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Chapter 21 Lecture

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now this is actually one of the more simple

simple

uh body systems and anatomically there's

not a whole lot to this actually there's

only a few parts you can see it all

right here on the diagram

uh the organs that are included in the

respiratory tract and lungs

uh the nasal cavity nose pharynx larynx

the lungs trachea bronchi those are the

things that are going to be included in

this particular

body system it also includes the

includes the blood vessels the pulmonary

circuit the rib cage

and the muscles that allow your rib case

to expand and contract

mostly what you have in your respiratory

system are hollow pathogens

passages what they do is to exchange gases

gases

so each component of the tract has

unique growth and histological

uh structure and includes all those

now we can divide the respiratory system

up into what we call the lower

respiratory tract and the upper

respiratory tract

the upper respiratory tract are just the

passageways the air takes to go from

your nasal cavity to your larynx

the lower respiratory tract is going to

be where it actually exchanges gases

with your blood

so we're talking about your alveoli and

your lungs the vli

are little grape like clusters where

their gases are exchanged

with the blood carbon dioxide oxygen are

going to be exchanged

at this point the lungs are the places

that house them

they're spongy organs in the thoracic

cavity they're enclosed in the

boundaries of the ribcage and your diaphragm

diaphragm

and each one of those is a collection of

millions of alveoli

how many millions 150 million of you

allow that's the number actually i mean

there actually are inside there

and what they do is to expand whenever

air comes in and what's going to happen

at the alveolus is you're going to give

oxygen to your blood and take carbon

so we classify the respiratory system

based on some some zones we classify

them based on what they do

functionally into conducting and

respiratory zones the twos of the

conducting zones are just places where

the air travels whenever you inhale it

or we call that inspiring

or you exhale it or expiring majority

of the surface area of the respiratory

system is just that conducting zone

so as it comes to the conducting zone

it's filtered it's warmed and it's moistened

moistened

and this includes all the structures

from your nose all the way down the

bronchial so the

majority of this is in fact conducting zone

zone

the respiratory zone where gas exchange

occurs only little bitty structures that

are in the alveoli

so the respiratory zone is by the

surface area

very small compared to your conducting zone

now what respiration is is actually

a combination of four separate processes

this is the function

of the respiratory system and now why is

that so important because what it does

is to give our body oxygen and take away

wasteful carbon dioxide

so there are several different ways this

can occur and this all works together

pulmonary ventilation is the movement of air

air

into and out of the lungs that's the

that's that

pulmonary gastric exchange this is what

occurs in the lungs and the blood

so the gas carbon dioxide and oxygen are

be exchanged

in the lungs that carbon dioxide and

oxygen is also

transported through your blood we call

that gas transport and it makes its way to

your tissues tissue gas exchange is the

movement of gases

now what else does your respiratory

system do

well it also has some other functions

you have the mechanism for speech and

sound production that's how i'm talking

to you right now

what's happening is whenever you are speaking

speaking

air is being pushed across your larynx

and that's going to vibrate

your vocal cords and then that makes

this noise that you hear

that's that all right so that's how we

are able to produce sounds

you also have neurons in your

respiratory system that are responsible

for a sense of smell

we talked about that at the beginning of

the semester

and it is possible and we know this

to expel contents from the abdominal

pelvic cavity to assist with defecation

urination childbirth by increasing

pressure and thoracic cavity

you guys know about that whenever you go

to pee or poop and you go

that straining that's got a name for

it's actually called the valsivars

maneuver and that's the pushing that you

do whenever you're

defecating or even when you're having a child

child

that pushing that's called the valsivars maneuver

maneuver

so that's your thoracic cavity changes

are helping you to do that

pressure changes in the thoracic cavity

also assists with venous blood flow and

lymph transport

so you guys remember the respiratory

pump we talked about that in the in the

lymphatic chapter that's going to be

working whenever you're breathing in and

out your respiratory system also

helps you to maintain acid base balance

very very important it can be disturbed

by changes in your breathing and also

we do synthesize an enzyme involved in

the production of angiotensin

which is going to help control blood

pressure and fluid homeostasis so the

respiratory system

very very important for your life

without it you would die

and we're going to talk about how it

actually works

now the nose and nasal cavity

are the entrance way into your

respiratory system and they

have some functions that are really

important for you one thing they do

is to warm the air if the air is too

cold to hit your lungs that can

cause some very unpleasant feelings we

had that before happen

it's also humidified you don't want your

lungs to dry

out from dry air so you have to humidify

that air as it goes in

debris is also filtered antibacterial

substances are secreted so

the debris is filtered from from the air

into your lungs that way you don't catch

something that may have brought in now

around here

that's actually really important because

we have a lot of peanut dust because of

the forming around here

you also have the olfactory receptors

housed here in the nasal cavity

and this is also enhancing the resonance

of your voice so the

fact that it's got some space in there

is allowing you to throw

that's what it looks like this is a model

model

i have one of these in the lab if you

want to check it out you're more than

welcome to do that

this is the model of the nasal cavity

so the air is going to enter the nasal

cavity which is a hollow space

frame by the bone and hyaline cartilage extends

extends

uh actually between two posterior nerves

so the nares are basically your nostrils

that's what we're talking about here so

the nasal cavity is actually divided into

into

left and right portions by the nasal septum

septum

now your first discussion question

i would like you to tell me why do you

think you've got

two places where air can enter you got

two nostrils

got two sides why do you think you have

two sides

why not just have one big hole to get

more air in why is there a partition there

there

what purpose do you think that serves to

have a partition in the middle of your nose

nose

so tell me why you think that's

important for you that's your first

discussion question

now the vestibule this is the most

anterior region of the nasal cavity just

inside the nostril you got

hairs here to prevent large objects from

entering your nasal cavity

you don't want big old things coming

inside there because it could it could

really damage the inside of your nose so

the hairs are there to protect you

they do fill up with you know mucus and

things like that

and and dust and whatever and it becomes

kind of gross but that's

there on purpose to stop that stuff from

getting inside your body

now the bony projections that you have

in the nasal cavity the superior

inferior and middle conkey

these are processes of the ethmoid bone

i talked about that back in amp1

the inferior concrete fill most of the

space in the nasal cavity now what these do

what they're doing here is to increase

surface area

so they're allowing passageways to

funnel the air

to the right spot that way it can be

humidified and

warmed and and it won't be so cold

all right so the conchi curl around for

your passageways we call these meatuses

so superior middle and inferior nasal meatuses

meatuses

this create turbulence that rids the

dust and debris from inspired air

so basically what happens here is that

the junk you breathe in

falls out right there because you don't

want it to go down any farther

now in addition to having these concrete

you also have sinuses

that's exactly what i'm talking about

that kind of sinus stuff that's

what that's caused by perinasal sinuses

are hollow cavities within several the

bones that you have in your skull

and they're connected to the nasal past

nasal cavity by small passageways and

what they do

is to help warm the air and enhance

voice resonance and reduce the weight of

the skull

however because they are lined with

mucous membranes

bacteria can become trapped there and

infect them

we get that fairly often here in blakely

because we have

like sinus infections because we have so

many things that are in the air around here

here

so sinus infections occur quite often in

our population

because of the fact we have so much

stuff in the air

now that should explain to you the

reason why

your voice sounds funky whenever you

have a sinus infection

because the sinuses if they're clogged

they don't work properly

and then the the function of the sinuses

is to give you a voice resonance so if

it doesn't work then

the nasal cavity the vestibulus line

with stratified chromos epithelial tissue

tissue

that resists mechanical stress because

stuff's hitting it all the time you're

breathing in air every second right

you also if you have to scratch your

nose that's why you have that there

behind the vestibule it changes to a

different type of

epithelial tissue olfactory mucosa and

respiratory mucosa

the olfactory mucosa is located on the

roof of the nasal cavity and this is

where you've got

receptors for this for the sense of smell

smell

it's actually kind of funny this is the

only place in your body where neurons

actually touch the outside

so the neurons are just hanging out

there waiting for stuff to fall on them

to stimulate your sense of smell this is

the only place in your body where a

neuron actually meets the outside of

your body and this is inside the

olfactory mucosa

the rest of the nasal cavity is lined with

with

pseudostratified cylindic chlorine

epithelium sorry about bringing

bad memories from ap1 i'm sure you

remember that it was the slide with the

tall cells

that looked that they were on top of

each other but they actually weren't um

and goblet cells which are inside that

what these do

is to trap particles in mucus

so the cilia help trap particles the

mucous substrate particles and it

prevents it

from going down any further in your

nasal cavity

so we don't want this to go any we don't

want to go down our lungs

back up so this propels the mucus

towards the back nasal cavity and the pharynx

pharynx

so that we can swallow it why would you

want to do that well

you swallow that junk because

your stomach acid is very very acidic

and it will destroy most of the things

that you put in there

so you don't want your you don't want

your nasal cavity to be

filled with that stuff because you can't

breathe and does ever happen of course

listen you hear that it's happening

right now so this is the

mechanism that your body uses to try to

get rid of stuff

that could potentially become irritated

now the pharynx is the next anatomical

segment of the respiratory tract that

inspired air

enters after exiting the nasal cavity

this is on the diagram here's the first

part that starts in blue

and you've actually got three parts to

this and they're listed right here on

the picture

nasopharynx oropharynx and

laryngopharynx this

nasopharynx that means it comes from the

nose this is the part

that is going to filter air towards the

back of your throat

the oropharynx is the part that's going

to filter water or food to the back of

your throat

lorenzo pharynx is going to go towards

your larynx

now what the nasopharynx does it's lined

with pseudostratified syllable

epithelium tissue to humidify

and filter inspired air so really

the best thing for you to be doing is to

be breathing through your nose if you

can because you don't get that same

protection if you breathe through your mouth

mouth

because you don't have that same cilia

and stuff doing it now stuff you still

have some protection you got tonsils

that are going to help filter but you

don't have the protection that your

nasal cavity offers

now the nasopharynx extends from the

posterior narrows the back part of the nostrils

nostrils

to the uvula the uvula

is that little soft thing that hangs

down what that does

it moves when you swallow and it covers

your nasal cavity so when you swallow

food should only go one direction and

that should be down

it should not come the other direction

now does it ever happen

sure think about back when you were a

child and you were something was funny

and you spilled milk out your nose yes

it happens

because you're trying to breathe and

talk and chew this all at the same time

right so

stuff happens but majority of time when

we swallow that's covered

so that we don't spill that food or

water whatever it is out our nasal cavity

cavity

water does not belong there the cells

that you have there

they don't like being wet from water

that's why it burns when you get

water up your nose this should not be

now oropharynx this is the next segment

this extends from the tip of the uvula

to the epiglottis and larynx

this is filled with non-keratinized

stratified squamous epithelium

which is more protective than your nasal

cavity that's why if you get

through your nasal cavity it's

irritating if you get food right here

it's no big deal this is what it's made for

for

this is a passageway for both air and food

food

lorenzo pharynx this is the last segment

and this extends from the highway bone

to the esophagus and the anterior larynx

opens to the

longer pharynx opens to the larynx or

the voice box the posterior opens into

the esophagus

now it is at this point here that you see

see

that it is entirely possible that we

start choking

in our design the way humans are

designed these two things are

really close together and

sometimes that is a problem

because sometimes we're trying to do something

something

at the same time we're trying to eat

like talk right so what happens

is that the the epiglottis which should

be covering up your

your larynx and your trachea during eating

eating

is uncovered and food goes down the

larynx and it should not be and so

because the cells of your larynx are

specialized to take in

air when something else touches them

other than air

it triggers a violent reflex to try to

get that

out that's coughing right when it

happens in your in your

nasal cavity it's sneezing it coughing

and sneezing actually initiated by the

same thing

and what should be happening anytime you

swallow is that the

the epiglottis should be covering up

the layering so the food passage down

the esophagus

now the esophagus has got the

specialized epithelium

that way it won't be damaged by food

that's being pressed down against it

we'll talk more about that in the next chapter

chapter

actually but for now i just want you to

know that

lorenzo pharynx is that last segment

that it goes from

and the larynx or voice box this is what

what's going to house your vocal cords

you've got a couple different types of these

what they do these are these are types

of cartilage

that are going to be in and

special elastic cartilage special types

of cartilage are going to be

vibrated to be able to produce sound

that's what's happening right now

uh you've got stratified squamous

non-keratinized epithelium

protects your your larynx from

mechanical stress to vocal cords where

food and air both pass through

and you've also got pseudostratified

facilitator epithelium which is found

behind or below the vocal cords which is

to propel mucus and debris up out of the

larynx as one goes

your people do that all the time and

that's what they're doing they're

clearing their throat that's that

that's that noise

this is what it looks like again cartilages

cartilages

sections of cartilage three paired three

unpaired and six paired

provide a framework it's got to be flexible

flexible

it's flexible because if you had no flex

flexibility there then everything would

sound just like this

you would never be able to and that

would be boring right some of you

probably think i sound like that anyway

but i really don't i promise

um the cricoid thyroid and ironic

cartilages are made out of hyaline

cartilage where the roast

rest of them are made out of elastic

cartilage your vocal cords actually are

made out of elastic cartilage and what

that's doing is

is changing shape to be able to produce

different types of sounds

so if you look at it from the front side

the thyroid cartilage there's a little tip

tip

i'm going to try to circle that with the

pointers you'll see it should be circled

on there a little tip come on

there we go uh it's in red i circled it

in red on the other that's called the

laryngeal prominence

that's the tip of the thyroid cartilage

that's your adam's apple

so that's a circle there for you on the

diagram the adam's apple is

the place that we have this thyroid cartilage

cartilage

it's named thyroid cartilage because

it's near thyroid gland

the trachea also known as the windpipe

it's actually a really interesting

structure the trachea has got a lot of

cartilage in it and it goes down

past your larynx all the way down to

your lungs it's going to divide there

and take air now the trachea

has got a lot of space you see that at

the bottom here it says lumen

of trachea that's the space what the

lumen does is to provide a passageway

for air

now look see how it's nice and open and round

round

look behind and you see the esophagus

esophagus is kind of smooshy

well the reason for that is because

you do not have to be eating every second

second

you do not need to have food in your

stomach all the time so the esophagus

can push take its time pushing through

there it's not going to kill you if you

can't eat

but it is going to kill you if you don't

get oxygen to your lungs

so the trachea must be

open at all times it has to be so

what you've got around it that you don't

have around the esophagus

are these cartilaginous rings they look

kind of like c's it's kind of a c-shaped ring

ring

they're supportive but they're also flexible

flexible

so you can change the amount of air

going into your lungs by changing

the flexibility of these rings so it

allows you to

it allows you to get bigger or smaller

when a person is choked or strangled

really this person is strangled

this is closed up because they can't

they can't uh

breathe because that's closed and it's

no fun

all right uh it's certainly unpleasant um

but that's what's causing a person to

pass out because they don't have any

air coming in the trachea now it it

it has a elastic connective tissue and

smooth muscle which allows it

allows the esophagus to span during

swallowing so

it's not completely covered with

cartilage because you got that smooth

muscle there right next to esophagus to

allow the esophagus to get a little bigger

bigger

so that's usually why actually it is why

you don't

breathe at the same time you take a

swallow of food because

you can't really and when you do joke because

because

you're not supposed to be doing that

because it's actually two things you

should not make occurring at the same time

now the trachea the last brachial

cartilage is called the carina this is

also forms a little hook that curves

down and back to the partial rings that

surround the first branch of the

bronchial tree

it's called bronchial tree because it's

got branches again if

you get something in there that is not

supposed to be in there

like something really solid really large

inside like water

or food items it's going to try to get

that out

by violent cough reflex it's going to

contract to try to get that out

so that's why you cough

the mucosa the trachea is again lined

with pseudostratified

epithelial tissue now what they do it's

actually kind of cool

what happens you see in this picture

here at the bottom left you see these

this tracheal tissue you see the the

cartilage and you recognize that from mp1

mp1

and you see the pseudostratified

epithelial tissue you recognize that

from mp12 i'm sure

but you also see the the the

linear at the top the linear projections

those are the cilia

the cilia are going to be pushing

the uh whatever's in them back up

towards the top of your throat you'll

swallow it

that includes bacteria viruses fungal

spores whatever it catches

it's going to push that up to the top of

your larynx so you'll swallow that

instead of

breathing it down to your lungs this is

a filtering function

and what that does is to get that stuff

in there so you'll swallow it and

not breathe it in because you do not need

need

fungal spores bacteria or viruses in

your lungs

does that ever happen yeah unless

pneumonia comes into play

but we would try not to have that happen

and what will happen is that you will swallow

swallow

that and kill it instead of making you sick

once the air reaches the carina

it can be pummeled to the left or right

primary bronchus again you've got two of

these in case one of them stops working

once inside the lung each bronchus

divides into a bronchial tree and it

gets smaller and smaller and smaller eventually

eventually

now the bronchial tree becomes smaller

the cartilage changes from c-shaped

rings to complete rings

and then finally you just have these

irregular type plates now the primary

bronchi is the first place where it divides

divides

left and right branches of the carina

they didn't divide into smaller

secondary bronchi

and then there's three on the right and

two on the left this is due

because of the position of the heart so

the lungs are not

perfectly symmetrical they actually look

different on the left side they do on

the right side because of the way your

heart's facing

the secondary branchy may branch into

into about 10

smaller tertiary bronchi prolong and

continue to branch into smaller and

smaller smaller branches until finally

the bronchials are the smallest airways

and their features are different from

larger airways

they have simple cuboidal epithelial

tissue with very few cilia

if any they have enclosed within the

thick ring of the smooth muscle

and there's no hyaline cartilage what's

happening here is that air is pushing

down to them

the conducting zone the respiratory

tract ends when inspired air reaches

terminal bronchioles that means the end

terminal bronchioles branch into two or

more two or more smaller respiratory bronchioles

bronchioles

surrounded by smooth muscle the

respiratory zone

begins with respiratory bronchioles with

a vli that are budding from the wall so

they look like a bunch of grapes and

what they're doing

is they're going to be the end result of

the breathing in

from your lungs each respiratory

bronchial has

ducts which have the alveoli attached

to their wall so the sacks the uv li are

like little grapes and the inspired air

has arrived where gas exchange is going

to occur so the

alveoli are these sacs that

that's going to be the respiratory zone

this is the only part of the

of your respiratory system that actually

where gas exchange does in fact take place

so it looks like visually the air comes down

down

for terminal bronchiole it hits the

respiratory bronchial and then you start

to have this

this uh push out of for

the alveoli so the vli are small little

grape like sacs

where the air is going to be pushed through

through

now this is the pathway of air so i'd

like to review this with you so you know

exactly which direction it goes i would

like you to know this for your for your

test i'm going to ask you about it

the airway goes from the nares to the

nasal cavity

to the narrow nasopharynx oropharynx

orange pharynx

from the larynx down to the trachea it's

the primary bronchi the splits in the

secondary tertiary and finally all the

different branches of the bronchi

it goes to the bronchioles smaller

terminal bronchioles even smaller

respiratory bronchioles

to the vehicle redux and finally to the

alveolar sacs which is where it's going

to be

exchanging gases with the blood so

definitely want you to know the order

of this it's very important that you understand

understand

now when you get to the alveoli the vli

are the final destination for inspired air

air

so the air's got several things and it's

got oxygen carbon dioxide

nitrogen majority of its nitrogen and

that doesn't really do anything this

just kind of

comes in and comes out but you do have

several different types of cells that

are going to

take that inspired air one is called a

type 1 alveolar cell

these are squamous cells that account

for about 90 of the cells in the velar wall

wall

they're very thin and they allow for

rapid diffusion of gases so the thin

kind of structure there

is for diffusion you see how close the

blood vessel is to the velous

so you can get through there now they

have a very

humongous amount of surface area which

increases this gas

exchange so this is again an example of

what they look like affects what it does

type 2 alveolar cells these are smaller

cuboidal cells

and they're only about 10 of the cells

in the velar wall this is responsible for

for

surfactant surfactant is kind of an oily

greasy type

chemical that helps reduce surface

tension on alveoli

so you don't want the violets to close

up that's the last thing you want

because it could

that's what happens a person's got copd

that close up you don't want it to

happen so surfactant is there to keep

that from from occurring

you also have and there are little blue

things here

alveolar macrophages they're mobile

phagocytes means they move around

they have to have some surfactant to

meal to move around if you don't have

any surfactant they stay stationary

what they do is to clean up and digest

any debris that may display down there

does that ever happen

of course it does especially if you smoke

smoke

but if you smoke then the tar itself

covers them and they can't move around

so they can't

the lungs the lungs consist of the

alveoli and everything that's around them

them

so the right and left lungs are

separated by the heart and immediate

stein in the middle part of your chest

the lungs inferior flat base rests on

the diaphragm

while it's apex sits just below the

clavicle they're actually

really large organs so the very top of

it is right below your probably right

above your collarbone

the bottom of it actually goes really

far down into your your cavity so far

down that sometimes people think they've got

got

kidney stones or appendicitis really is

your lungs messing with you

so they're actually very large organs

the front back and lateral surfaces are in

contact with the rib cage we call this

the costal surfaces that means cartilage

of the rib cage

um it's in contact with mediastinum we

call this the midi style surface

and of course like all the other all the

other organs we're going to talk about

you've got a hilum a hilum is a

depression found on the media style

surface where each lung where things

like blood vessels

nerves enter the exit the lung you got

these in your kidneys you got these in

your spleen

you got several of these throughout your

your organs

and finally the left lung looks a little

different than the right lung

it's got a cardiac notch what do you

think goes in there

well this is the place where your

heart's going to fit the cardiac notch

because the heart

is facing towards the left and down

that's why you got that there you have

that there to be able to

have the place where the hearts going to

indent into that cardiac notch

each lung is divided into lobes the

right one's got three lobes the lepens

only got two lups

again that's because of the space of the

heart the right lung has got a superior

middle and inferior lobe

and you got fissures that separate each one

one

the left lung is divided into superior and

and

inferior that's it they've only got an

oblique figure so they don't look the same

same

the lungs are found within the pleural cavity

cavity

the pleural cavity is a subdivision of

thoracic cavity

and this is located between your serous

membrane you guys remember from amp-1

serous membranes

are those membranes that cover things

like the

the uh heart and lungs to be able to

keep them from smashing into each other

whenever they move

so the parietal pleura so the outer

layer of serous membranes diffuse

the the rib cage diaphragm and other structures

structures

the highland the parietal plural turns

over itself to create the inner

membrane known as the visceral pleura

visceral means organ

it's actually touching the lungs now

again the pleural membranes have this

serous fluid what we call this in the

lungs pleural fluid that spill

spills over into that area to fill them

that way that it's lubricated whenever

you expand and contract

the last thing that you possibly want is

for the lungs to become

dry because then they won't expand easy

so what the pleural cavity does the

pleural membrane is going to

secrete pleural fluid to keep them moist

that way they can continue to expand and contract

contract easily

now it's important that you understand

when we are breathing

in and out of the lungs why we're able

to actually do that

the first process of respiration of

course is pulmonary ventilation is

breathing in and out

this consists of two phases we call them

inspiration or inhalation which is

bringing air into the lungs

or expiration or exhalation move air out

now how does it work well it works

because you've got this

relationship between pressure and volume

we say that pressure and volume

are inversely proportional that means as

one goes up the other goes down

and what we're describing here is

something called boyle's law

boyle's law states that if the

temperature is constant the number of

gas molecules

the pressure and volume are inversely

related such that

as the pressure increases volume

decreases as the volume decreases the

pressure increases

so they show you a little picture here

of a syringe

and what's happening is as the volume in

the syringe

increases the pressure is going to

decrease because the molecules are not

as close together the volume is greater

when you increase the pressure volume is

decreasing because there's not much

space left in there when you do that so

this is how your lungs work

the lungs what they do they decrease the pressure

pressure

whenever you breathe in to allow

molecules to come in from the outside they

they

increase the pressure when you breathe

now pulmonary ventilation involves

volume changes

and the lungs that lead to creation of a

pressure gradient that means a difference

difference

a difference on the inside versus the

outside that gradient

is going to cause air to move in and out

of the lungs

now inspiration takes energy it takes

energy for you to breathe because

your lungs are not going to really want

to do that by themselves but

expiration does not require muscle contraction

contraction

you're just going to decrease the volume

it's going to ah right that's actually

uh fairly energy efficient so when you're

you're

breathing in your diaphragm contracts

your external intercostals contract that

takes energy but whenever you expire

it actually relaxes them so it takes a

lot less energy to do that so

fixed energy does not take energy

now how this actually works is that it's

actually quite simple

it's very very small even a very small

um difference what we have to do

is that wherever we're at on our planet

whether it be right here on the surface

or in the clouds in front of a plane or

over the mountains where we got to do

we have to counteract

the atmospheric pressure the atmospheric

pressure is the pool of gravity around

us at sea level where we're at now

it's about 760 millimeters mercury this

increases below sea level and decreases

above sea level so as we go higher in

the mountains

it's harder to to breathe because you

have to try

to get that pressure even lower so it's

harder to breathe it'd be actually

easier to breathe

below sea level um people in new orleans

probably have a really good time breathing

breathing

because they're below sea level and it's

easier for them so they can

that's why they have those parties and

hooping the hollering because

they have a lot more energy i'm just kidding

kidding

but um you have to be able to to lower

that now

you have your own pressure this is

called intrapulmonary pressure

this is the air pressure within alveoli

this rises and falls when you breathe

but it will always equalize out with

atmospheric pressure at equilibrium so

this is how you

because you're going to equalize that

pressure you also have some interpol

or pleural pressure this is that a

pressure within the pleural cavity

it rises and falls inspiration

exploration but never equalizes

this keeps your lung from collapsing so

your lung

no matter what you've got in it should

never collapse but it's about four

millimeters below

intrapulmonary pressure which keeps your

so what happens whenever you do breathe

in again you see those differences

they're just barely even noticeable

but at atmospheric pressure at sea level

760 millimeters mercury also known as

one atmosphere

uh you have to decrease the

uh pressure to be able to breathe air

in decrease it by what we'll look there just

just

two just two two millimeters mercury

that's enough

to put air into your lungs to

get it out we have to increase it well

to what oh just two more

762. so you only change about four

millimeters mercury any time you take a breath

breath

it really isn't that much it really

should never be hard hard for you to

breathe because that's such a small change

change

now at the same time if your atmospheric

pressure is lower

you have to work even harder to get it

lower that's why it's harder to breathe

as you go up the mountain or on a plane

that's going to give you those masks

if it falls out whenever your

atmospheric pressure is decreasing

in in the cavity i mean in the cabin of

the plane

because what will happen is that you

will pass out from lack of oxygen

because the pressure is

you won't really get enough so they give

you this oxygen mask to make sure you

don't pass out

from the black so if cabin pressure

cabin pressure should be about the same

as the air on the ground

uh but if it's not then you you know if

it falls to where it is actually up

up in the atmosphere which is way less

than it is at the ground then you have

to have this oxygen mass

to prevent you from passing out from

lack of oxygen

now putting it all together uh

intracellular pressure equals

atmospheric pressure between breaths

when you inspire your muscles contract

thoracic volume increases lung volume

increases pressure decreases

when you expire muscles relax

lung volume decreases pressure increases

air flows in during inspiration

now what things can actually affect

how much air we breathe in and out well

one thing is that airway resistance so

anything's in the way

like a piece of bread that you choked on or

a mucus from a sinus infection

those things airway resistance something

in the way is what we call airwave resistance

resistance

alveolar surface tension alveolar are

covered with a symptom of liquid

uh mainly water to create a gas water

boundary so that they don't collapse

if the surface tension in the alveolar

has changed it can

prevent you from breathing that's what

happens a person's got copd they feel

like can expand anymore

and then pulmonary compliance is your

lungs able to

stretch and and be able to actually get

larger if they're not then of course

so first one airway resistance this is

determined by airway diameter

the diameter of the bronchioles is

controlled by smooth muscle contraction

so when they relax bronchi dilation

increases the diameter of the bronchials

decreases airway resistance increases airflow

airflow

but most of the time this is what's

going to be happening whenever a person

is breathing

most of the time we won't have anything

in our way because we'll feel that but

you can actually relax and contract

the uh the bronchioles to increase or

decrease the diameter of them

and that in which case it will increase

or decrease airflow

now this is what happens when a person has

has

an asthma attack what happens when an

asthma attack occurs is that

the diameter of the airway is going to

close up

and they're not going to get any air so

that could kill them

if they pass out and they're not helped

during that time so an asthma attack

could be brought on you know stress

or uh it could be brought on by

allergens things like that can bring

bring one on um that's what's going to

happen is that you're going to constrict

your airflow and it's again it's just

it's a

reaction that occurs because some kind

alveolar surface tension is another

factor now again a gas

water boundary exists within every

alveolus where the water molecules form

hydrogen bonds

due to partial charges but the gases are

nonpolar so therefore they do not form

hydrogen bonds so what you should have

is this film of water kind of pushed out

in the side of the alveolus so what that does

does

is to make sure your vli don't push together

together

you want to keep them inflated so this

creates surface tension the

gas water boundary when i feel after

small diameter and expiration

so it keeps them from collapsing but if

you have

high up under post surface tension that

will cause your alveoli to

fold or collapse during expiration we

call that telectassis

that's what happens whenever a person's

got copd they can't

contract them anymore because they

collapse because of the amount of

surface tension surfactant is what

goes against that surfactant is lipidy

it's liquid

and it coats the cells of the velous and

prevents the water from getting together

so it hopefully it'll push the water

molecules far enough apart

to where they create a tint surface that

will allow that avila to stay

open without surfactant which is again

again damaged by cigarette smoking

your vlog will collapse so that's that's

one of the

many many many reasons why cigarette

smoking is bad for you and we're not

talking about lung cancer

this is just about alveolar surface

tension this is something that's caused

by smoking

that has nothing to do with cancer and

this is about emphysema and copd

they also cause lung cancer which can

also kill you so

if you are a smoker i implore you please

try to do something else

vaping or whatever it is you know to get

you know that stuff

it's bad for you and it is really really horrible

horrible

and uh i know it's probably hard to quit

i'm sure i've never done it but i'm sure

it's hard to quit

but there are things you can do you know

to do that

it's it's a very very very very destructive

destructive

um dangerous habit and i wish you the

best in trying to quit that

so this is what would happen if you

didn't have surfactant

you would clap your vli with surfactant

you keep it inflated

so when a person's got emphysema the

surfactant kind of goes away and the

villa surface tension is you're not able

now the next factor that affects

pulmonary gas exchange is pulmonary compliance

compliance

this is the last physical factor that

influences the effectiveness of gastric exchange

exchange

all this is basically is the ability of

the lungs in the chest wall to stretch

and this is determined by a couple of

things one the degree of alveolar

surface tension

increasing surface tension resists the

ability of the velocity to inflate

the casing compliance so if your

available surface tension is increased

then you can't we can't fluff up anymore

distance ability elastic tissue gives

the lungs ability to stretch during

inflation increases compliance

the ability of the chest wall to move

increases compliance

so if the compliance decreases and the

lungs are ex less able to expand

you can't get enough air in so any of

these things will decrease compliance

so gas exchange is going to bring new air

air

into and remove oxygen poor air from the alveoli

alveoli

carbon dioxide is the waste product of

gas exchange and you want to get rid of it

so during pulmonary gas exchange oxygen

diffuses in from the air in the vela to

the blood and the pulmonary capillaries

carbon dioxide flows in the opposite

direction we're going to get rid of it

now the good thing about it is that they

actually don't compete for anything

they don't form bonds together and they

don't compete for space and hemoglobin so

they really don't even really notice

each other if they do they bump into

children and say uh i don't know you

keep on going so they don't there's no

problem with having oxygen or carbon dioxide

dioxide

in a given place because your body does

not they don't compete for anything

which is good now the the pulmonary gas

exchange involves exchanging the gases

between the alveoli in the blood

the tissue gas exchanges occurs at the

tissues in the body's systemic

capillaries in the body's cells

so you got two places where gas exchange

occurs one's in the lungs

the others in the tissues now what we

call pulmonary gastric exchange we call

that external respiration

this is the diffusion of gases between

alveoli and the blood

now again what's happening is that

oxygen goes in as carbon dioxide goes out

out

you can see the picture here so you

breathe in oxygen that's the red in the

picture here

and it's going to leave the alveolus and go

into the bloodstream carbon dioxide can

leave the bloodstream and go into the alveolus

alveolus

so going opposite directions so the pressure

is what's going to drive this so as

movement with all gases the pulmonary

gastric chain is driven by pressure changes

changes

you have a lower pressure on one side of

the membrane than you do on the other one

one

so the pressure gradients is created by

the difference in partial pressures of oxygen

oxygen

and carbon dioxide between the air and

the uv light and the blood and the

pulmonary capillaries

so if you look at the two graphs here

the one in red is the oxygen

the pressure in the alveolus is great

the pressure opponent capital is low how

does air flow from high pressure to low

pressure look at the pressure carbon dioxide

dioxide

it's actually lower in the uv less it is

in the prolonged capillary so again it's

going to go from high to low

now granted not a whole lot

lower now i want you to i want you to

answer this room it tells you here that

carbon dioxide's got a low pressure

gradient but a high solubility

um why do you think that it's more important

important

to have a high pressure of oxygen here

than it is for carbon dioxide think

about what oxygen does for you how

important it is

and tell me as your second disc question question

question

why do you think right here at the at

the alveolus you have a

higher pressure of oxygen than you do

now what can actually affect the

efficiency of pulmonary gas exchange well

well

one thing is the surface area of the

um restaurant membrane you have to have

a lot of surface area to be able to get

a lot of a lot of blood in there so

the the surface area is actually large

about a thousand square feet

whereas the quantity of blood

capillaries is about 100 milliliters

so any factor that reduces surface area

decreases efficiency pulmonary gas exchange

exchange

the thickness of the respiratory membrane

membrane

which is the distance to the mass that

uh gas must

diffuse now what can change that well

normally it's thin but anything that

increases the thickness like inflammation

inflammation

will diminish gas exchange especially if

you've got

some kind of water in there where would

the water come from

well the water would come from bacteria

in your lungs from pneumonia that's why

pneumonia kills you pneumonia diminishes

your capacity to get air into your lungs

when you've got pneumonia in your lungs

you're blocking it and if you block it

you die you know i knew a woman

um gosh it was a long time ago now she

was a friend of mine

in college that died of pneumonia she's

only 29.

she died of pneumonia because

she smoked you know heavily and wasn't

able to fight off bacteria

and died of pneumonia at 29 years old so

it was

terrible now ventilation profusion matching

matching

or coupling meaning that the degree of

match between the amount of air reaching

the vehiline amount of blood flow

that's important because that needs to match

match

the changes in the vehicle ventilation

lead to changes in perfusion the blood

flow is directed to the areas with most oxygen

oxygen

if you change it then air flow is

distributed to areas with most flow

the combination of these ensures that

ventilation and perfusion match or at least

least

are a couple closely to each other so

what that means

and let me just sum that up for you that

means that

your blood is going to go

to an area that's got the most oxygen

so it can pick it up so

you'll have more in there so you don't

want to you don't want to put blood into

a tissue when there's no oxygen in that blood

blood

you want to make sure that all the all

the oxygen is is carried

correctly that's what that means and tissue

tissue

gas exchange is called internal

respiration what's happening here again

is that the partial pressures of carbon dioxide

dioxide

and oxygen are using that gradient to

diffuse in and out of the tissues

so the cells use oxygen constantly for

slow respiration so the

the partial pressure of oxygen and

tissue is low while the pressure

pressure instead of capillaries is high

and again what that does is to allow the

oxygen to go

into the tissues again from high to low

pressure so that's that's the way that

you get you get oxygen into your tissues

is that the oxygen pressure is higher in

the capillaries

than it is in the tissue cells that will

diffuse easy

now they also produce a lot of carbon

dioxide which is a waste product

partial pressure is relatively high or

it's low in systemic capillaries again

this is going to

favor the diffusion of carbon dioxide

into the tissues from the tissue from

the tissues to the capillaries

that's how you're able to push carbon

dioxide out of your tissues into the

now again there are certain factors that

will that will affect tissue gas

exchange as well

one is the surface variable available

for that

uh if it large enough to allow gastric

chains efficiently

the distance again if you have a less

distance it results in more deficient

gas exchange

some of our uh organs are actually so

far away from

tissue gas exchange they don't get very

efficient gas exchange that includes

like your skin things like that

also the perfusion the tissue the more

blood you have in it the more efficient gas

gas

exchange you have the less blood you

have in it the less

so example for example cartilage

cartilage does not have very much blood

supply therefore

cartilage does not have good profusion

therefore it takes a long time for a

tear and cartilage to heal

because you don't have any blood in

now how is how are gases transported in

our blood

well in order for pulmonary and tissue

gas exchange to occur

oxygen and carbon dioxide must undergo

chemical reactions that allow for these

poorly soluble gases to be

transported safely what does that mean

well that means that you have to find a

way to

safely transport your gases in the blood

so they don't harm you

oxygen is transported mostly bound to hemoglobin

hemoglobin

hemoglobin are proteins that have oxygen

bounds and they're bound to the iron of

the protein

and about 1.5 percent is dissolved in

blood plasma

but oxygen is very is not soluble it's

very poorly soluble

so it doesn't dissolve easily in blood

plasma so

majority of it is stuck to hemoglobin

and it's red

so my blood is red that's why mars is

red that's why breast is red

anytime iron hits oxygen it's red so

that's why you have that color

carbon dioxide there are three ways the

carbon dioxide can be

can be transported including as a

bicarbonate ion

now oxygen is transported in the blood

bound to hemoglobin hemoglobin

is a protein a very large protein that's

found in red blood cells

basically all they are just little bags

of little bags of hemoglobin

each one's got a heme group that's got

an iron atom each one of those can bind

to a molecule of oxygen each one's got

four of them so

each hemoglobin molecule can bind to

four oxygen molecules which allows you to

actually take a lot of oxygen through

the bloodstream to the different cells

in your body

the oxygen and iron together it's red

so the hemoglobin pigment turns the blood

blood red

oxygen is transported through the

bloodstream down the hemoglobin now

what's happening

the partial pressure of oxygen is

pushing the oxygen through

the uh tissue wall into the bloodstream

and what's happening

is that as the blood cells are going by

it's popping onto it it's hitting it

so the oxygen is binding to the

hemoglobin in which it will go

into the tissues so it travels all the

way through

and it goes to the tissues and when it

gets there

the pressure is going to change it's

going to be a higher pressure

it's going to go to lower pressure so

the pressure of oxygen is higher in the

capillary is going to diffuse off into

the tissue cells

so tissue cells have lower oxygen than

the capillaries it's going to

go the opposite direction so it's going

to pop on in the

in the alveolus to the blood to the

blood cells that's going to pop off the

blood cells

oxygen bound to hemoglobin we call that

the percent saturation

the hemoglobin saturation depends on two

things one of course is the pressure of

oxygen in both lungs and tissues if you

have a high pressure it's going to

bind to it easier or the affinity the tightness

tightness

the bond strength which hemoglobin binds

to oxygen you can

change that you can change the affinity

of hemoglobin for oxygen

one is by increasing temperature that

can change it

also increase increasing hydrogen ion

concentration that increases the ph of blood

blood

so that can also affect it so you don't

want to have a blood ph it's above or

below 7.35 7.45

if you have that then the hemoglobin's

affinity for oxygen can decrease and it

can kill you

and as tissue produce atp the partial

pressure of carbon dioxide increases

all of that can actually affect the

hemoglobin d for oxygen and result in

unloading oxygen into tissues

now carbon dioxide is transported

through the blood in different ways this is

completely different than oxygen now

good the good thing about this

is that it does not compete with oxygen

part of carbon dioxide about seven ten

percent of total carbon dioxide

is produced specimen metabolism is

transported dissolved in blood plasma

which is way more than oxygen oxygen's

about one percent

it's also bound to hemoglobin about 20

percent is total

bounded hemoglobin uh it doesn't bind to the

the

the heme group though it binds to the

peptide chains we call this carbomedia hemoglobin

hemoglobin

so some of it does stick to the

hemoglobin but not the same part as oxygen

oxygen

some of it's in the blood plasma now why

do you think

that the majority of it is not in blood

plasma well

think about when you have like a

coca-cola and you shake it up

what would happen if your blood did that

you had carbon dioxide well then it

would poof

you know it would it fills up we don't

do that we don't want to do that so

that's how we're able to

to uh dissolve it in plasma

now the bicarbonate ion is how most of

it's going to going to uh

effect it's going to be transported in

the blood in the form of bicarbonate ion

which is not the form of co2

and that's very important in maintaining

your ph homeostasis in your blood

how this works is that when carbon

dioxide diffuses into your blood cells

it encounters an enzyme called carbonic

anhydrase and what that does

is to catalyze this reaction carbon dioxide

dioxide

in water is going to form what we call

carbonic acid

carbonic acid then is quickly converted

into bicarbonate ion and a hydrogen ion

now here's the thing hydrogen ion by

itself is like an unruly teenager

it does not like to be told what to do

does not like to be controlled

so what you've got to do you have to be

able to

make sure that that does not get out of

hand you got to control it

so what you have to do is that the hydrogen

hydrogen

bounds to hemoglobin if you didn't do

that then it would cause your blood ph

to become very acidic it would lower it and

and

it could kill you so hemoglobin says

real change

i'm gonna smack you and it takes the

hydrogen ion says hey

hold on to that well because you have a

hydrogen ion hanging out there bound to

hemoglobin you also have a negatively

charged bicarbonate ion hanging out there

there

well when you have a negatively charged

ion that leaves the

the blood cell and goes out into the

blood plasma that creates

a balance imbalance a charge imbalance

so what happens is that chloride ions

that are present in your bloodstream

are going to shift into the blood cells

to balance out the charges we call that

a chloride shift

a change in charge like that of your

cells and expect it to be okay

because you've got to balance out the

charge otherwise you have too much

father too much negative in any place

now carbon dioxide travels through the

bloodstream mostly

again mostly in the bicarbonate ion well

what happens when it gets up to

the alveoli the carbonic acid is

reformed the hemoglobin

lets go that unruly teenager that

hydrogen ion

and it's going to reform carbonic acid

with carbonic anhydrase that's going to

then put it back into carbon dioxide and

water then it can just spit it out

so carbon dioxide that point is free to

go so

it leaves your cells as carbon dioxide

it travels in your blood is bicarbonate

then it goes back into your alveolus as

carbon dioxide where you exhale it

so you reform it isn't that cool

now how do we change that

well changes in partial pressure carbon

dioxide hydrogen ions and partial

portion of oxygen are all stimulants for ventilation

ventilation

if you change any of these things your

amount of

is going to change so the major

determinant the one that's most

important is the pressure of carbon dioxide

dioxide

i know you guys think that oh well we

breathe in because we need oxygen for

our cells

really what you're actually trying to do

is not have too much carbon dioxide

so you got to breathe in to to actually

to control that so the the

carbonic acid is determined for hydrogen

ions and therefore blood ph so the

pressure carbon dioxide is the major

determinant for the blood ph

so that's really what controls your it's

the carbon dioxide not the amount of

oxygen you need it's

that's not really what it is um

so a change in normal pattern

ventilation can have a dramatic impact

on blood

concentration of hydrogen ions the more

you breathe in

the higher oxygen content you have lower

carbon dioxide you have

lower ph so if you're hyperventilating

that's bad for you so they tell you to

breathe into a paper bag

so you won't get too much oxygen in

there because if you do that you can you can

can

so again hyperventilation increases the

amount of carbon dioxide expired from

the lungs

so what that does is cause the ph of

blood to rise it causes because

become more basic and that leads to

alkalosis which is bad for you

if your blood ph increases because of

carbon dioxide

increasing then you can have a blood ph

that can

harm you hypoventilation

meaning you decrease the amount of

breathing causes more carbonic acid to

form and less

carbon dioxide which can lead to what we

call hypoxemia

so the oxygen levels drop that causes acidosis

acidosis

your blood becomes too acidic both of

these are really bad for you because

what happens

is when you've got an increase or

decrease in blood ph

your blood starts reacting with stuff

that it shouldn't be reacting with so

the the blood does not do what it's

supposed to do the affinity for

hemoglobin is messed up and then you

can't breathe and then you die

so acidosis and alkalosis caused by hyper

hyper

hypoventilation can kill you so when

somebody's hyperventilating

they put a paper bag so they don't so any any

any any

any they won't get too much oxygen you

know so that's what they're doing with that

the way to remember kind of what's going

on hyper means

above hyperventilation means you your ph increases

increases

hypo means below your ph decreases so if

you hyperventilate your blood ph

rises if you hypoventilate your blood ph decreases

decreases

now the lower the ph the higher the

hydrogen ion concentration and vice

versa so that's what that's telling you

and again having too much hydrogen ion in your body

in your body is bad

now unfortunately unlike our hearts which we talked about already in amp2 we

which we talked about already in amp2 we we actually have to control the group of

we actually have to control the group of uh breathing with our um

uh breathing with our um our brain so you have what we call

our brain so you have what we call euphenia which is normal breathing

euphenia which is normal breathing breathing occurs without conscious

breathing occurs without conscious thought of control you

thought of control you do it even though you don't know you're

do it even though you don't know you're doing it you have to do it no matter

doing it you have to do it no matter what

what but your brain does control it it's

but your brain does control it it's controlled by

controlled by neurons down the brain stem the pontine

neurons down the brain stem the pontine respiratory group which you've got in

respiratory group which you've got in here what we call a respiratory rhythm

here what we call a respiratory rhythm generator

generator this creates basic rhythm for breathing

this creates basic rhythm for breathing in addition to that you got other things

in addition to that you got other things negative feedback loops and stretch

negative feedback loops and stretch receptors in the lungs ensure oxygen

receptors in the lungs ensure oxygen intake

intake and carbon dioxide elimination match

and carbon dioxide elimination match metabolic requirements

metabolic requirements what does that mean that means that uh

what does that mean that means that uh you are breathing in oxygen breathing

you are breathing in oxygen breathing out carbon dioxide

out carbon dioxide and if you need more of that that's

and if you need more of that that's going to tell you

going to tell you breathe harder you know sometimes you'll

breathe harder you know sometimes you'll do that sometimes you'll sit there you

do that sometimes you'll sit there you go

go like that that's because your body says

like that that's because your body says all right i need some more you're not

all right i need some more you're not giving me enough

giving me enough you're not breathing hard enough

you're not breathing hard enough now again there is some voluntary

now again there is some voluntary control or ventilation supplied by

control or ventilation supplied by cerebral cortex

cerebral cortex which can override or bypass respiratory

which can override or bypass respiratory centers what that means

centers what that means is you actually can make yourself

is you actually can make yourself breathe in more if you choose to do that

breathe in more if you choose to do that you can also make yourself stop

you can also make yourself stop breathing as

breathing as you know you can hold your breath for a

you know you can hold your breath for a little while and then eventually that

little while and then eventually that will pass over and you will

will pass over and you will have to breathe again so it's like when

have to breathe again so it's like when you're when your little boy or girl says

you're when your little boy or girl says i'm going to kill myself you don't do

i'm going to kill myself you don't do what i want i'm going to stop breathing

what i want i'm going to stop breathing good luck with that

good luck with that all right uh it ain't going to work

all right uh it ain't going to work they're going to if

they're going to if they do pass out they're going to come

they do pass out they're going to come back up you know in a moment so you

back up you know in a moment so you cannot do that

cannot do that your brain will override that so that's

your brain will override that so that's not a way to

not a way to to commit suicide it ain't going to work

to commit suicide it ain't going to work that way

now the controls again that we use for this

this cerebral cortex is voluntary control

cerebral cortex is voluntary control they also have some changes in arterial

they also have some changes in arterial concentration of hydrogen ions changes

concentration of hydrogen ions changes in

in pressure of carbon dioxide and changes

pressure of carbon dioxide and changes in pressure of oxygen

in pressure of oxygen you have that picked up by receptors

you have that picked up by receptors chemoreceptors central receptors

chemoreceptors central receptors peripheral scepters

peripheral scepters and they tell your the ponds what you

and they tell your the ponds what you see here

see here you see that the pontine respiratory

you see that the pontine respiratory groups which you look at in the picture

groups which you look at in the picture here the brain stem

here the brain stem and that's going to carry out a message

and that's going to carry out a message that tells your breathing to increase or

that tells your breathing to increase or decrease

decrease alright so i would like you to tell me

alright so i would like you to tell me what you thought was most interesting

what you thought was most interesting about this chapter as your third and

about this chapter as your third and final discussion

final discussion question

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YouTube Transcript:Chapter 21 Lecture

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Chapter 21 Lecture