15 Crazy Things You Didn't About An Unborn Baby's Lungs

It shouldn’t come as any surprise that some pretty amazing things happen in the womb while the fetus develops. After all, this little cluster of cells comes together and relatively quickly (9 months seems like a century on the outside, but really…) forms into human life ready to slide into the real world. That is something spectacular.

From a fully functioning brain to limbs that are moving around, by the end of that 9 month period, the fetus sure has come a long way. The baby has shed his fur coat (literally) and learnt how to see underwater (also literally). Even just two months prior to coming out of the womb, the fetus looked more alien that it did baby. Therefore, little baby sure does deserve some acknowledgement for getting his act together over the past 9 months.

Alongside the rest of the amazing development, you’ve got to give a shout out to the lungs. These are a vital organ, and the way that they develop in utero is pretty remarkable. Again, these start off as a cluster of cells and eventually work out to become the fundamentals of breathing. It is rather impressive that the lungs are ready for action as soon as baby is introduced to the lights.

The lungs literally jump into gear and inhale and exhale air as though a switch has a flicked. So how do they get to this point? What exactly happens in the womb to ensure the lungs are fully fledged organs for baby to survive on the outside? Find out some fun lung facts right here!

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15 There Are Five Stages To Lung Development

When the lungs develop, they do it in style. They want recognition for every bit of development that takes place. There is a stage for each of it. And we’ve got to hand it to the lungs, they do deserve this.

Starting at about 4 weeks of gestation, the fetus starts to develop lungs. At this point, the cells are still pretty unrecognisable and not specialised, but the beginning stages of lung development are slowly happening. They’re allowed to take their time, after all.

So the five important stages of lung development happen from gestation to early childhood. They include:

  • The embryonic stage during weeks 4 and 5
  • The pseudo-glandular phase where the lungs sit until about week 17
  • The canalicular stage that lasts until around week 25
  • The saccular phase which ends at week 36
  • The alveolar phase is the final stage that lasts into early childhood

14 Left And Right Lungs Form In Embryonic Stage

At around 4 or 5 weeks from the point of conception, the embryonic phase of lung development occurs. Some pretty cool things start happening at this point considering a whole bunch of cells are working together to form a fetus right now. At this stage, the cell ball of future fetus and baby isn’t particularly specialised, but the cells know what needs to happen along the way. Thanks, biology!

As early on as this, two teeny tiny buds branch off from the rest of the cells. These rebels actually form what will become the right lung and the left lung. What’s more, the larynx and the trachea will also start gathering their cells and forming during this stage.

That’s some pretty amazing stuff happening right there. The lungs are switched on to their development almost from day one. They’ve got their target goal well and truly in sight. Go lung cells, go!

13 Blood Vessels Happen In Pseudo-Glandular Stage

From the embryonic stage, the lung cells are more or less just hanging out for a while. However, things start to get exciting at week 17. This is when they enter the pseudo-glandular stage. At this point, those cells that worked hard earlier on to branch off to the left and right lung keep up their action. They start to break off into smaller and more numerous units.

During this time, the lung cell buds become independent respiratory units. Considering they’re going to have to be responsible for the whole breathing thing later on, it’s a good thing they’re acting now!

Also during the pseudo-glandular phase, the capillary vessels that are going to surround and support the lungs start forming. These are important vessels that bring blood to the lungs so that they can keep pumping oxygen. They’re kicking into gear at this stage too so that everything will be fully functioning later on.

12 The Canalicular Phase Makes A Barrier

From week 17 after the pseudo-glandular phase has done its thing, the canalicular phase takes over and makes progress until around week 25. During here, a barrier is being formed in some pretty important places. This barrier is basically between air and blood. Oxygen needs to enter the blood through respiratory capillaries, but someone has to monitor how much is getting through. This is why this barrier is being created.

Another important thing that this barrier does is allow blood to enter the capillaries, but also letting carbon dioxide flow out of the respiratory capillaries so that the lungs can inhale and exhale.

Also, throughout the canalicular phase, the lung tissue starts changing. This is really cool because it means the air transport tissue is starting to become a thing. This stuff is important since it literally transports air through the lungs. Throughout this phase it starts to stands out more against gas-exchange tissue. Yeah, there’s a difference!

11 Soapy Stuff Happens In The Saccular Phase

After all that canicular stuff has happened, the saccular phase takes over until week 36. So as the name of this one suggests, some stuff is happening around the lung sacs. A thing called surfactant starts being produced in the lungs.

This substance is really soapy-like and it helps the delicate lung tissue from sticking to itself. This is important as otherwise it risks ripping during exhalation or if the lungs become compressed. Also, surfactant is going to help during delivery as it allows the lungs to drain away the amniotic fluid properly and fill up with air on the outside.

As gross as it sounds that the lungs are basically getting a soapy covering, it obviously has its merits. Lungs with surfactant are like deflated balloons and no one wants those inside their body. Surfactant is really kicking goals in the lungs, and it’s going to help baby kick literal goals on the outside with all that awesome inhalation and exhalation.

10 The Alveolar Phase Is All About Expansion

This final phase of lung development starts in the womb but stays around much longer. Obviously babies keep on growing after they’ve popped out into the real world. There’s still so much development that takes place in the infant and early childhood years, and the lungs are part of this action.

During the alveolar phase, the bronchioles and air sacs in the lungs start expanding. The tissues that carry gas around the lungs also gets bigger and these expand, meaning the lungs can become more and more efficient for carrying air around.

As the lungs get bigger and more used to their role in the world, your little baby gets better and better at breathing. It is easy to forget how exhausting just the simple task of breathing is in those first few months, hence why babies need to sleep so much. But just remember, those lungs are working very hard to keep growing and developing for this purpose.

9 Baby’s Breathe Rhythmically In The Womb

While the fetus doesn’t technically breathe in the womb, the breathing actions do create rhythmic pulses. Basically, the mom breathes for the fetus (as well as feeding it, drinking water for it, and peeing endless times a day for it). But really, mom’s oxygen is passed through to baby via the umbilical cord.

However, at around 9 weeks of pregnancy, the fetus starts to make breathing actions. These are really just pulses and actions, where not much is happening. Further along the pregnancy process, these breathing actions become more intense. This is where baby inhales and exhales the amniotic fluid as the lungs start developing. At 9 weeks, you won’t be able to feel much, but further along with pregnancy, some rhythmic pulses can be felt with the baby’s breathing practice.

Usually this rhythmic breathing can only be seen or heard on an ultrasound, but some moms do claim to have felt it or heard it themselves. Listen closely!

8 Lung Development Is Rapid After Birth

Pretty much everything that happens as soon as the baby is out of the womb happens rapidly. From cutting the umbilical cord to getting washed to driving home...and then suddenly the newborn is 18 years old and no mom can figure out where the time has gone!

Lung development is something that happens quickly after birth, and it kind of needs to. In the first 6 months of life, those lungs are working overtime to support your baby’s growth and important ability to breath in and exhale as much air as they need.

The first 6 months is when air sacs develop super fast. They start to slow down after 6 months, but the lung volume continues to increase during the first 2 years at quite a rapid pace. By the time your child is 3, their lungs are fully formed and just about stopped growing, they resemble a miniature version of adult lungs.

7 The Baby Practices Inhaling Amniotic Fluid

No one can ever accuse a fetus of doing no work. In fact, while they’re hanging out in the womb, those little troopers are doing a lot of practise to get ready for the real world. Considering they don’t know what is awaiting them on the other side of that birthing canal, they’re doing a good job.

Practising breathing is one of the things that the fetus will do in utero. Even though the lungs aren’t fully formed, at around week 32 the baby starts giving those things a go. Since the baby is floating in a sac of amniotic fluid, they aren’t exactly breathing in real air. But the lungs are still getting a go at the inhale and exhale motions.

So as baby is chilling out the amniotic fluid, every so often he’ll breath some of it in. The lungs are like ‘hey, this is cool, let’s try exhale now’, and the motions are put into place. This is really important that the lungs can do this movement so that once air is in the picture, they’ll be all over it.

6 Hormones Empty The Lungs After Birth

One word that every pregnant mom is going to get familiar with is hormones. From hormones to changing to hormones raging, these play a big part in pregnancy. They impact everything, from the bloodstream to the mood swings and even play their big role in weight gain and swelling feet. Ugh, hormones.

However, there are plenty of important, and more subtle, things that the hormones are doing along the way. The fact that they’re doing something for your baby’s lungs as well is pretty cool. And they’re not making a big deal of it either, which is a nice change. Good work, hormones.

So basically, once baby is born, the lungs are still filled with some of that leftover amniotic fluid. No one wants this is the real world, so it’s gotta be drained. This is where your hormones kick into gear and help to drain the leftover liquid. This chemical reaction means that baby can breath in air while the hormones drain the liquid and while you take a breath and realise delivery is over!

5 It Takes 4 Weeks For Lungs To Start Forming

Not a whole lot really happens in 4 weeks, realistically. Unless an amazing vacation is taking place, on average 4 weeks means a standard working month and the standard weekends. It’s not an insignificant amount of time, but it’s not an amazingly long amount of time either.

Therefore, it is even more impressive that lungs are able to start forming in the fetus after just 4 weeks from conception. Think about it, you might not even know that you’re pregnant at 4 weeks! Sure, these aren’t actual lungs forming, rather the cluster of cells that is making its way onto becoming a fetus start branching off into sections.

One of the sections that the cells starts creating is the lungs. The lung development starts at week 4 and continues through to about week 7, as the cells need plenty of time to figure out where the future lungs are going to be.

4 Air Sacs Are Ready But Not Functional

Throughout all the stages of lung development in utero, the air sacs are making their way to centre stage. From the embryonic phase to the alveoli stage, the air sacs are getting bigger and bigger and doing their best to play their part.

When babies are first born, they have around 50 million air sacs in their lungs. These are the air sacs that kick start their first breaths on the outside of the womb. However, because these air sacs aren’t fully developed, babies will typically need a hit of oxygen when they are first born to ensure their lungs are getting enough air.

The air sacs are basically ready once they’re developed in the womb. But the reason they aren’t fully functional is because the blood vessels haven’t fully triggered yet with oxygen. In the womb, the air sacs can’t actually receive oxygen since they’re surrounded by all that amniotic fluid. Therefore, it isn’t until oxygen is first breathed in that the capillaries and air sacs really work together.

3 Baby Bodies Produce A Breathing Chemical

The fetus gets up to some pretty interesting stuff in the uterus while it is figuring out how to function and all that. Amongst the bizarre stuff going on, there are a whole lot of chemical reactions that are preparing all the organs to function outside the womb.

Within the fetus’ lungs, there are two proteins that work together to create a chemical reaction. This essentially becomes a breathing chemical as it is what sparks the movement of inhaling and exhaling the amniotic fluid while still in the womb. These tend to activate in the lungs towards the end of pregnancy.

What’s even more interesting is that these two proteins are thought to trigger labor! As the proteins come together, the substance called surfactant is released so that the baby is prepared to breath air on the outside. Once proteins SRC-1 and SRC-2 get together and flare the lungs up, the party really starts.

2 Air Sacs Keep Developing After Birth

Initially air sacs start developing during the alveoli stage. This is when the lungs really start kicking into gear in the womb and the arteries and veins branch out and follow the growth of of the lungs. The air sacs start developing too, with capillary blood vessels forming around the air sacs.

At this point, the lungs are developed, but not fully functioning. The air sacs are ready to inhale and exhale air, but only in small amounts to start with. The more they develop on the outside, the more air they can handle.

Adults have 300 million air sacs on average, but your baby only has 50 or 70 million when they enter the world. It sounds like a lot, but obviously there’s plenty of scope to develop some more air sacs. This all comes in time and when they are needed. After all, a tiny baby doesn’t need 300 million air sacs, that’s just greedy!

1 Segregated Cells Create Lungs

From the point of conception, what is going on inside the uterus is basically a cluster of cells. Over time, this cell cluster is going to form its way into a fetus and eventually pop out into the world as a beautiful new born baby. All this happens in 9 months, which is a pretty impressive time frame to go from cell ball to crying, screaming, pink faced cherub.

Along the way, the cells start doing incredible things and finding their required course of action. This is rather remarkable since no one is actually giving the cells an instruction book on where they’re meant to be. Science and biology just take that one away like pros.

As the cells start separation and segregating from the initial cell ball cluster, this is when organs start forming. The lungs break off from the cell cluster and take their stance, creating a cluster of lung cells. Eventually, these cells start forming the finer details of actual lungs. But they’ve got 9 months to do that!

Sources: Livehealthy.chron.com, Embryology.ch, Blf.org.uk, Livestrong.com

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