Respiratory System | Structure and Function

Summary

The video introduces the basics of the respiratory system, starting with a practice of breathing, followed by an explanation of how it works. It covers key components like the nasal cavity, nasal concha, and olfactory bulb, explaining how air is warmed, humidified, and filtered. The video discusses sinuses, the function of the uvula, and how the epiglottis prevents food from entering the trachea. The anatomy of the trachea, lungs, and diaphragm is explained, highlighting the gas exchange in the alveoli and the importance of the rib cage and pleural membrane in protecting the lungs.

Takeaways

• 🌬️ The respiratory system allows us to breathe in air through the nasal cavity, which is then warmed, humidified, and filtered by nasal concha.
• 👃 The olfactory bulb in the nasal cavity helps detect smells by interacting with particles in the air and sending signals to the brain.
• 😷 Sinuses, which are mucus-lined cavities, produce mucus to trap pathogens and lubricate the nasal cavity.
• 👅 The oral cavity is primarily occupied by the tongue, which contains taste buds for detecting five main tastes: sweet, salty, sour, bitter, and umami.
• 👂 The Eustachian tube connects the nasal cavity to the inner ear, helping equalize air pressure during changes in altitude, such as flying or driving in mountains.
• 👄 The uvula in the back of the throat prevents food from entering the nasal cavity, though it isn’t perfect, as food can still escape into the nose when laughing.
• 🫁 The trachea is kept open by cartilage rings to ensure airflow, while the epiglottis prevents food from entering the trachea during swallowing.
• 🎤 The larynx, or voice box, contains vocal cords that produce sound when air passes through them. The thyroid cartilage, also known as the Adam's apple, protects the larynx.
• 🍃 Bronchi branch into smaller bronchioles, which end in alveoli. These alveoli are where gas exchange (oxygen and carbon dioxide) takes place with the bloodstream.
• 🫀 The diaphragm contracts to expand the pleural cavity, causing air to rush into the lungs. It plays a key role in breathing, with the ribcage protecting the lungs and other thoracic organs.

Q & A

What is the function of the nasal concha in the respiratory system?

The nasal concha slows the air down as it enters the nasal cavity, helping to warm and humidify it. This also aids in trapping pathogens and improving the sense of smell.

How does the olfactory bulb help us detect smells?

The olfactory bulb contains sensory neurons that detect smell molecules in the air. These molecules interact with receptors in the nasal cavity, sending signals to the brain to identify the smells.

What is the role of sinuses in the respiratory system?

Sinuses are mucus-lined cavities that produce mucus, which helps trap pathogens, lubricates the nasal cavity, and drains into the nasal cavity to maintain moisture.

What is the purpose of the eustachian tube?

The eustachian tube connects the nasal cavity to the inner ear and helps equalize pressure between the inner ear and the outside atmosphere, especially during changes in elevation.

How does the uvula prevent food from entering the nasal cavity?

The uvula is a flap of tissue that prevents food and liquids from entering the nasal cavity when swallowing. However, it is not foolproof, which is why food can sometimes come out through the nose when laughing.

What is the function of the epiglottis in the respiratory system?

The epiglottis is a flap of tissue that covers the trachea during swallowing, preventing food and liquids from entering the lungs, which would cause choking or coughing.

What is the role of the larynx and how does it produce sound?

The larynx, or voice box, contains the vocal cords. Air pushed through the vocal cords causes them to vibrate, producing sound. The pitch of the voice is determined by the length and tension of the vocal cords.

Why is the trachea held open by cartilage rings?

The trachea is held open by cartilage rings to ensure it remains open at all times for air to flow in and out of the lungs. Without the rings, the trachea could collapse, blocking airflow.

What is the function of alveoli in the lungs?

Alveoli are small sac-like structures at the end of bronchioles where gas exchange occurs. Oxygen from the air passes into the bloodstream, and carbon dioxide is expelled from the blood to be exhaled.

How does the diaphragm help in breathing?

The diaphragm contracts downward to expand the pleural cavity, creating a pressure difference that causes air to rush into the lungs, enabling breathing.

Outlines

00:00

🫁 Introduction to the Respiratory System and Nasal Cavity

In the first part of the video, we start by practicing how to use the respiratory system before moving on to understanding its workings. The focus then shifts to the nasal cavity, explaining how air enters through the nostrils and is slowed down by three shell-like ridges called nasal conchae. These structures help warm and humidify the air, enhance our sense of smell, and trap pathogens. The olfactory bulb plays a key role in detecting smells by capturing air particles that interact with receptors. The discussion covers how nasal sinuses produce mucus and trap pathogens, protecting the respiratory system.

05:00

👄 Oral Cavity, Eustachian Tube, and Pharynx

This section introduces the oral cavity, where the tongue fills most of the space and is responsible for our sense of taste. It explains the Eustachian tube's role in balancing air pressure between the inner ear and the atmosphere, which is why our ears pop during altitude changes. Additionally, the pharynx, or the back of the throat, is discussed along with the uvula, a flap that prevents food from entering the nasal cavity, though it’s not foolproof, as demonstrated when food or drinks can sometimes come out of the nose.

10:02

🧠 Epiglottis, Larynx, and Vocal Cords

This part covers the distinction between the esophagus, where food travels, and the trachea, where air flows. The epiglottis ensures that food doesn’t enter the trachea when swallowing, while the larynx, or voice box, produces sound. The vocal cords vibrate as air passes through, with pitch depending on the size and tension of the cords. Laryngitis, an inflammation of the vocal cords, affects speech. The section also discusses the thyroid cartilage (Adam's apple), which protects the larynx, and the importance of cartilage rings in keeping the trachea open for constant airflow.

🌬️ The Bronchi, Bronchioles, and Alveoli

Here, the video explains how the trachea branches into two bronchi, each entering a lung and further dividing into bronchioles. These bronchioles end in alveoli, small sacs where gas exchange occurs—oxygen enters the bloodstream, and carbon dioxide exits to be expelled from the body. This segment emphasizes the critical role of alveoli in facilitating the respiratory system's primary function of oxygenating the blood and removing carbon dioxide.

🫀 Lung Structure, Pleural Membrane, and Diaphragm

The lungs are discussed next, highlighting that the left lung has two lobes while the right lung has three. Each lung is surrounded by a pleural membrane, and the pressure inside the pleural cavity is slightly lower than in the lungs, which keeps them inflated. The diaphragm plays a crucial role in breathing by contracting to expand the pleural cavity, allowing air to rush into the lungs. The ribcage protects both the lungs and heart, ensuring that these vital organs are shielded from damage.

📝 Recap and Summary of Respiratory System Functions

This section recaps the key points about the respiratory system, from the nasal and oral cavities to the lungs. It highlights the importance of the nasal conchae in filtering and humidifying air, the olfactory bulb in detecting smells, the roles of the uvula and epiglottis in preventing food from entering the wrong passages, and the crucial function of the alveoli in gas exchange. The video concludes with a reminder of the diaphragm’s role in breathing and the ribcage's function in protecting the thoracic organs.

Keywords

💡Nasal cavity

The nasal cavity is the open area between the nostrils and the back of the throat. In the video, it is discussed as the primary pathway for breathing, where air is warmed, humidified, and filtered before entering the respiratory system. The nasal cavity also plays a role in our sense of smell, aided by the olfactory bulb.

💡Nasal concha

The nasal concha are three ridges inside the nasal cavity that slow down airflow, allowing the air to be warmed and humidified. These structures also help trap pathogens and assist with smell by keeping air in the nose longer. This is important for protecting the respiratory system from harmful particles.

💡Olfactory bulb

The olfactory bulb is responsible for detecting smells. It contains sensory neurons that pick up odor molecules from the air, sending signals to the brain for processing. In the video, this is humorously compared to an 'old factory' as a way to remember the function related to smell.

💡Sinuses

Sinuses are mucus-lined cavities in the skull that produce mucus, helping to keep the nasal cavity lubricated and trap pathogens. The video mentions the frontal and sphenoid sinuses and their role in preventing infections and supporting nasal function.

💡Pharynx

The pharynx, or the back of the throat, is a shared passageway for both food and air. The video highlights its dual function as part of the digestive and respiratory systems, showing its importance in directing food toward the esophagus and air toward the trachea.

💡Epiglottis

The epiglottis is a flap of tissue located above the voice box that prevents food and liquid from entering the trachea when swallowing. In the video, it is emphasized as a key structure in ensuring that food goes into the esophagus instead of the lungs, preventing choking.

💡Trachea

The trachea, or windpipe, is a tube that transports air from the throat to the lungs. It remains open due to cartilage rings that prevent it from collapsing, ensuring continuous airflow. The video explains how the trachea branches into the bronchi, which then lead to the lungs.

💡Alveoli

Alveoli are small, sac-like structures at the end of bronchioles in the lungs where gas exchange occurs. Oxygen from inhaled air is transferred to the bloodstream, and carbon dioxide is removed from the blood and exhaled. The video points out their critical role in oxygenating the body and expelling waste gases.

💡Diaphragm

The diaphragm is a large muscle located below the lungs that contracts and expands to facilitate breathing. The video describes how it works to increase the size of the pleural cavity, causing air to flow into the lungs. It plays a key role in breathing mechanics, though we don't consciously control the lungs directly.

💡Pleural membrane

The pleural membrane surrounds the lungs and lines the pleural cavity. It helps maintain negative pressure in the pleural cavity, keeping the lungs inflated. In the video, this is likened to how pressure inside a balloon must be higher than the outside to prevent deflation, similarly to how the lungs are kept inflated by the pleural membrane.

Highlights

Introduction to the respiratory system with a focus on how we use it by breathing in and out.

Explanation of the nasal cavity's structure and function, including the role of the nasal concha in slowing down air for better humidification and pathogen trapping.

Detailed discussion of the olfactory bulb and how sensory neurons help us detect smells by interacting with particles in the air.

Description of the sinus cavities and their role in mucus production, which helps lubricate the nasal cavity and trap pathogens.

Explanation of the oral cavity, highlighting the size and function of the tongue, and the role of taste buds in detecting five distinct tastes.

Overview of the eustachian tube, which connects the nasal cavity to the inner ear and helps equalize pressure during changes in elevation.

Introduction to the pharynx, the back of the throat, and the uvula, which helps prevent food from entering the nasal cavity.

Description of the epiglottis, a flap of tissue that prevents food from entering the trachea when swallowing.

Explanation of the trachea's structure and function, including its division into two bronchi that lead to the lungs.

Introduction to the alveoli, small sacs at the end of the bronchioles where gas exchange between air and blood occurs.

Description of the differences between the right and left lungs, with the right lung having three lobes and the left lung having two lobes.

Explanation of the pleural membrane and the importance of keeping a lower pressure in the pleural cavity to prevent lung collapse.

Overview of the diaphragm's role in breathing by contracting to expand the pleural cavity, allowing air to flow into the lungs.

Introduction to the rib cage's role in protecting the lungs and other thoracic organs.

Recap of the entire respiratory system, including a step-by-step review of the structures and their functions in the breathing process.

Transcripts

first part of the video we're going to

practice using the respiratory system

then we'll learn how it all works so

take a deep breath in

and then breathe out now that we've

mastered using the respiratory system

we're going to learn how it works

let's jump to the white board we're

going to start with the nasal cavity now

you're probably already familiar with

the nasal cavity it's the

open area between your nostril and the

back of your throat but you probably

haven't explored too far

back there before i was a picking your

nose joke now you'll notice in the nasal

cavity that there are these three ridges

called the nasal

concha it's the same root as conch like

a conch shell

and so these are three shell-like ridges

in the nose

and the purpose of these is to slow the

air down which will warm it

help it stay humidified we also smell in

the nose so by keeping the air is kind

of swirling around in there a little bit

longer it helps with our sense of smell

and it can help trap pathogens in there

think about if the air just went

straight back down the throat right away

then it would be easier for pathogens to

make it through but if the air swirls a

little bit those pathogens can get

caught in our mucus and our nose hairs

and things like that so the nasal concha

are there to slow the air that we

breathe in

to help trap pathogens help us smell

better and warm and humidify the air

that we breathe now at the top of this

in yellow drawn here is the olfactory

bulb olfactory just means smell i think

about like

you're driving down the highway and you

smell oh that's the fact there's like an

old factory nearby

and it smells really bad like they're

making dog food or something and it's a

smelly old factory olfactory sense

the olfactory bulb has sensory neurons

that hang down in here

and whenever we smell something it's

actually the molecules

of that thing that are in the air are

going to interact with those little

receptors

that hang down from our olfactory bulb

and sends

signals then to our brain so this

olfactory nerve right here

connects back to our brain so that we

can detect what we're smelling

so next time you smell something that

doesn't smell very good remember there's

actual particles of that thing

making it into your nose all right let's

move on

drawn here now are a couple of our nasal

sinuses

our sinuses are these mucus-lined

cavities whose job is to make

mucus and of course when they get

infected then we have a sinus infection

we've got kind of four sets of those

i've got two drawn here

the frontal and the sphenoid the frontal

sinus is right in here

the sphenoid sinus is kind of back

behind the nose we also have the

maxillary sinuses which are in our

cheekbones

and the ethmoid sinuses which are

between our eyes but just know for now

that the sinus cavities are mucus-lined

cavities

that drain down into the nasal cavity

which is where we produce our mucus or

snot

mucus of course is really important

helps lubricate your nasal cavity and

also helps keep pathogens in it traps

those pathogens

and if stuff gets in there that

shouldn't be there that's why we have

runny nose to try to get rid of those

pathogens that have made it into

our nasal cavity up next we have the

oral cavity

the oral cavity of course is our mouth

now

in my diagram here it looks like we have

a big open oral cavity but most of that

oral cavity is actually taken up

by our tongue think of your tongue as

this like little bitty piece that kind

of like sticks out of your mouth

but your tongue is giant and it fills up

most of your mouth the tongue of course

has taste buds which are connected to

sensory neurons which sends signals up

to the brain for

tasting our five things that we can

taste sweet salty bitter

sour and umami anything else that we

taste like flavors that's really our

sense of smell

if it's not one of those five we didn't

taste it we smelled it up next we have

this little

opening it's the opening to a tube

called the eustachian tube and it's

found

sort of in the back of our nasal cavity

right there and that's going to connect

our nasal cavity

to our inner ear think of a time where

you've been changing elevation like

going on a flight in a plane or driving

up into the mountains

and your ears start to pop well that's

because the inside of your ear not the

part that you can get to like this

but the part that's on the inside of

your eardrum if that inner ear part has

a different

pressure than the air pressure on the

outside of your ear then it

it starts to feel weird it can hurt and

then whenever your ears pop

or equalize the pressure that's because

air can float in or out of the

eustachian tube

and that's why it helps to like chew gum

or to swallow or to yawn

those things will help open up the

eustachian tube so air can pass in or

out

to equalize the pressure between the

atmosphere around us

and our inner ear now the back of the

throat we have a special name for which

we call

the pharynx the pharynx it's not a

special structure

it's just a name for the back of the

throat so pharynx is the back of the

throat

and we have this thing called the uvula

now if you've ever seen a cartoon where

the character opens their mouth and in

the very back of the throat there's like

this dangly red thing right there

i always used to think that was the

tonsils but it's not the tonsils

it's the uvula the purpose of the uvula

which is this flap of skin that hangs

down in the back of the throat

is to prevent food and other things that

we eat or drink

from making it into our nasal cavity now

it's not perfect if you've ever had milk

come out your nose because you were

laughing while you were drinking milk

then that's because your oral cavity and

your nasal cavity are connected

and your uvula is not perfect and

whenever you were laughing some of that

food made it from

the back of the throat here and the oral

cavity up into

the nasal cavity and that's never a

pleasant feeling so the uvula prevents

food from making it into your nasal

cavity up next we have two tubes that

the throat divides into

one is going to be the esophagus and

that's where you want food to go

the other tube is the trachea and the

trachea we want to stay

open because we breathe in and out and

that air goes into the trachea and we

we're never not breathing right

generally so it's helpful if we keep the

trachea just

open all the time the one time when we

don't want the trachea open

is whenever we're swallowing food or

drink so to help prevent

food or liquid from getting down into

the trachea and therefore down into the

lungs

which is what's happening whenever you

take a drink of something and it goes

down the wrong way and you start

coughing

that's you getting that liquid or that

food out of your

lungs well we've got a special structure

to prevent this from happening and

that's called

the epiglottis the glottis is sort of a

term for the top of the voice box right

here so epiglottis means above that and

whenever you swallow

this flap of tissue right here gets

pulled on by a tendon right here and

it's going to bend that down to

cover up the space right here so the

moment that you're swallowing food food

all goes down into the esophagus and

none of it goes down

into the trachea which would cause you

to cough so two things that keep the

food where it needs to be we've got the

uvula which prevents food from going up

into the nasal cavity and we have the

epiglottis which prevents food from

going down into the trachea and

therefore into the lungs

now at the superior part or top of the

trachea we have something called the

larynx

the larynx is another name for your

voice box and right here

drawn are the vocal cords whenever you

speak

air is pushed up through the trachea out

of your lungs and it causes the vocal

cords to vibrate the wider or longer

your vocal cords the deeper your voice

will be

and the smaller your vocal cords the

higher it will be and of course you can

change the pitch of your voice because

you can

change the vibration frequency of your

vocal cords but only to an extent so we

all have a limited

vocal range and if you have inflammation

of this area where it swells up and your

vocal cords aren't able to vibrate then

you've got

laryngitis laryngitis is inflammation

that's the itis part

of the larynx laryngitis now we need to

protect our larynx so we have a special

piece of cartilage called the thyroid

cartilage

that sits in front of our larynx this is

also known as that adam's apple

and men and women both have it it tends

to be more pronounced in men so people

think

that just men have an atom's apple but

really men and women both have it it has

nothing to do with the thyroid gland and

the endocrine system as far as what it

does or what it is

the only similarity there is where it's

located which is why they share the name

so thyroid cartilage protects the larynx

next we have the rest of the trachea

you'll notice the trachea is covered in

these cartilage rings i use light blue

in the diagram here for cartilage

they're covered in these cartilage rings

and the purpose of that is to hold

open the trachea like i said we're

always breathing we want the trachea to

never be obstructed because then we

couldn't get oxygen into our lungs that

would be bad

so these cartilage rings hold open the

trachea so there's always

air flow moving in or out of our lungs

contrast that with the esophagus which

stays closed most of the time if we're

not swallowing food or drinking water

and at the bottom

of the trachea it splits into two what

we call bronchi or bronchus for singular

but two of them so there's two bronchi

the bronchi enter each lung and from

there they're going to branch out into

smaller divisions called bronchioles so

trachea there's just one

they're split into two bronchi and each

bronchus

splits into many bronchioles that

changing of the ending to

oles that just means they're smaller

like arterioles or small arteries or

venules are small veins now in the lung

at the end of

each bronchiole is a little sort of

cloud-shaped sac

called alveoli contrary to popular

belief alveoli are not my favorite type

of pasta that would be penne just

kidding all pasta is

delicious but the alveoli are where the

air ends up going so that it can

transfer

oxygen and carbon dioxide back and forth

between

the air that we breathe and the blood

vessels that enter our lungs

so each of these little alveoli that are

at the end of the bronchioles

those are wrapped in little capillaries

little tiny blood vessels that connect

to our bloodstream

so they can exchange the oxygen and the

air that we breathe

into the bloodstream and then take out

the carbon dioxide that we don't need

anymore

out of the bloodstream so that we can

breathe it out so the alveoli is where

gas

exchange occurs that's super important

that's the whole point of all this right

to get oxygen into our bloodstream

that happens in the alveoli and of

course we have two lungs now while the

second lung is being drawn

notice something that this left lung

this is the left side by the way it's

the right side from your perspective but

if this person's facing you it's their

left so the left lung has two lobes so

lower lobe

upper lobe our right lung however has

three lobes so we've got a lower

a middle and an upper lobe so right lung

three lobes

left lung two lobes now around each lung

is a pleural membrane the lungs are in

the pleural cavities and the pleural

cavities are surrounded by this membrane

it's really important actually the

pressure in the lungs right here like in

the bronchi and the bronchioles

is actually a little bit higher than the

pressure in the pleural cavity

that's surrounded by the pleural

membrane think about it like a balloon

your lungs are like a balloon

if the balloon has the same pressure as

the air around it it's actually

deflated we don't want our lungs to

deflate we call that a collapsed lung it

can happen whenever

the lung itself gets damaged or if the

pleural membrane gets punctured

so we have to keep this space right in

there between the lung

and the pleural membrane we actually

have to keep that at a negative relative

pressure it's got to be at a lower

pressure

than the lung itself so the lung stays

inflated like a balloon the pressure in

the balloon has to be higher than the

pressure around it

for it to stay inflated so just remember

in the pleural cavities

the pressure is a little bit lower than

in the lungs below the lungs we have

the diaphragm you may have had a music

teacher say you know to sing from your

diaphragm but you also have to breathe

from your diaphragm

your lungs actually you don't breathe

with your lungs you don't send signals

to your lungs to breathe

you send signals to your diaphragm what

the diaphragm does is it contracts

downward which expands the size of your

pleural cavity that's going to cause

air to rush into the lungs because of

that pressure difference

sort of like sucking liquid through a

straw so you can track the diaphragm

down

that's going to cause air to rush into

the lungs and your lungs then expand

but again you're not controlling the

lungs directly you're controlling the

diaphragm so the diaphragm

helps you breathe by expanding the

pleural cavity

finally of course all of the thoracic

cavity is surrounded and protected by

our rib cage and the purpose of those is

to protect

our lungs and our heart and our other

thoracic organs from being damaged

all right let's do a quick recap we have

the nasal cavity which is where we

breathe air

into our nose we have the nasal concha

which are there to

swirl the air and warm it humidify it

trap pathogens

as well as keep the air there a little

bit longer so we can smell it better we

have the oral cavity which is our mouth

and most of that's filled with our

tongue

we have the olfactory bulb which is for

detecting smell molecules will connect

to those receptors

and that'll cause signals to be sent

back to our brain so we can process

those

things that we smell we have the sinus

cavities which are lined with mucosa or

membranes that produce mucus to help

lubricate our nose and help flush out

pathogens and things like that we have

the eustachian tube which connects to

our inner ear and that's going to help

equalize the pressure between our inner

ear

and the air around us we have the uvula

which is going to prevent food from

making it from our oral cavity

up to our nasal cavity which is not good

the pharynx is a name for the back of

the throat

the epiglottis is a flap of tissue that

whenever we swallow it's going to close

off the trachea to prevent food and

water from making it down into our lungs

we have the esophagus right there

and then the trachea at the top of the

trachea is the larynx

which is going to be where our vocal

cords are the thyroid cartilage protects

the larynx

that's the adam's apple the trachea is

held open by these cartilage rings

and then the trachea branches into two

bronchi each bronchus branches into

bronchioles and then finally down into

alveoli

alveoli is where gas exchange occurs

oxygen will go from the alveoli into the

blood and carbon dioxide will go from

the blood

into the alveoli so we can breathe it

out the lungs of course are surrounded

by the pleural membrane

and the space inside the pleural

membrane is kept at a lower pressure

so their lungs stay inflated we've got

the diaphragm which we contract in order

to breathe

and the ribcage of course protects all

of the thoracic organs that we've been

talking about all right here's a blank

diagram take a moment see if you can

identify all of the structures in this

diagram

as well as what they do here we have the

nasal cavity which we bring air into

we've got the nasal concha which are

going to swirl the air we've got the

oral cavity which is our mouth

we've got the olfactory bulb which is

for sensing smell we have the sinus

cavities

we have the eustachian tube which

connects to our inner ear we have the

uvulo which prevents food from getting

into the nasal cavity

we've got the pharynx which is the back

of the throat we have the epiglottis

which prevents food from making it down

into the trachea

we've got the larynx which is where our

vocal cords are we've got the thyroid

cartilage which protects our larynx our

vocal box we have the esophagus which is

where food and

drink go down we have the trachea which

is where air goes down into that trachea

branches into the two bronchi which

branch into bronchioles

which end in alveoli where gas exchange

occurs with the bloodstream

we have the lungs which are covered in

the pleural membrane

the left lung has two lobes the right

lung has three lobes the diaphragm which

will contract to help us breathe and

finally the rib cage which protects all

of this

take a moment and breathe okay we're

gonna use our respiratory system breathe

in

breathe out

you think that's funny

good job wait where'd the laundry go

where did laundry go

there she is right bye bye