0:12 now this is actually one of the more simple
0:14 simple
0:16 uh body systems and anatomically there's
0:18 not a whole lot to this actually there's
0:20 only a few parts you can see it all
0:21 right here on the diagram
0:23 uh the organs that are included in the
0:25 respiratory tract and lungs
0:28 uh the nasal cavity nose pharynx larynx
0:31 the lungs trachea bronchi those are the
0:32 things that are going to be included in
0:34 this particular
0:37 body system it also includes the
0:39 includes the blood vessels the pulmonary
0:40 circuit the rib cage
0:43 and the muscles that allow your rib case
0:45 to expand and contract
0:47 mostly what you have in your respiratory
0:49 system are hollow pathogens
0:52 passages what they do is to exchange gases
0:53 gases
0:54 so each component of the tract has
0:56 unique growth and histological
0:58 uh structure and includes all those
1:04 now we can divide the respiratory system
1:05 up into what we call the lower
1:07 respiratory tract and the upper
1:08 respiratory tract
1:10 the upper respiratory tract are just the
1:12 passageways the air takes to go from
1:14 your nasal cavity to your larynx
1:16 the lower respiratory tract is going to
1:18 be where it actually exchanges gases
1:19 with your blood
1:21 so we're talking about your alveoli and
1:23 your lungs the vli
1:25 are little grape like clusters where
1:27 their gases are exchanged
1:28 with the blood carbon dioxide oxygen are
1:30 going to be exchanged
1:32 at this point the lungs are the places
1:33 that house them
1:35 they're spongy organs in the thoracic
1:37 cavity they're enclosed in the
1:38 boundaries of the ribcage and your diaphragm
1:40 diaphragm
1:43 and each one of those is a collection of
1:44 millions of alveoli
1:46 how many millions 150 million of you
1:48 allow that's the number actually i mean
1:50 there actually are inside there
1:53 and what they do is to expand whenever
1:55 air comes in and what's going to happen
1:57 at the alveolus is you're going to give
1:59 oxygen to your blood and take carbon
2:07 so we classify the respiratory system
2:09 based on some some zones we classify
2:11 them based on what they do
2:12 functionally into conducting and
2:14 respiratory zones the twos of the
2:16 conducting zones are just places where
2:18 the air travels whenever you inhale it
2:20 or we call that inspiring
2:23 or you exhale it or expiring majority
2:27 of the surface area of the respiratory
2:29 system is just that conducting zone
2:31 so as it comes to the conducting zone
2:33 it's filtered it's warmed and it's moistened
2:34 moistened
2:35 and this includes all the structures
2:37 from your nose all the way down the
2:38 bronchial so the
2:40 majority of this is in fact conducting zone
2:41 zone
2:43 the respiratory zone where gas exchange
2:45 occurs only little bitty structures that
2:47 are in the alveoli
2:50 so the respiratory zone is by the
2:51 surface area
2:53 very small compared to your conducting zone
3:00 now what respiration is is actually
3:02 a combination of four separate processes
3:04 this is the function
3:06 of the respiratory system and now why is
3:08 that so important because what it does
3:12 is to give our body oxygen and take away
3:13 wasteful carbon dioxide
3:14 so there are several different ways this
3:16 can occur and this all works together
3:19 pulmonary ventilation is the movement of air
3:20 air
3:22 into and out of the lungs that's the
3:24 that's that
3:26 pulmonary gastric exchange this is what
3:28 occurs in the lungs and the blood
3:31 so the gas carbon dioxide and oxygen are
3:32 be exchanged
3:34 in the lungs that carbon dioxide and
3:35 oxygen is also
3:37 transported through your blood we call
3:39 that gas transport and it makes its way to
3:40 to
3:43 your tissues tissue gas exchange is the
3:44 movement of gases
3:51 now what else does your respiratory
3:52 system do
3:54 well it also has some other functions
3:56 you have the mechanism for speech and
3:58 sound production that's how i'm talking
3:59 to you right now
4:00 what's happening is whenever you are speaking
4:02 speaking
4:04 air is being pushed across your larynx
4:05 and that's going to vibrate
4:07 your vocal cords and then that makes
4:08 this noise that you hear
4:11 that's that all right so that's how we
4:14 are able to produce sounds
4:16 you also have neurons in your
4:17 respiratory system that are responsible
4:19 for a sense of smell
4:20 we talked about that at the beginning of
4:22 the semester
4:27 and it is possible and we know this
4:28 to expel contents from the abdominal
4:31 pelvic cavity to assist with defecation
4:33 urination childbirth by increasing
4:34 pressure and thoracic cavity
4:36 you guys know about that whenever you go
4:38 to pee or poop and you go
4:41 that straining that's got a name for
4:42 it's actually called the valsivars
4:45 maneuver and that's the pushing that you
4:46 do whenever you're
4:49 defecating or even when you're having a child
4:49 child
4:51 that pushing that's called the valsivars maneuver
4:53 maneuver
4:55 so that's your thoracic cavity changes
4:57 are helping you to do that
4:58 pressure changes in the thoracic cavity
5:00 also assists with venous blood flow and
5:01 lymph transport
5:04 so you guys remember the respiratory
5:06 pump we talked about that in the in the
5:10 lymphatic chapter that's going to be
5:12 working whenever you're breathing in and
5:15 out your respiratory system also
5:18 helps you to maintain acid base balance
5:21 very very important it can be disturbed
5:25 by changes in your breathing and also
5:27 we do synthesize an enzyme involved in
5:28 the production of angiotensin
5:30 which is going to help control blood
5:32 pressure and fluid homeostasis so the
5:33 respiratory system
5:35 very very important for your life
5:37 without it you would die
5:38 and we're going to talk about how it
5:41 actually works
5:44 now the nose and nasal cavity
5:45 are the entrance way into your
5:48 respiratory system and they
5:49 have some functions that are really
5:51 important for you one thing they do
5:53 is to warm the air if the air is too
5:55 cold to hit your lungs that can
5:58 cause some very unpleasant feelings we
5:59 had that before happen
6:01 it's also humidified you don't want your
6:02 lungs to dry
6:06 out from dry air so you have to humidify
6:08 that air as it goes in
6:11 debris is also filtered antibacterial
6:12 substances are secreted so
6:16 the debris is filtered from from the air
6:18 into your lungs that way you don't catch
6:19 something that may have brought in now
6:20 around here
6:21 that's actually really important because
6:23 we have a lot of peanut dust because of
6:25 the forming around here
6:28 you also have the olfactory receptors
6:30 housed here in the nasal cavity
6:32 and this is also enhancing the resonance
6:34 of your voice so the
6:35 fact that it's got some space in there
6:37 is allowing you to throw
6:45 that's what it looks like this is a model
6:46 model
6:47 i have one of these in the lab if you
6:48 want to check it out you're more than
6:50 welcome to do that
6:53 this is the model of the nasal cavity
6:55 so the air is going to enter the nasal
6:57 cavity which is a hollow space
6:59 frame by the bone and hyaline cartilage extends
7:00 extends
7:03 uh actually between two posterior nerves
7:06 so the nares are basically your nostrils
7:08 that's what we're talking about here so
7:10 the nasal cavity is actually divided into
7:10 into
7:13 left and right portions by the nasal septum
7:14 septum
7:17 now your first discussion question
7:19 i would like you to tell me why do you
7:20 think you've got
7:23 two places where air can enter you got
7:24 two nostrils
7:26 got two sides why do you think you have
7:27 two sides
7:29 why not just have one big hole to get
7:30 more air in why is there a partition there
7:31 there
7:33 what purpose do you think that serves to
7:36 have a partition in the middle of your nose
7:37 nose
7:38 so tell me why you think that's
7:39 important for you that's your first
7:41 discussion question
7:44 now the vestibule this is the most
7:47 anterior region of the nasal cavity just
7:48 inside the nostril you got
7:51 hairs here to prevent large objects from
7:52 entering your nasal cavity
7:54 you don't want big old things coming
7:56 inside there because it could it could
7:58 really damage the inside of your nose so
7:59 the hairs are there to protect you
8:02 they do fill up with you know mucus and
8:03 things like that
8:06 and and dust and whatever and it becomes
8:07 kind of gross but that's
8:09 there on purpose to stop that stuff from
8:13 getting inside your body
8:15 now the bony projections that you have
8:17 in the nasal cavity the superior
8:19 inferior and middle conkey
8:22 these are processes of the ethmoid bone
8:24 i talked about that back in amp1
8:25 the inferior concrete fill most of the
8:27 space in the nasal cavity now what these do
8:28 do
8:30 what they're doing here is to increase
8:32 surface area
8:35 so they're allowing passageways to
8:36 funnel the air
8:38 to the right spot that way it can be
8:40 humidified and
8:43 warmed and and it won't be so cold
8:45 all right so the conchi curl around for
8:48 your passageways we call these meatuses
8:50 so superior middle and inferior nasal meatuses
8:51 meatuses
8:53 this create turbulence that rids the
8:55 dust and debris from inspired air
8:57 so basically what happens here is that
8:58 the junk you breathe in
9:01 falls out right there because you don't
9:04 want it to go down any farther
9:06 now in addition to having these concrete
9:08 you also have sinuses
9:10 that's exactly what i'm talking about
9:12 that kind of sinus stuff that's
9:14 what that's caused by perinasal sinuses
9:16 are hollow cavities within several the
9:17 bones that you have in your skull
9:19 and they're connected to the nasal past
9:22 nasal cavity by small passageways and
9:22 what they do
9:25 is to help warm the air and enhance
9:26 voice resonance and reduce the weight of
9:27 the skull
9:29 however because they are lined with
9:31 mucous membranes
9:33 bacteria can become trapped there and
9:34 infect them
9:36 we get that fairly often here in blakely
9:37 because we have
9:39 like sinus infections because we have so
9:40 many things that are in the air around here
9:41 here
9:44 so sinus infections occur quite often in
9:45 our population
9:46 because of the fact we have so much
9:50 stuff in the air
9:52 now that should explain to you the
9:53 reason why
9:55 your voice sounds funky whenever you
9:57 have a sinus infection
9:59 because the sinuses if they're clogged
10:01 they don't work properly
10:03 and then the the function of the sinuses
10:04 is to give you a voice resonance so if
10:05 it doesn't work then
10:12 the nasal cavity the vestibulus line
10:14 with stratified chromos epithelial tissue
10:14 tissue
10:16 that resists mechanical stress because
10:17 stuff's hitting it all the time you're
10:20 breathing in air every second right
10:21 you also if you have to scratch your
10:24 nose that's why you have that there
10:27 behind the vestibule it changes to a
10:28 different type of
10:30 epithelial tissue olfactory mucosa and
10:32 respiratory mucosa
10:34 the olfactory mucosa is located on the
10:35 roof of the nasal cavity and this is
10:36 where you've got
10:38 receptors for this for the sense of smell
10:39 smell
10:41 it's actually kind of funny this is the
10:43 only place in your body where neurons
10:45 actually touch the outside
10:46 so the neurons are just hanging out
10:48 there waiting for stuff to fall on them
10:51 to stimulate your sense of smell this is
10:52 the only place in your body where a
10:54 neuron actually meets the outside of
10:55 your body and this is inside the
10:57 olfactory mucosa
10:59 the rest of the nasal cavity is lined with
11:00 with
11:02 pseudostratified cylindic chlorine
11:04 epithelium sorry about bringing
11:06 bad memories from ap1 i'm sure you
11:07 remember that it was the slide with the
11:08 tall cells
11:10 that looked that they were on top of
11:12 each other but they actually weren't um
11:14 and goblet cells which are inside that
11:15 what these do
11:19 is to trap particles in mucus
11:21 so the cilia help trap particles the
11:22 mucous substrate particles and it
11:24 prevents it
11:26 from going down any further in your
11:27 nasal cavity
11:29 so we don't want this to go any we don't
11:30 want to go down our lungs
11:32 back up so this propels the mucus
11:34 towards the back nasal cavity and the pharynx
11:34 pharynx
11:37 so that we can swallow it why would you
11:38 want to do that well
11:41 you swallow that junk because
11:44 your stomach acid is very very acidic
11:45 and it will destroy most of the things
11:47 that you put in there
11:49 so you don't want your you don't want
11:51 your nasal cavity to be
11:52 filled with that stuff because you can't
11:54 breathe and does ever happen of course
11:55 listen you hear that it's happening
11:58 right now so this is the
12:00 mechanism that your body uses to try to
12:01 get rid of stuff
12:03 that could potentially become irritated
12:09 now the pharynx is the next anatomical
12:10 segment of the respiratory tract that
12:11 inspired air
12:13 enters after exiting the nasal cavity
12:16 this is on the diagram here's the first
12:18 part that starts in blue
12:20 and you've actually got three parts to
12:21 this and they're listed right here on
12:22 the picture
12:23 nasopharynx oropharynx and
12:26 laryngopharynx this
12:27 nasopharynx that means it comes from the
12:29 nose this is the part
12:31 that is going to filter air towards the
12:32 back of your throat
12:33 the oropharynx is the part that's going
12:35 to filter water or food to the back of
12:36 your throat
12:38 lorenzo pharynx is going to go towards
12:40 your larynx
12:42 now what the nasopharynx does it's lined
12:44 with pseudostratified syllable
12:46 epithelium tissue to humidify
12:49 and filter inspired air so really
12:51 the best thing for you to be doing is to
12:53 be breathing through your nose if you
12:55 can because you don't get that same
12:56 protection if you breathe through your mouth
12:57 mouth
12:59 because you don't have that same cilia
13:00 and stuff doing it now stuff you still
13:02 have some protection you got tonsils
13:03 that are going to help filter but you
13:05 don't have the protection that your
13:08 nasal cavity offers
13:11 now the nasopharynx extends from the
13:13 posterior narrows the back part of the nostrils
13:13 nostrils
13:16 to the uvula the uvula
13:18 is that little soft thing that hangs
13:20 down what that does
13:23 it moves when you swallow and it covers
13:25 your nasal cavity so when you swallow
13:27 food should only go one direction and
13:29 that should be down
13:31 it should not come the other direction
13:33 now does it ever happen
13:34 sure think about back when you were a
13:36 child and you were something was funny
13:38 and you spilled milk out your nose yes
13:39 it happens
13:40 because you're trying to breathe and
13:42 talk and chew this all at the same time
13:42 right so
13:44 stuff happens but majority of time when
13:46 we swallow that's covered
13:48 so that we don't spill that food or
13:50 water whatever it is out our nasal cavity
13:51 cavity
13:53 water does not belong there the cells
13:55 that you have there
13:56 they don't like being wet from water
13:58 that's why it burns when you get
14:00 water up your nose this should not be
14:08 now oropharynx this is the next segment
14:10 this extends from the tip of the uvula
14:12 to the epiglottis and larynx
14:14 this is filled with non-keratinized
14:16 stratified squamous epithelium
14:18 which is more protective than your nasal
14:20 cavity that's why if you get
14:21 through your nasal cavity it's
14:22 irritating if you get food right here
14:24 it's no big deal this is what it's made for
14:24 for
14:26 this is a passageway for both air and food
14:28 food
14:30 lorenzo pharynx this is the last segment
14:32 and this extends from the highway bone
14:36 to the esophagus and the anterior larynx
14:36 opens to the
14:38 longer pharynx opens to the larynx or
14:40 the voice box the posterior opens into
14:42 the esophagus
14:45 now it is at this point here that you see
14:46 see
14:49 that it is entirely possible that we
14:50 start choking
14:52 in our design the way humans are
14:54 designed these two things are
14:58 really close together and
15:01 sometimes that is a problem
15:03 because sometimes we're trying to do something
15:04 something
15:05 at the same time we're trying to eat
15:08 like talk right so what happens
15:12 is that the the epiglottis which should
15:13 be covering up your
15:15 your larynx and your trachea during eating
15:16 eating
15:18 is uncovered and food goes down the
15:21 larynx and it should not be and so
15:23 because the cells of your larynx are
15:24 specialized to take in
15:27 air when something else touches them
15:28 other than air
15:31 it triggers a violent reflex to try to
15:32 get that
15:34 out that's coughing right when it
15:35 happens in your in your
15:37 nasal cavity it's sneezing it coughing
15:39 and sneezing actually initiated by the
15:40 same thing
15:42 and what should be happening anytime you
15:44 swallow is that the
15:47 the epiglottis should be covering up
15:49 the layering so the food passage down
15:51 the esophagus
15:53 now the esophagus has got the
15:54 specialized epithelium
15:56 that way it won't be damaged by food
15:58 that's being pressed down against it
15:59 we'll talk more about that in the next chapter
15:59 chapter
16:00 actually but for now i just want you to
16:02 know that
16:04 lorenzo pharynx is that last segment
16:05 that it goes from
16:13 and the larynx or voice box this is what
16:15 what's going to house your vocal cords
16:16 you've got a couple different types of these
16:21 what they do these are these are types
16:22 of cartilage
16:26 that are going to be in and
16:28 special elastic cartilage special types
16:30 of cartilage are going to be
16:33 vibrated to be able to produce sound
16:35 that's what's happening right now
16:37 uh you've got stratified squamous
16:39 non-keratinized epithelium
16:41 protects your your larynx from
16:43 mechanical stress to vocal cords where
16:45 food and air both pass through
16:47 and you've also got pseudostratified
16:48 facilitator epithelium which is found
16:51 behind or below the vocal cords which is
16:53 to propel mucus and debris up out of the
16:57 larynx as one goes
16:58 your people do that all the time and
16:58 that's what they're doing they're
17:00 clearing their throat that's that
17:04 that's that noise
17:06 this is what it looks like again cartilages
17:08 cartilages
17:10 sections of cartilage three paired three
17:12 unpaired and six paired
17:14 provide a framework it's got to be flexible
17:15 flexible
17:17 it's flexible because if you had no flex
17:18 flexibility there then everything would
17:20 sound just like this
17:21 you would never be able to and that
17:23 would be boring right some of you
17:24 probably think i sound like that anyway
17:25 but i really don't i promise
17:28 um the cricoid thyroid and ironic
17:30 cartilages are made out of hyaline
17:31 cartilage where the roast
17:33 rest of them are made out of elastic
17:35 cartilage your vocal cords actually are
17:37 made out of elastic cartilage and what
17:38 that's doing is
17:41 is changing shape to be able to produce
17:43 different types of sounds
17:46 so if you look at it from the front side
17:48 the thyroid cartilage there's a little tip
17:49 tip
17:51 i'm going to try to circle that with the
17:54 pointers you'll see it should be circled
17:57 on there a little tip come on
18:00 there we go uh it's in red i circled it
18:02 in red on the other that's called the
18:04 laryngeal prominence
18:06 that's the tip of the thyroid cartilage
18:08 that's your adam's apple
18:09 so that's a circle there for you on the
18:12 diagram the adam's apple is
18:15 the place that we have this thyroid cartilage
18:16 cartilage
18:18 it's named thyroid cartilage because
18:19 it's near thyroid gland
18:28 the trachea also known as the windpipe
18:30 it's actually a really interesting
18:32 structure the trachea has got a lot of
18:34 cartilage in it and it goes down
18:36 past your larynx all the way down to
18:38 your lungs it's going to divide there
18:42 and take air now the trachea
18:44 has got a lot of space you see that at
18:45 the bottom here it says lumen
18:48 of trachea that's the space what the
18:50 lumen does is to provide a passageway
18:51 for air
18:54 now look see how it's nice and open and round
18:55 round
18:58 look behind and you see the esophagus
18:59 esophagus is kind of smooshy
19:03 well the reason for that is because
19:06 you do not have to be eating every second
19:07 second
19:08 you do not need to have food in your
19:11 stomach all the time so the esophagus
19:12 can push take its time pushing through
19:14 there it's not going to kill you if you
19:15 can't eat
19:17 but it is going to kill you if you don't
19:19 get oxygen to your lungs
19:22 so the trachea must be
19:25 open at all times it has to be so
19:27 what you've got around it that you don't
19:29 have around the esophagus
19:31 are these cartilaginous rings they look
19:33 kind of like c's it's kind of a c-shaped ring
19:34 ring
19:36 they're supportive but they're also flexible
19:37 flexible
19:40 so you can change the amount of air
19:42 going into your lungs by changing
19:43 the flexibility of these rings so it
19:45 allows you to
19:46 it allows you to get bigger or smaller
19:52 when a person is choked or strangled
19:54 really this person is strangled
19:57 this is closed up because they can't
19:58 they can't uh
20:01 breathe because that's closed and it's
20:01 no fun
20:04 all right uh it's certainly unpleasant um
20:04 um
20:07 but that's what's causing a person to
20:09 pass out because they don't have any
20:12 air coming in the trachea now it it
20:15 it has a elastic connective tissue and
20:16 smooth muscle which allows it
20:18 allows the esophagus to span during
20:20 swallowing so
20:21 it's not completely covered with
20:23 cartilage because you got that smooth
20:25 muscle there right next to esophagus to
20:26 allow the esophagus to get a little bigger
20:27 bigger
20:30 so that's usually why actually it is why
20:30 you don't
20:32 breathe at the same time you take a
20:34 swallow of food because
20:36 you can't really and when you do joke because
20:37 because
20:38 you're not supposed to be doing that
20:40 because it's actually two things you
20:41 should not make occurring at the same time
20:48 now the trachea the last brachial
20:49 cartilage is called the carina this is
20:52 also forms a little hook that curves
20:53 down and back to the partial rings that
20:54 surround the first branch of the
20:56 bronchial tree
20:57 it's called bronchial tree because it's
20:59 got branches again if
21:03 you get something in there that is not
21:04 supposed to be in there
21:06 like something really solid really large
21:08 inside like water
21:10 or food items it's going to try to get
21:11 that out
21:13 by violent cough reflex it's going to
21:15 contract to try to get that out
21:18 so that's why you cough
21:21 the mucosa the trachea is again lined
21:22 with pseudostratified
21:24 epithelial tissue now what they do it's
21:26 actually kind of cool
21:27 what happens you see in this picture
21:29 here at the bottom left you see these
21:31 this tracheal tissue you see the the
21:32 cartilage and you recognize that from mp1
21:33 mp1
21:35 and you see the pseudostratified
21:37 epithelial tissue you recognize that
21:38 from mp12 i'm sure
21:42 but you also see the the the
21:45 linear at the top the linear projections
21:46 those are the cilia
21:49 the cilia are going to be pushing
21:52 the uh whatever's in them back up
21:54 towards the top of your throat you'll
21:54 swallow it
21:57 that includes bacteria viruses fungal
21:59 spores whatever it catches
22:01 it's going to push that up to the top of
22:03 your larynx so you'll swallow that
22:04 instead of
22:05 breathing it down to your lungs this is
22:07 a filtering function
22:09 and what that does is to get that stuff
22:10 in there so you'll swallow it and
22:14 not breathe it in because you do not need
22:14 need
22:17 fungal spores bacteria or viruses in
22:18 your lungs
22:20 does that ever happen yeah unless
22:23 pneumonia comes into play
22:26 but we would try not to have that happen
22:27 and what will happen is that you will swallow
22:28 swallow
22:30 that and kill it instead of making you sick
22:39 once the air reaches the carina
22:42 it can be pummeled to the left or right
22:45 primary bronchus again you've got two of
22:47 these in case one of them stops working
22:49 once inside the lung each bronchus
22:50 divides into a bronchial tree and it
22:52 gets smaller and smaller and smaller eventually
22:53 eventually
22:55 now the bronchial tree becomes smaller
22:57 the cartilage changes from c-shaped
23:00 rings to complete rings
23:01 and then finally you just have these
23:03 irregular type plates now the primary
23:04 bronchi is the first place where it divides
23:05 divides
23:07 left and right branches of the carina
23:09 they didn't divide into smaller
23:11 secondary bronchi
23:12 and then there's three on the right and
23:15 two on the left this is due
23:17 because of the position of the heart so
23:18 the lungs are not
23:20 perfectly symmetrical they actually look
23:22 different on the left side they do on
23:23 the right side because of the way your
23:25 heart's facing
23:28 the secondary branchy may branch into
23:29 into about 10
23:31 smaller tertiary bronchi prolong and
23:33 continue to branch into smaller and
23:35 smaller smaller branches until finally
23:41 the bronchials are the smallest airways
23:43 and their features are different from
23:44 larger airways
23:46 they have simple cuboidal epithelial
23:48 tissue with very few cilia
23:51 if any they have enclosed within the
23:52 thick ring of the smooth muscle
23:55 and there's no hyaline cartilage what's
23:57 happening here is that air is pushing
23:58 down to them
24:00 the conducting zone the respiratory
24:02 tract ends when inspired air reaches
24:05 terminal bronchioles that means the end
24:07 terminal bronchioles branch into two or
24:09 more two or more smaller respiratory bronchioles
24:10 bronchioles
24:12 surrounded by smooth muscle the
24:13 respiratory zone
24:16 begins with respiratory bronchioles with
24:18 a vli that are budding from the wall so
24:19 they look like a bunch of grapes and
24:20 what they're doing
24:23 is they're going to be the end result of
24:24 the breathing in
24:27 from your lungs each respiratory
24:28 bronchial has
24:32 ducts which have the alveoli attached
24:35 to their wall so the sacks the uv li are
24:37 like little grapes and the inspired air
24:39 has arrived where gas exchange is going
24:40 to occur so the
24:43 alveoli are these sacs that
24:45 that's going to be the respiratory zone
24:46 this is the only part of the
24:48 of your respiratory system that actually
24:50 where gas exchange does in fact take place
24:58 so it looks like visually the air comes down
24:58 down
25:00 for terminal bronchiole it hits the
25:02 respiratory bronchial and then you start
25:03 to have this
25:06 this uh push out of for
25:08 the alveoli so the vli are small little
25:10 grape like sacs
25:12 where the air is going to be pushed through
25:14 through
25:17 now this is the pathway of air so i'd
25:18 like to review this with you so you know
25:20 exactly which direction it goes i would
25:21 like you to know this for your for your
25:23 test i'm going to ask you about it
25:26 the airway goes from the nares to the
25:27 nasal cavity
25:29 to the narrow nasopharynx oropharynx
25:30 orange pharynx
25:32 from the larynx down to the trachea it's
25:34 the primary bronchi the splits in the
25:36 secondary tertiary and finally all the
25:38 different branches of the bronchi
25:39 it goes to the bronchioles smaller
25:41 terminal bronchioles even smaller
25:42 respiratory bronchioles
25:45 to the vehicle redux and finally to the
25:46 alveolar sacs which is where it's going
25:47 to be
25:49 exchanging gases with the blood so
25:51 definitely want you to know the order
25:54 of this it's very important that you understand
25:57 understand
25:59 now when you get to the alveoli the vli
26:01 are the final destination for inspired air
26:02 air
26:04 so the air's got several things and it's
26:06 got oxygen carbon dioxide
26:09 nitrogen majority of its nitrogen and
26:10 that doesn't really do anything this
26:10 just kind of
26:13 comes in and comes out but you do have
26:15 several different types of cells that
26:16 are going to
26:19 take that inspired air one is called a
26:21 type 1 alveolar cell
26:22 these are squamous cells that account
26:24 for about 90 of the cells in the velar wall
26:25 wall
26:27 they're very thin and they allow for
26:30 rapid diffusion of gases so the thin
26:34 kind of structure there
26:35 is for diffusion you see how close the
26:37 blood vessel is to the velous
26:40 so you can get through there now they
26:40 have a very
26:43 humongous amount of surface area which
26:44 increases this gas
26:48 exchange so this is again an example of
26:51 what they look like affects what it does
26:53 type 2 alveolar cells these are smaller
26:54 cuboidal cells
26:56 and they're only about 10 of the cells
26:58 in the velar wall this is responsible for
26:58 for
27:02 surfactant surfactant is kind of an oily
27:04 greasy type
27:06 chemical that helps reduce surface
27:08 tension on alveoli
27:10 so you don't want the violets to close
27:12 up that's the last thing you want
27:12 because it could
27:14 that's what happens a person's got copd
27:15 that close up you don't want it to
27:17 happen so surfactant is there to keep
27:19 that from from occurring
27:21 you also have and there are little blue
27:23 things here
27:25 alveolar macrophages they're mobile
27:27 phagocytes means they move around
27:28 they have to have some surfactant to
27:29 meal to move around if you don't have
27:31 any surfactant they stay stationary
27:34 what they do is to clean up and digest
27:36 any debris that may display down there
27:37 does that ever happen
27:40 of course it does especially if you smoke
27:41 smoke
27:44 but if you smoke then the tar itself
27:46 covers them and they can't move around
27:47 so they can't
27:54 the lungs the lungs consist of the
27:56 alveoli and everything that's around them
27:56 them
27:58 so the right and left lungs are
27:59 separated by the heart and immediate
28:01 stein in the middle part of your chest
28:03 the lungs inferior flat base rests on
28:05 the diaphragm
28:06 while it's apex sits just below the
28:08 clavicle they're actually
28:11 really large organs so the very top of
28:12 it is right below your probably right
28:13 above your collarbone
28:15 the bottom of it actually goes really
28:17 far down into your your cavity so far
28:18 down that sometimes people think they've got
28:19 got
28:21 kidney stones or appendicitis really is
28:23 your lungs messing with you
28:25 so they're actually very large organs
28:27 the front back and lateral surfaces are in
28:28 in
28:30 contact with the rib cage we call this
28:32 the costal surfaces that means cartilage
28:34 of the rib cage
28:36 um it's in contact with mediastinum we
28:39 call this the midi style surface
28:41 and of course like all the other all the
28:42 other organs we're going to talk about
28:44 you've got a hilum a hilum is a
28:46 depression found on the media style
28:47 surface where each lung where things
28:48 like blood vessels
28:50 nerves enter the exit the lung you got
28:52 these in your kidneys you got these in
28:52 your spleen
28:54 you got several of these throughout your
28:56 your organs
28:59 and finally the left lung looks a little
29:01 different than the right lung
29:03 it's got a cardiac notch what do you
29:04 think goes in there
29:06 well this is the place where your
29:08 heart's going to fit the cardiac notch
29:09 because the heart
29:11 is facing towards the left and down
29:13 that's why you got that there you have
29:14 that there to be able to
29:16 have the place where the hearts going to
29:18 indent into that cardiac notch
29:24 each lung is divided into lobes the
29:26 right one's got three lobes the lepens
29:27 only got two lups
29:29 again that's because of the space of the
29:32 heart the right lung has got a superior
29:33 middle and inferior lobe
29:35 and you got fissures that separate each one
29:36 one
29:39 the left lung is divided into superior and
29:39 and
29:41 inferior that's it they've only got an
29:42 oblique figure so they don't look the same
29:43 same
29:52 the lungs are found within the pleural cavity
29:53 cavity
29:56 the pleural cavity is a subdivision of
29:57 thoracic cavity
29:59 and this is located between your serous
30:00 membrane you guys remember from amp-1
30:01 serous membranes
30:03 are those membranes that cover things
30:04 like the
30:07 the uh heart and lungs to be able to
30:09 keep them from smashing into each other
30:10 whenever they move
30:13 so the parietal pleura so the outer
30:15 layer of serous membranes diffuse
30:17 the the rib cage diaphragm and other structures
30:18 structures
30:20 the highland the parietal plural turns
30:22 over itself to create the inner
30:24 membrane known as the visceral pleura
30:25 visceral means organ
30:27 it's actually touching the lungs now
30:29 again the pleural membranes have this
30:31 serous fluid what we call this in the
30:33 lungs pleural fluid that spill
30:36 spills over into that area to fill them
30:38 that way that it's lubricated whenever
30:40 you expand and contract
30:42 the last thing that you possibly want is
30:44 for the lungs to become
30:47 dry because then they won't expand easy
30:48 so what the pleural cavity does the
30:50 pleural membrane is going to
30:52 secrete pleural fluid to keep them moist
30:54 that way they can continue to expand and contract
30:54 contract easily
31:01 now it's important that you understand
31:03 when we are breathing
31:06 in and out of the lungs why we're able
31:08 to actually do that
31:09 the first process of respiration of
31:11 course is pulmonary ventilation is
31:12 breathing in and out
31:14 this consists of two phases we call them
31:16 inspiration or inhalation which is
31:18 bringing air into the lungs
31:22 or expiration or exhalation move air out
31:24 now how does it work well it works
31:26 because you've got this
31:28 relationship between pressure and volume
31:30 we say that pressure and volume
31:33 are inversely proportional that means as
31:35 one goes up the other goes down
31:36 and what we're describing here is
31:38 something called boyle's law
31:40 boyle's law states that if the
31:42 temperature is constant the number of
31:43 gas molecules
31:46 the pressure and volume are inversely
31:47 related such that
31:49 as the pressure increases volume
31:51 decreases as the volume decreases the
31:53 pressure increases
31:55 so they show you a little picture here
31:57 of a syringe
32:00 and what's happening is as the volume in
32:01 the syringe
32:04 increases the pressure is going to
32:06 decrease because the molecules are not
32:08 as close together the volume is greater
32:10 when you increase the pressure volume is
32:12 decreasing because there's not much
32:14 space left in there when you do that so
32:15 this is how your lungs work
32:19 the lungs what they do they decrease the pressure
32:20 pressure
32:22 whenever you breathe in to allow
32:24 molecules to come in from the outside they
32:24 they
32:26 increase the pressure when you breathe
32:33 now pulmonary ventilation involves
32:34 volume changes
32:36 and the lungs that lead to creation of a
32:37 pressure gradient that means a difference
32:38 difference
32:40 a difference on the inside versus the
32:42 outside that gradient
32:44 is going to cause air to move in and out
32:45 of the lungs
32:48 now inspiration takes energy it takes
32:51 energy for you to breathe because
32:53 your lungs are not going to really want
32:55 to do that by themselves but
32:58 expiration does not require muscle contraction
32:58 contraction
32:59 you're just going to decrease the volume
33:03 it's going to ah right that's actually
33:05 uh fairly energy efficient so when you're
33:06 you're
33:08 breathing in your diaphragm contracts
33:10 your external intercostals contract that
33:13 takes energy but whenever you expire
33:15 it actually relaxes them so it takes a
33:18 lot less energy to do that so
33:24 fixed energy does not take energy
33:27 now how this actually works is that it's
33:28 actually quite simple
33:32 it's very very small even a very small
33:36 um difference what we have to do
33:37 is that wherever we're at on our planet
33:39 whether it be right here on the surface
33:41 or in the clouds in front of a plane or
33:43 over the mountains where we got to do
33:47 we have to counteract
33:49 the atmospheric pressure the atmospheric
33:50 pressure is the pool of gravity around
33:52 us at sea level where we're at now
33:55 it's about 760 millimeters mercury this
33:58 increases below sea level and decreases
34:02 above sea level so as we go higher in
34:02 the mountains
34:05 it's harder to to breathe because you
34:06 have to try
34:09 to get that pressure even lower so it's
34:10 harder to breathe it'd be actually
34:11 easier to breathe
34:13 below sea level um people in new orleans
34:14 probably have a really good time breathing
34:15 breathing
34:16 because they're below sea level and it's
34:18 easier for them so they can
34:19 that's why they have those parties and
34:21 hooping the hollering because
34:24 they have a lot more energy i'm just kidding
34:24 kidding
34:27 but um you have to be able to to lower
34:29 that now
34:31 you have your own pressure this is
34:33 called intrapulmonary pressure
34:36 this is the air pressure within alveoli
34:38 this rises and falls when you breathe
34:40 but it will always equalize out with
34:42 atmospheric pressure at equilibrium so
34:44 this is how you
34:45 because you're going to equalize that
34:48 pressure you also have some interpol
34:50 or pleural pressure this is that a
34:52 pressure within the pleural cavity
34:54 it rises and falls inspiration
34:56 exploration but never equalizes
34:58 this keeps your lung from collapsing so
34:59 your lung
35:01 no matter what you've got in it should
35:03 never collapse but it's about four
35:04 millimeters below
35:06 intrapulmonary pressure which keeps your
35:12 so what happens whenever you do breathe
35:14 in again you see those differences
35:16 they're just barely even noticeable
35:18 but at atmospheric pressure at sea level
35:20 760 millimeters mercury also known as
35:22 one atmosphere
35:26 uh you have to decrease the
35:30 uh pressure to be able to breathe air
35:32 in decrease it by what we'll look there just
35:33 just
35:35 two just two two millimeters mercury
35:36 that's enough
35:39 to put air into your lungs to
35:41 get it out we have to increase it well
35:43 to what oh just two more
35:46 762. so you only change about four
35:47 millimeters mercury any time you take a breath
35:48 breath
35:50 it really isn't that much it really
35:52 should never be hard hard for you to
35:53 breathe because that's such a small change
35:54 change
35:58 now at the same time if your atmospheric
36:00 pressure is lower
36:02 you have to work even harder to get it
36:03 lower that's why it's harder to breathe
36:05 as you go up the mountain or on a plane
36:08 that's going to give you those masks
36:10 if it falls out whenever your
36:12 atmospheric pressure is decreasing
36:15 in in the cavity i mean in the cabin of
36:16 the plane
36:18 because what will happen is that you
36:20 will pass out from lack of oxygen
36:21 because the pressure is
36:22 you won't really get enough so they give
36:24 you this oxygen mask to make sure you
36:25 don't pass out
36:28 from the black so if cabin pressure
36:30 cabin pressure should be about the same
36:32 as the air on the ground
36:35 uh but if it's not then you you know if
36:37 it falls to where it is actually up
36:39 up in the atmosphere which is way less
36:40 than it is at the ground then you have
36:41 to have this oxygen mass
36:43 to prevent you from passing out from
36:45 lack of oxygen
36:52 now putting it all together uh
36:53 intracellular pressure equals
36:55 atmospheric pressure between breaths
36:58 when you inspire your muscles contract
37:00 thoracic volume increases lung volume
37:02 increases pressure decreases
37:06 when you expire muscles relax
37:08 lung volume decreases pressure increases
37:10 air flows in during inspiration
37:19 now what things can actually affect
37:23 how much air we breathe in and out well
37:26 one thing is that airway resistance so
37:27 anything's in the way
37:30 like a piece of bread that you choked on or
37:30 or
37:34 a mucus from a sinus infection
37:36 those things airway resistance something
37:38 in the way is what we call airwave resistance
37:39 resistance
37:41 alveolar surface tension alveolar are
37:43 covered with a symptom of liquid
37:46 uh mainly water to create a gas water
37:48 boundary so that they don't collapse
37:50 if the surface tension in the alveolar
37:53 has changed it can
37:54 prevent you from breathing that's what
37:56 happens a person's got copd they feel
37:58 like can expand anymore
38:01 and then pulmonary compliance is your
38:02 lungs able to
38:05 stretch and and be able to actually get
38:06 larger if they're not then of course
38:13 so first one airway resistance this is
38:15 determined by airway diameter
38:16 the diameter of the bronchioles is
38:18 controlled by smooth muscle contraction
38:20 so when they relax bronchi dilation
38:22 increases the diameter of the bronchials
38:23 decreases airway resistance increases airflow
38:25 airflow
38:26 but most of the time this is what's
38:28 going to be happening whenever a person
38:29 is breathing
38:30 most of the time we won't have anything
38:32 in our way because we'll feel that but
38:34 you can actually relax and contract
38:37 the uh the bronchioles to increase or
38:38 decrease the diameter of them
38:40 and that in which case it will increase
38:42 or decrease airflow
38:45 now this is what happens when a person has
38:45 has
38:48 an asthma attack what happens when an
38:49 asthma attack occurs is that
38:52 the diameter of the airway is going to
38:53 close up
38:56 and they're not going to get any air so
38:56 that could kill them
38:59 if they pass out and they're not helped
39:01 during that time so an asthma attack
39:02 could be brought on you know stress
39:04 or uh it could be brought on by
39:06 allergens things like that can bring
39:09 bring one on um that's what's going to
39:12 happen is that you're going to constrict
39:14 your airflow and it's again it's just
39:15 it's a
39:18 reaction that occurs because some kind
39:23 alveolar surface tension is another
39:25 factor now again a gas
39:27 water boundary exists within every
39:28 alveolus where the water molecules form
39:30 hydrogen bonds
39:32 due to partial charges but the gases are
39:34 nonpolar so therefore they do not form
39:37 hydrogen bonds so what you should have
39:42 is this film of water kind of pushed out
39:44 in the side of the alveolus so what that does
39:46 does
39:49 is to make sure your vli don't push together
39:50 together
39:52 you want to keep them inflated so this
39:53 creates surface tension the
39:55 gas water boundary when i feel after
39:57 small diameter and expiration
40:00 so it keeps them from collapsing but if
40:01 you have
40:03 high up under post surface tension that
40:04 will cause your alveoli to
40:07 fold or collapse during expiration we
40:09 call that telectassis
40:10 that's what happens whenever a person's
40:12 got copd they can't
40:13 contract them anymore because they
40:15 collapse because of the amount of
40:18 surface tension surfactant is what
40:21 goes against that surfactant is lipidy
40:22 it's liquid
40:24 and it coats the cells of the velous and
40:26 prevents the water from getting together
40:29 so it hopefully it'll push the water
40:30 molecules far enough apart
40:32 to where they create a tint surface that
40:34 will allow that avila to stay
40:36 open without surfactant which is again
40:38 again damaged by cigarette smoking
40:41 your vlog will collapse so that's that's
40:42 one of the
40:45 many many many reasons why cigarette
40:46 smoking is bad for you and we're not
40:48 talking about lung cancer
40:49 this is just about alveolar surface
40:51 tension this is something that's caused
40:52 by smoking
40:54 that has nothing to do with cancer and
40:56 this is about emphysema and copd
40:58 they also cause lung cancer which can
41:00 also kill you so
41:02 if you are a smoker i implore you please
41:06 try to do something else
41:08 vaping or whatever it is you know to get
41:10 you know that stuff
41:13 it's bad for you and it is really really horrible
41:13 horrible
41:16 and uh i know it's probably hard to quit
41:18 i'm sure i've never done it but i'm sure
41:20 it's hard to quit
41:22 but there are things you can do you know
41:24 to do that
41:26 it's it's a very very very very destructive
41:27 destructive
41:30 um dangerous habit and i wish you the
41:31 best in trying to quit that
41:38 so this is what would happen if you
41:40 didn't have surfactant
41:42 you would clap your vli with surfactant
41:43 you keep it inflated
41:46 so when a person's got emphysema the
41:48 surfactant kind of goes away and the
41:50 villa surface tension is you're not able
41:57 now the next factor that affects
41:59 pulmonary gas exchange is pulmonary compliance
42:00 compliance
42:01 this is the last physical factor that
42:03 influences the effectiveness of gastric exchange
42:04 exchange
42:06 all this is basically is the ability of
42:08 the lungs in the chest wall to stretch
42:09 and this is determined by a couple of
42:11 things one the degree of alveolar
42:13 surface tension
42:15 increasing surface tension resists the
42:17 ability of the velocity to inflate
42:19 the casing compliance so if your
42:22 available surface tension is increased
42:27 then you can't we can't fluff up anymore
42:29 distance ability elastic tissue gives
42:30 the lungs ability to stretch during
42:32 inflation increases compliance
42:34 the ability of the chest wall to move
42:36 increases compliance
42:37 so if the compliance decreases and the
42:40 lungs are ex less able to expand
42:42 you can't get enough air in so any of
42:44 these things will decrease compliance
42:52 so gas exchange is going to bring new air
42:52 air
42:55 into and remove oxygen poor air from the alveoli
42:56 alveoli
42:58 carbon dioxide is the waste product of
43:00 gas exchange and you want to get rid of it
43:01 it
43:03 so during pulmonary gas exchange oxygen
43:05 diffuses in from the air in the vela to
43:07 the blood and the pulmonary capillaries
43:09 carbon dioxide flows in the opposite
43:11 direction we're going to get rid of it
43:12 now the good thing about it is that they
43:14 actually don't compete for anything
43:16 they don't form bonds together and they
43:18 don't compete for space and hemoglobin so
43:19 so
43:21 they really don't even really notice
43:22 each other if they do they bump into
43:24 children and say uh i don't know you
43:27 keep on going so they don't there's no
43:29 problem with having oxygen or carbon dioxide
43:29 dioxide
43:31 in a given place because your body does
43:33 not they don't compete for anything
43:36 which is good now the the pulmonary gas
43:38 exchange involves exchanging the gases
43:40 between the alveoli in the blood
43:42 the tissue gas exchanges occurs at the
43:43 tissues in the body's systemic
43:45 capillaries in the body's cells
43:47 so you got two places where gas exchange
43:48 occurs one's in the lungs
43:52 the others in the tissues now what we
43:54 call pulmonary gastric exchange we call
43:56 that external respiration
43:58 this is the diffusion of gases between
43:59 alveoli and the blood
44:01 now again what's happening is that
44:03 oxygen goes in as carbon dioxide goes out
44:03 out
44:05 you can see the picture here so you
44:07 breathe in oxygen that's the red in the
44:08 picture here
44:11 and it's going to leave the alveolus and go
44:11 go
44:13 into the bloodstream carbon dioxide can
44:15 leave the bloodstream and go into the alveolus
44:16 alveolus
44:18 so going opposite directions so the pressure
44:23 is what's going to drive this so as
44:24 movement with all gases the pulmonary
44:25 gastric chain is driven by pressure changes
44:26 changes
44:28 you have a lower pressure on one side of
44:29 the membrane than you do on the other one
44:30 one
44:32 so the pressure gradients is created by
44:33 the difference in partial pressures of oxygen
44:34 oxygen
44:35 and carbon dioxide between the air and
44:36 the uv light and the blood and the
44:38 pulmonary capillaries
44:40 so if you look at the two graphs here
44:41 the one in red is the oxygen
44:44 the pressure in the alveolus is great
44:46 the pressure opponent capital is low how
44:49 does air flow from high pressure to low
44:50 pressure look at the pressure carbon dioxide
44:51 dioxide
44:54 it's actually lower in the uv less it is
44:55 in the prolonged capillary so again it's
44:56 going to go from high to low
45:00 now granted not a whole lot
45:03 lower now i want you to i want you to
45:04 answer this room it tells you here that
45:06 carbon dioxide's got a low pressure
45:07 gradient but a high solubility
45:11 um why do you think that it's more important
45:12 important
45:14 to have a high pressure of oxygen here
45:16 than it is for carbon dioxide think
45:17 about what oxygen does for you how
45:18 important it is
45:20 and tell me as your second disc question question
45:21 question
45:24 why do you think right here at the at
45:26 the alveolus you have a
45:29 higher pressure of oxygen than you do
45:36 now what can actually affect the
45:38 efficiency of pulmonary gas exchange well
45:38 well
45:41 one thing is the surface area of the
45:43 um restaurant membrane you have to have
45:45 a lot of surface area to be able to get
45:47 a lot of a lot of blood in there so
45:49 the the surface area is actually large
45:50 about a thousand square feet
45:51 whereas the quantity of blood
45:54 capillaries is about 100 milliliters
45:56 so any factor that reduces surface area
45:57 decreases efficiency pulmonary gas exchange
45:59 exchange
46:00 the thickness of the respiratory membrane
46:02 membrane
46:04 which is the distance to the mass that
46:06 uh gas must
46:09 diffuse now what can change that well
46:11 normally it's thin but anything that
46:12 increases the thickness like inflammation
46:14 inflammation
46:16 will diminish gas exchange especially if
46:17 you've got
46:20 some kind of water in there where would
46:21 the water come from
46:24 well the water would come from bacteria
46:25 in your lungs from pneumonia that's why
46:28 pneumonia kills you pneumonia diminishes
46:30 your capacity to get air into your lungs
46:32 when you've got pneumonia in your lungs
46:34 you're blocking it and if you block it
46:37 you die you know i knew a woman
46:39 um gosh it was a long time ago now she
46:40 was a friend of mine
46:43 in college that died of pneumonia she's
46:44 only 29.
46:47 she died of pneumonia because
46:51 she smoked you know heavily and wasn't
46:52 able to fight off bacteria
46:54 and died of pneumonia at 29 years old so
46:56 it was
46:59 terrible now ventilation profusion matching
47:00 matching
47:02 or coupling meaning that the degree of
47:04 match between the amount of air reaching
47:05 the vehiline amount of blood flow
47:08 that's important because that needs to match
47:09 match
47:10 the changes in the vehicle ventilation
47:12 lead to changes in perfusion the blood
47:13 flow is directed to the areas with most oxygen
47:14 oxygen
47:16 if you change it then air flow is
47:19 distributed to areas with most flow
47:21 the combination of these ensures that
47:22 ventilation and perfusion match or at least
47:23 least
47:25 are a couple closely to each other so
47:26 what that means
47:28 and let me just sum that up for you that
47:29 means that
47:32 your blood is going to go
47:36 to an area that's got the most oxygen
47:39 so it can pick it up so
47:41 you'll have more in there so you don't
47:43 want to you don't want to put blood into
47:44 a tissue when there's no oxygen in that blood
47:45 blood
47:46 you want to make sure that all the all
47:48 the oxygen is is carried
47:51 correctly that's what that means and tissue
47:52 tissue
47:53 gas exchange is called internal
47:55 respiration what's happening here again
47:57 is that the partial pressures of carbon dioxide
47:58 dioxide
48:01 and oxygen are using that gradient to
48:04 diffuse in and out of the tissues
48:07 so the cells use oxygen constantly for
48:08 slow respiration so the
48:10 the partial pressure of oxygen and
48:12 tissue is low while the pressure
48:14 pressure instead of capillaries is high
48:17 and again what that does is to allow the
48:18 oxygen to go
48:20 into the tissues again from high to low
48:22 pressure so that's that's the way that
48:23 you get you get oxygen into your tissues
48:25 is that the oxygen pressure is higher in
48:26 the capillaries
48:27 than it is in the tissue cells that will
48:29 diffuse easy
48:31 now they also produce a lot of carbon
48:32 dioxide which is a waste product
48:34 partial pressure is relatively high or
48:36 it's low in systemic capillaries again
48:36 this is going to
48:40 favor the diffusion of carbon dioxide
48:42 into the tissues from the tissue from
48:44 the tissues to the capillaries
48:45 that's how you're able to push carbon
48:48 dioxide out of your tissues into the
48:54 now again there are certain factors that
48:55 will that will affect tissue gas
48:56 exchange as well
48:59 one is the surface variable available
48:59 for that
49:02 uh if it large enough to allow gastric
49:03 chains efficiently
49:06 the distance again if you have a less
49:08 distance it results in more deficient
49:09 gas exchange
49:12 some of our uh organs are actually so
49:14 far away from
49:16 tissue gas exchange they don't get very
49:17 efficient gas exchange that includes
49:20 like your skin things like that
49:22 also the perfusion the tissue the more
49:23 blood you have in it the more efficient gas
49:23 gas
49:25 exchange you have the less blood you
49:26 have in it the less
49:30 so example for example cartilage
49:32 cartilage does not have very much blood
49:33 supply therefore
49:35 cartilage does not have good profusion
49:37 therefore it takes a long time for a
49:39 tear and cartilage to heal
49:40 because you don't have any blood in
49:49 now how is how are gases transported in
49:49 our blood
49:51 well in order for pulmonary and tissue
49:52 gas exchange to occur
49:54 oxygen and carbon dioxide must undergo
49:56 chemical reactions that allow for these
49:57 poorly soluble gases to be
50:00 transported safely what does that mean
50:02 well that means that you have to find a
50:02 way to
50:04 safely transport your gases in the blood
50:07 so they don't harm you
50:10 oxygen is transported mostly bound to hemoglobin
50:12 hemoglobin
50:14 hemoglobin are proteins that have oxygen
50:16 bounds and they're bound to the iron of
50:17 the protein
50:20 and about 1.5 percent is dissolved in
50:21 blood plasma
50:23 but oxygen is very is not soluble it's
50:24 very poorly soluble
50:27 so it doesn't dissolve easily in blood
50:28 plasma so
50:30 majority of it is stuck to hemoglobin
50:31 and it's red
50:33 so my blood is red that's why mars is
50:35 red that's why breast is red
50:37 anytime iron hits oxygen it's red so
50:39 that's why you have that color
50:42 carbon dioxide there are three ways the
50:43 carbon dioxide can be
50:46 can be transported including as a
50:49 bicarbonate ion
50:52 now oxygen is transported in the blood
50:54 bound to hemoglobin hemoglobin
50:55 is a protein a very large protein that's
50:57 found in red blood cells
50:59 basically all they are just little bags
51:02 of little bags of hemoglobin
51:04 each one's got a heme group that's got
51:06 an iron atom each one of those can bind
51:08 to a molecule of oxygen each one's got
51:10 four of them so
51:13 each hemoglobin molecule can bind to
51:15 four oxygen molecules which allows you to
51:16 to
51:18 actually take a lot of oxygen through
51:20 the bloodstream to the different cells
51:22 in your body
51:26 the oxygen and iron together it's red
51:28 so the hemoglobin pigment turns the blood
51:29 blood red
51:34 oxygen is transported through the
51:36 bloodstream down the hemoglobin now
51:37 what's happening
51:39 the partial pressure of oxygen is
51:41 pushing the oxygen through
51:44 the uh tissue wall into the bloodstream
51:45 and what's happening
51:47 is that as the blood cells are going by
51:49 it's popping onto it it's hitting it
51:50 so the oxygen is binding to the
51:52 hemoglobin in which it will go
51:56 into the tissues so it travels all the
51:56 way through
51:59 and it goes to the tissues and when it
52:00 gets there
52:03 the pressure is going to change it's
52:04 going to be a higher pressure
52:06 it's going to go to lower pressure so
52:08 the pressure of oxygen is higher in the
52:10 capillary is going to diffuse off into
52:11 the tissue cells
52:13 so tissue cells have lower oxygen than
52:15 the capillaries it's going to
52:16 go the opposite direction so it's going
52:18 to pop on in the
52:20 in the alveolus to the blood to the
52:22 blood cells that's going to pop off the
52:23 blood cells
52:30 oxygen bound to hemoglobin we call that
52:31 the percent saturation
52:34 the hemoglobin saturation depends on two
52:35 things one of course is the pressure of
52:37 oxygen in both lungs and tissues if you
52:39 have a high pressure it's going to
52:42 bind to it easier or the affinity the tightness
52:42 tightness
52:44 the bond strength which hemoglobin binds
52:46 to oxygen you can
52:48 change that you can change the affinity
52:49 of hemoglobin for oxygen
52:51 one is by increasing temperature that
52:52 can change it
52:55 also increase increasing hydrogen ion
52:57 concentration that increases the ph of blood
52:57 blood
52:59 so that can also affect it so you don't
53:01 want to have a blood ph it's above or
53:03 below 7.35 7.45
53:06 if you have that then the hemoglobin's
53:07 affinity for oxygen can decrease and it
53:09 can kill you
53:12 and as tissue produce atp the partial
53:14 pressure of carbon dioxide increases
53:15 all of that can actually affect the
53:18 hemoglobin d for oxygen and result in
53:21 unloading oxygen into tissues
53:24 now carbon dioxide is transported
53:26 through the blood in different ways this is
53:26 is
53:27 completely different than oxygen now
53:29 good the good thing about this
53:33 is that it does not compete with oxygen
53:35 part of carbon dioxide about seven ten
53:37 percent of total carbon dioxide
53:39 is produced specimen metabolism is
53:40 transported dissolved in blood plasma
53:42 which is way more than oxygen oxygen's
53:43 about one percent
53:46 it's also bound to hemoglobin about 20
53:48 percent is total
53:50 bounded hemoglobin uh it doesn't bind to the
53:51 the
53:53 the heme group though it binds to the
53:55 peptide chains we call this carbomedia hemoglobin
53:56 hemoglobin
53:58 so some of it does stick to the
53:59 hemoglobin but not the same part as oxygen
54:00 oxygen
54:02 some of it's in the blood plasma now why
54:03 do you think
54:05 that the majority of it is not in blood
54:06 plasma well
54:08 think about when you have like a
54:11 coca-cola and you shake it up
54:12 what would happen if your blood did that
54:13 you had carbon dioxide well then it
54:14 would poof
54:16 you know it would it fills up we don't
54:17 do that we don't want to do that so
54:19 that's how we're able to
54:23 to uh dissolve it in plasma
54:24 now the bicarbonate ion is how most of
54:26 it's going to going to uh
54:28 effect it's going to be transported in
54:30 the blood in the form of bicarbonate ion
54:32 which is not the form of co2
54:34 and that's very important in maintaining
54:38 your ph homeostasis in your blood
54:41 how this works is that when carbon
54:44 dioxide diffuses into your blood cells
54:46 it encounters an enzyme called carbonic
54:48 anhydrase and what that does
54:51 is to catalyze this reaction carbon dioxide
54:52 dioxide
54:54 in water is going to form what we call
54:55 carbonic acid
54:57 carbonic acid then is quickly converted
55:00 into bicarbonate ion and a hydrogen ion
55:04 now here's the thing hydrogen ion by
55:06 itself is like an unruly teenager
55:08 it does not like to be told what to do
55:10 does not like to be controlled
55:12 so what you've got to do you have to be
55:14 able to
55:16 make sure that that does not get out of
55:18 hand you got to control it
55:20 so what you have to do is that the hydrogen
55:21 hydrogen
55:24 bounds to hemoglobin if you didn't do
55:26 that then it would cause your blood ph
55:27 to become very acidic it would lower it and
55:28 and
55:31 it could kill you so hemoglobin says
55:31 real change
55:33 i'm gonna smack you and it takes the
55:35 hydrogen ion says hey
55:37 hold on to that well because you have a
55:39 hydrogen ion hanging out there bound to
55:41 hemoglobin you also have a negatively
55:42 charged bicarbonate ion hanging out there
55:43 there
55:46 well when you have a negatively charged
55:48 ion that leaves the
55:49 the blood cell and goes out into the
55:51 blood plasma that creates
55:56 a balance imbalance a charge imbalance
55:59 so what happens is that chloride ions
56:00 that are present in your bloodstream
56:05 are going to shift into the blood cells
56:07 to balance out the charges we call that
56:08 a chloride shift
56:13 a change in charge like that of your
56:15 cells and expect it to be okay
56:17 because you've got to balance out the
56:18 charge otherwise you have too much
56:20 father too much negative in any place
56:26 now carbon dioxide travels through the
56:27 bloodstream mostly
56:29 again mostly in the bicarbonate ion well
56:31 what happens when it gets up to
56:34 the alveoli the carbonic acid is
56:36 reformed the hemoglobin
56:38 lets go that unruly teenager that
56:39 hydrogen ion
56:43 and it's going to reform carbonic acid
56:47 with carbonic anhydrase that's going to
56:49 then put it back into carbon dioxide and
56:50 water then it can just spit it out
56:52 so carbon dioxide that point is free to
56:54 go so
56:56 it leaves your cells as carbon dioxide
56:58 it travels in your blood is bicarbonate
57:00 then it goes back into your alveolus as
57:02 carbon dioxide where you exhale it
57:05 so you reform it isn't that cool
57:14 now how do we change that
57:16 well changes in partial pressure carbon
57:18 dioxide hydrogen ions and partial
57:19 portion of oxygen are all stimulants for ventilation
57:20 ventilation
57:22 if you change any of these things your
57:23 amount of
57:25 is going to change so the major
57:26 determinant the one that's most
57:28 important is the pressure of carbon dioxide
57:28 dioxide
57:30 i know you guys think that oh well we
57:32 breathe in because we need oxygen for
57:33 our cells
57:35 really what you're actually trying to do
57:38 is not have too much carbon dioxide
57:42 so you got to breathe in to to actually
57:45 to control that so the the
57:47 carbonic acid is determined for hydrogen
57:49 ions and therefore blood ph so the
57:51 pressure carbon dioxide is the major
57:52 determinant for the blood ph
57:55 so that's really what controls your it's
57:56 the carbon dioxide not the amount of
57:58 oxygen you need it's
58:01 that's not really what it is um
58:02 so a change in normal pattern
58:04 ventilation can have a dramatic impact
58:04 on blood
58:06 concentration of hydrogen ions the more
58:08 you breathe in
58:10 the higher oxygen content you have lower
58:12 carbon dioxide you have
58:16 lower ph so if you're hyperventilating
58:18 that's bad for you so they tell you to
58:19 breathe into a paper bag
58:20 so you won't get too much oxygen in
58:22 there because if you do that you can you can
58:23 can
58:29 so again hyperventilation increases the
58:31 amount of carbon dioxide expired from
58:31 the lungs
58:33 so what that does is cause the ph of
58:35 blood to rise it causes because
58:37 become more basic and that leads to
58:39 alkalosis which is bad for you
58:41 if your blood ph increases because of
58:42 carbon dioxide
58:46 increasing then you can have a blood ph
58:47 that can
58:50 harm you hypoventilation
58:52 meaning you decrease the amount of
58:54 breathing causes more carbonic acid to
58:56 form and less
58:58 carbon dioxide which can lead to what we
59:00 call hypoxemia
59:03 so the oxygen levels drop that causes acidosis
59:04 acidosis
59:06 your blood becomes too acidic both of
59:07 these are really bad for you because
59:08 what happens
59:09 is when you've got an increase or
59:11 decrease in blood ph
59:13 your blood starts reacting with stuff
59:14 that it shouldn't be reacting with so
59:16 the the blood does not do what it's
59:18 supposed to do the affinity for
59:19 hemoglobin is messed up and then you
59:21 can't breathe and then you die
59:24 so acidosis and alkalosis caused by hyper
59:25 hyper
59:27 hypoventilation can kill you so when
59:28 somebody's hyperventilating
59:31 they put a paper bag so they don't so any any
59:32 any any
59:34 any they won't get too much oxygen you
59:35 know so that's what they're doing with that
59:40 the way to remember kind of what's going
59:41 on hyper means
59:44 above hyperventilation means you your ph increases
59:44 increases
59:47 hypo means below your ph decreases so if
59:49 you hyperventilate your blood ph
59:52 rises if you hypoventilate your blood ph decreases
59:54 decreases
59:55 now the lower the ph the higher the
59:57 hydrogen ion concentration and vice
59:59 versa so that's what that's telling you
60:01 and again having too much hydrogen ion in your body
60:02 in your body is bad
60:10 now unfortunately unlike our hearts which we talked about already in amp2 we
60:14 which we talked about already in amp2 we we actually have to control the group of
60:17 we actually have to control the group of uh breathing with our um
60:22 uh breathing with our um our brain so you have what we call
60:24 our brain so you have what we call euphenia which is normal breathing
60:25 euphenia which is normal breathing breathing occurs without conscious
60:27 breathing occurs without conscious thought of control you
60:29 thought of control you do it even though you don't know you're
60:30 do it even though you don't know you're doing it you have to do it no matter
60:32 doing it you have to do it no matter what
60:33 what but your brain does control it it's
60:35 but your brain does control it it's controlled by
60:36 controlled by neurons down the brain stem the pontine
60:38 neurons down the brain stem the pontine respiratory group which you've got in
60:40 respiratory group which you've got in here what we call a respiratory rhythm
60:41 here what we call a respiratory rhythm generator
60:42 generator this creates basic rhythm for breathing
60:45 this creates basic rhythm for breathing in addition to that you got other things
60:49 in addition to that you got other things negative feedback loops and stretch
60:50 negative feedback loops and stretch receptors in the lungs ensure oxygen
60:52 receptors in the lungs ensure oxygen intake
60:53 intake and carbon dioxide elimination match
60:54 and carbon dioxide elimination match metabolic requirements
60:56 metabolic requirements what does that mean that means that uh
60:59 what does that mean that means that uh you are breathing in oxygen breathing
61:02 you are breathing in oxygen breathing out carbon dioxide
61:03 out carbon dioxide and if you need more of that that's
61:05 and if you need more of that that's going to tell you
61:06 going to tell you breathe harder you know sometimes you'll
61:08 breathe harder you know sometimes you'll do that sometimes you'll sit there you
61:09 do that sometimes you'll sit there you go
61:10 go like that that's because your body says
61:12 like that that's because your body says all right i need some more you're not
61:13 all right i need some more you're not giving me enough
61:14 giving me enough you're not breathing hard enough
61:17 you're not breathing hard enough now again there is some voluntary
61:19 now again there is some voluntary control or ventilation supplied by
61:21 control or ventilation supplied by cerebral cortex
61:22 cerebral cortex which can override or bypass respiratory
61:24 which can override or bypass respiratory centers what that means
61:25 centers what that means is you actually can make yourself
61:28 is you actually can make yourself breathe in more if you choose to do that
61:31 breathe in more if you choose to do that you can also make yourself stop
61:33 you can also make yourself stop breathing as
61:33 breathing as you know you can hold your breath for a
61:35 you know you can hold your breath for a little while and then eventually that
61:36 little while and then eventually that will pass over and you will
61:38 will pass over and you will have to breathe again so it's like when
61:39 have to breathe again so it's like when you're when your little boy or girl says
61:41 you're when your little boy or girl says i'm going to kill myself you don't do
61:43 i'm going to kill myself you don't do what i want i'm going to stop breathing
61:44 what i want i'm going to stop breathing good luck with that
61:45 good luck with that all right uh it ain't going to work
61:47 all right uh it ain't going to work they're going to if
61:48 they're going to if they do pass out they're going to come
61:50 they do pass out they're going to come back up you know in a moment so you
61:52 back up you know in a moment so you cannot do that
61:52 cannot do that your brain will override that so that's
61:55 your brain will override that so that's not a way to
61:56 not a way to to commit suicide it ain't going to work
61:57 to commit suicide it ain't going to work that way
62:04 now the controls again that we use for this
62:05 this cerebral cortex is voluntary control
62:06 cerebral cortex is voluntary control they also have some changes in arterial
62:09 they also have some changes in arterial concentration of hydrogen ions changes
62:12 concentration of hydrogen ions changes in
62:13 in pressure of carbon dioxide and changes
62:16 pressure of carbon dioxide and changes in pressure of oxygen
62:18 in pressure of oxygen you have that picked up by receptors
62:20 you have that picked up by receptors chemoreceptors central receptors
62:21 chemoreceptors central receptors peripheral scepters
62:22 peripheral scepters and they tell your the ponds what you
62:25 and they tell your the ponds what you see here
62:25 see here you see that the pontine respiratory
62:27 you see that the pontine respiratory groups which you look at in the picture
62:28 groups which you look at in the picture here the brain stem
62:29 here the brain stem and that's going to carry out a message
62:31 and that's going to carry out a message that tells your breathing to increase or
62:33 that tells your breathing to increase or decrease
62:35 decrease alright so i would like you to tell me
62:37 alright so i would like you to tell me what you thought was most interesting
62:38 what you thought was most interesting about this chapter as your third and
62:39 about this chapter as your third and final discussion
62:41 final discussion question