We have spent a bit of time discussing the heart, touching on anatomy, function, and investigative tests. I think it's time to move on to something else before we all get bored.
In that spirit, what better place to continue our blog than the heart's closest friend and neighbour, the lungs. Those big bags of air that take up most of the space in our chest. They may seem boring, but could you imagine living without them?
Exit Stage Right...and Left
Let's start with a bit of anatomy. The "respiratory tract" actually starts in the same place the gastrointestinal (GI) tract does - the mouth, and then splits at the larynx (just below where you can see if you open your mouth and look in the mirror at that hangy-ball thing). The GI tract continues on as the esophagus, whereas the airway tube passes through the vocal cords and continues on as the trachea (TRAY-key-ahhhh). Then what happens? Well, there is a right and left lung, so the trachea eventually divides into two sides and continues on into each of these sides. As a matter of fact, the airway tract will keep dividing as it moves along, over and over again, with each successive tube getting smaller and smaller until they can't really get any smaller (Chandler: "Could these tubes BE any smaller??"). This is the terminal point of the respiratory tract, and these little pouches at the end of the progressive branching of tubes are called ALVEOLI (or alveolus as the singular version).
How many of these are there? Well, about 700 million of them in each of us (check it out on Wikipedia - I just did), and each one of them is about the width of a human hair. Why do we need so many?? Well, that relates to the function of the lungs, and what they are actually stuck in our body to do - gas exchange.
Having so many of these plunked into each of the lungs provides a HUGE amount of surface area for oxygen to be delivered to the blood, and carbon dioxide to exit. In fact, it creates about 100 square metres (or 1000 square feet - again check it on Wiki) of surface area, which is way bigger than my first apartment.
Let's talk a bit about all of this in a different way. Time for a stage dive...
The Windy Park
Let's go to Chicago. And let's go in August. Every year, this great city is infused with thousands of young revellers for Lollapalooza, a multi-day music festival in Grant Park, featuring dozens of acts on multiple stages. In fact, here is a map of the park during the festival, and it provides a perfect framework for the lungs.
In that spirit, what better place to continue our blog than the heart's closest friend and neighbour, the lungs. Those big bags of air that take up most of the space in our chest. They may seem boring, but could you imagine living without them?
Exit Stage Right...and Left
Let's start with a bit of anatomy. The "respiratory tract" actually starts in the same place the gastrointestinal (GI) tract does - the mouth, and then splits at the larynx (just below where you can see if you open your mouth and look in the mirror at that hangy-ball thing). The GI tract continues on as the esophagus, whereas the airway tube passes through the vocal cords and continues on as the trachea (TRAY-key-ahhhh). Then what happens? Well, there is a right and left lung, so the trachea eventually divides into two sides and continues on into each of these sides. As a matter of fact, the airway tract will keep dividing as it moves along, over and over again, with each successive tube getting smaller and smaller until they can't really get any smaller (Chandler: "Could these tubes BE any smaller??"). This is the terminal point of the respiratory tract, and these little pouches at the end of the progressive branching of tubes are called ALVEOLI (or alveolus as the singular version).
How many of these are there? Well, about 700 million of them in each of us (check it out on Wikipedia - I just did), and each one of them is about the width of a human hair. Why do we need so many?? Well, that relates to the function of the lungs, and what they are actually stuck in our body to do - gas exchange.
Having so many of these plunked into each of the lungs provides a HUGE amount of surface area for oxygen to be delivered to the blood, and carbon dioxide to exit. In fact, it creates about 100 square metres (or 1000 square feet - again check it on Wiki) of surface area, which is way bigger than my first apartment.
Let's talk a bit about all of this in a different way. Time for a stage dive...
The Windy Park
Let's go to Chicago. And let's go in August. Every year, this great city is infused with thousands of young revellers for Lollapalooza, a multi-day music festival in Grant Park, featuring dozens of acts on multiple stages. In fact, here is a map of the park during the festival, and it provides a perfect framework for the lungs.
OK, so the lungs don't exactly look like Lollapalooza, but let's try to imagine it anyway. Here goes...
Main entrance - see that big red arch on Columbus Drive? That's our trachea. And for our purposes, the only way in or out of the concert venue.
Southpalooza - this is everything to the right of Buckingham Fountain, and thus will be our right lung.
Northpalooza - similarly to above, this will be our left lung.
Now, we have an endless supply of concert ticket holders, and each of these people will represent a unit of atmospheric air. Air contains oxygen, which is the thing we need to survive. You want to see the concert? Our ticket holders will need a badge around their necks, which will represent oxygen.
We also have a huge wall of security guards, placed around the outer border of the park. These are the muscle - literally. They represent the collection of muscles that surround the lungs, from the chest wall and rib muscles to the diaphragm separating the chest cavity from the abdomen.
Our Lolla is a bit different than the real one. Our ticket holders are only allowed in to see one song and then have to leave, and all of the stages are running at the same time. Bad for them, but good for us.
Never Ending Mosh Pit
Let's start. Performers are set, stages are full, and now we need an audience. The wall of security retreats back to the perimeter, allowing a huge influx of people from the main entrance of the park. Everyone wants to get as close to the stages as possible, and so they pack into the park, shoulder to shoulder, filling up every piece of real estate they can find waiting for their one and only song to be played. It's going to cost them their oxygen badge, so they all hand these to the band they are listening to (on whichever stage they are closest to), and in return, they get a signed photo of their idols.
Main entrance - see that big red arch on Columbus Drive? That's our trachea. And for our purposes, the only way in or out of the concert venue.
Southpalooza - this is everything to the right of Buckingham Fountain, and thus will be our right lung.
Northpalooza - similarly to above, this will be our left lung.
Now, we have an endless supply of concert ticket holders, and each of these people will represent a unit of atmospheric air. Air contains oxygen, which is the thing we need to survive. You want to see the concert? Our ticket holders will need a badge around their necks, which will represent oxygen.
We also have a huge wall of security guards, placed around the outer border of the park. These are the muscle - literally. They represent the collection of muscles that surround the lungs, from the chest wall and rib muscles to the diaphragm separating the chest cavity from the abdomen.
Our Lolla is a bit different than the real one. Our ticket holders are only allowed in to see one song and then have to leave, and all of the stages are running at the same time. Bad for them, but good for us.
Never Ending Mosh Pit
Let's start. Performers are set, stages are full, and now we need an audience. The wall of security retreats back to the perimeter, allowing a huge influx of people from the main entrance of the park. Everyone wants to get as close to the stages as possible, and so they pack into the park, shoulder to shoulder, filling up every piece of real estate they can find waiting for their one and only song to be played. It's going to cost them their oxygen badge, so they all hand these to the band they are listening to (on whichever stage they are closest to), and in return, they get a signed photo of their idols.
Once the exchange of badges for photos has taken place, and the single song has been played, it's time for the audience to leave the park. We need some security force here. Guards from the perimeter start to push and squeeze and force all of the concert-goers back out through the main entrance in order to prepare for the next influx of badge-toting fans. Now repeat with the next swash of hipsters outside the gate, just waiting to have the chance to get their signed photo.
This is, in essence, exactly how the lungs function. Air enters the lungs because a vacuum is created when the chest wall expands and the diaphragm lowers. It makes the lung space bigger, and air pressure will then be lower than what is outside our bodies. Air pressure has a natural tendency to want to be equal, and in order to equate the lower inner air pressure with the higher outer pressure, air moves in to the lungs to take up all available space. This is like our concert. Security guards move out of the way to the periphery, and music fans will naturally want to move from an area of high density (outside the main gate) to the area of lower density (inside the park). They will move to all nooks and spaces of the park in order to get as close to the multiple stages as possible - who wouldn't want a signed photo?? These multiple stages, and the exchange of badges (oxygen) for photos (carbon dioxide), represents our alveoli (little air sacs) where gas exchange takes place in the lungs. Oxygen moves from the alveoli into the bloodstream, because each and every alveoli is surrounded by a bunch of tiny vessels called capillaries. These capillaries are also carrying waste from the body in the form of carbon dioxide, something that we would like to get rid of. So, an exchange takes place. Oxygen goes into the blood, and carbon dioxide goes out. Now, to be fair, our Lollapalooza would have to contain about 700 million stages, so that each and every fan would be able to get a front row spot to a band and be able to make the badge/photo exchange with them, but you get the picture. Air is then forced out of the lungs because of the muscles again. The diaphragm moves back up towards the chest and the ribs and chest wall begin to squeeze the lungs from the outside, creating increased pressure within the lungs (compared to the outside) and thus air moves back out of the main entrance (trachea).
It seems relatively simple. Air moves in. Air moves out. And yes, it is pretty simple. But what I want you to get is that it's not the air that we are interested in. It's what is in the air that is important. I would rather you think of the lungs as "oxygen moves in, and carbon dioxide moves out". This is only slightly different than the first version, but is vastly different in understanding the function of the lungs. Big bags of air? Not so much.....
Success? I hope this provides some better understanding of the lungs, and how/why they do what they do. Stay tuned for my next post which will talk more about lungs and maybe.......disease??
This is, in essence, exactly how the lungs function. Air enters the lungs because a vacuum is created when the chest wall expands and the diaphragm lowers. It makes the lung space bigger, and air pressure will then be lower than what is outside our bodies. Air pressure has a natural tendency to want to be equal, and in order to equate the lower inner air pressure with the higher outer pressure, air moves in to the lungs to take up all available space. This is like our concert. Security guards move out of the way to the periphery, and music fans will naturally want to move from an area of high density (outside the main gate) to the area of lower density (inside the park). They will move to all nooks and spaces of the park in order to get as close to the multiple stages as possible - who wouldn't want a signed photo?? These multiple stages, and the exchange of badges (oxygen) for photos (carbon dioxide), represents our alveoli (little air sacs) where gas exchange takes place in the lungs. Oxygen moves from the alveoli into the bloodstream, because each and every alveoli is surrounded by a bunch of tiny vessels called capillaries. These capillaries are also carrying waste from the body in the form of carbon dioxide, something that we would like to get rid of. So, an exchange takes place. Oxygen goes into the blood, and carbon dioxide goes out. Now, to be fair, our Lollapalooza would have to contain about 700 million stages, so that each and every fan would be able to get a front row spot to a band and be able to make the badge/photo exchange with them, but you get the picture. Air is then forced out of the lungs because of the muscles again. The diaphragm moves back up towards the chest and the ribs and chest wall begin to squeeze the lungs from the outside, creating increased pressure within the lungs (compared to the outside) and thus air moves back out of the main entrance (trachea).
It seems relatively simple. Air moves in. Air moves out. And yes, it is pretty simple. But what I want you to get is that it's not the air that we are interested in. It's what is in the air that is important. I would rather you think of the lungs as "oxygen moves in, and carbon dioxide moves out". This is only slightly different than the first version, but is vastly different in understanding the function of the lungs. Big bags of air? Not so much.....
Success? I hope this provides some better understanding of the lungs, and how/why they do what they do. Stay tuned for my next post which will talk more about lungs and maybe.......disease??