was slow and then

bicarbonate can then be trying to pumped

out by the red blood cell into the

actual plasma and so be transported as

bicarbonate the transporter will take

bring in a chloride ion in exchange the

hydrogen ion here can react with the

hemoglobin molecule within the red blood

cell to form on the hydrogen hemoglobin

and then you have another mechanism

where the carbon dioxide can enter the

red blood cell and actually attach with

hemoglobin to form carbo amino

hemoglobin

so now if we will look if we're going to

look at the waste carbon dioxide is

transported in the blood we can we know

that there are at least three mechanisms

the first is that carbon dioxide can

dissolve in plasma about 10 percent of

it which is this one or carbon dioxide

can react with a hemoglobin within red

blood cells to form carbon Carboni amino

hemoglobin and this is about 20% of the

carbon dioxide being transported this

way and the last which is the majority

which is the major mode of

transportation for carbon dioxide is as

bicarbonate in plasma and this is about

70% of the carbon dioxide but again

forming bicarbonate there are two ways

one is that it can be formed in red

blood cells which is a fast process or

it can be formed in the plasma itself

which is much slower now it's also

important to understand that carbon

dioxide and pH is also very much related

if we have an increase in carbon dioxide

this will actually cause a decrease in

pH which means that it will make the

blood acidic if we have a decrease in

carbon dioxide this will make the blood

much more alkaline so an increase in pH

why is this well first of all let's just

pretend that we have more carbon dioxide

if we have more carbon dioxide this will

shift the reaction to form more

bicarbonate and hydrogen ions if we have

more hydrogen ions this just means that

it will be more acidic so that was

looking at how carbon dioxide gets

transported now let's look at how carbon

dioxide gets offloaded and then how

oxygen is transported in a bit more

detail so let's buy to look at this

let's let's go back to the lungs here

and zoom in the lungs are made up of

branches of bronchioles

and the ends of them called alveoli or

alveolar sac so the L vo this is cluster

of lvl alveoli they have blood supply

essentially the pulmonary artery coming

in and then the pulmonary vein leaving

so let us zoom into this area here where

gas exchange takes place within the

alveoli so here I'm drawing the cell

lining of one alveoli which is known as

an LV olace and then here I'm drawing

the boundary of the blood vessel and

here we can find the red blood cell so

here is the alveolus here is the blood

with the red blood cell and here's just

a fused membrane which is a thin gap

before we continue we have to understand

that the alveolus is the lung so it is

what it is a structure that receives the

carbon dioxide and that offloads oxygen

into the blood so let's first begin by

looking at how carbon dioxide is

transported from the blood back into the

alveolus into the lungs so that we can

exhale the carbon dioxide so if you

remember the previous diagram some of

the carbon dioxide is transported

through plasma so this carbon dioxide

can just enter the alveolus a majority

of the carbon dioxide is actually

transported if you remember in the blood

as bicarbonate and so this bicarbonate

can react with hydrogen ions in the

blood and through a slow process form as

an end product carbon dioxide and water

the carbon dioxide can then just enter

the alveolus of course some of this

actually a lot of it or however much of

this bicarbonate in plasma can actually

enter the red blood cells through a

transporter which will bring out

chloride ion an exchange within the red

blood cell bicarbonate can

react with hydrogen ion and through a

fast process and with the help of the

enzyme carbonic anhydrase the

bicarbonate hydrogen reaction can form

the carbon dioxide and water and it's

fast compared to the outside because of

an enzyme present and then this carbon

dioxide can then just exit the red blood

cell and enter the alveolus finally you

remember that some of the carbon dioxide

is transported in the blood bound to

hemoglobin as carbo amino hemoglobin and

so this will disassociate and then the

carbon dioxide after it's disassociated

with hemoglobin can then enter the

alveolus ok so now we have a lot of the

carbon dioxide in the alveolus our body

will our lungs will exhale this carbon

dioxide and then we'll inhale oxygen so

oxygen enters the alveolus and then

oxygen can be transported via two ways

small amount of oxygen will be

transported in plasma just enters the

plasma however most of the oxygen will

actually enter the red blood cell and

then bind to hemoglobin well hydrogen

bound hemoglobin and then this will form

essentially your oxyhemoglobin and so

this hydrogen ion will is the hydrogen

ion that supplies the bicarbonate

reaction here so again just to stress

what I'm trying to say oxygen transport

occurs through two ways it can be

dissolved in plasma which this is less

than 2% of oxygen is transported this

way most of the oxygen is bound to

hemoglobin which is 98% plus and this

brings us to the last concept which is

called oxygen saturation now oxygen

saturation is a kind of an important

term to know because it's essentially

referring to the concentration of oxygen

in the blood and normal blood oxygen

levels normal blood

oxygen saturation levels should be at

least 95 to 100 percent thank you for

watching hope you enjoyed this video on

gas exchange the next video we will look

at is control of respiration

you