I’m talking about the open spaces that in children and adults are filled with air. But that doesn’t seem likely for a being that’s conceived in an essentially liquid environment. How does it happen that the lumen is not filled with some liquid? Or is it? Is that what meconium is? Similar to the question of how does a pumpkin grow with a body filled with air?
Meconium is fetal stool, formed from swallowed amniotic fluid which mixes with fetal intestinal secretions (which are chock-full of shed cells). Amniotic fluid also fills the lungs and many other potential air spaces. No air is present in fetal lungs/bowels etc as a rule, unless some sort of gas-forming process is occurring, usually a deadly infection. Passage thru the birth canal during delivery squeezes out the fluid in the lungs and prepares the newborn to refill the lungs with air. C-section babies tend to need more vigorous respiratory stimulation at birth due to their lungs tending to have more fluid in them.
I’ve not delivered any pumpkins so can’t comment there.
The GI tract is also supposed to be sterile; it takes several days for the gut to colonize with bacteria that aids in the digestion of milk and the production of vitamin K. The bacteria is obtained through breathing room air, and also from the nipple, whether it’s Mom’s or one attached to a bottle.
This is true for mammals in general, and since Qadgop mentioned c-sections, animals delivered that way have a very high risk of death for precisely that reason. I follow several kitten rescue cams, and this is only a very last resort.
Bang! Thread winner in one! You sure?
I don’t know if this is a sub-question you wanted answered, but:
Pumpkins grow
Pumpkins are not completely airtight
Not too much to add except to point out that it doesn’t take very long for the air to get there after birth.
By ten minutes or so there is air in the stomach, within a few hours the small intestines have bubbles and the large intestines by half a day.
That would be the lungs. And so far as I know, only the lungs.
Why would the stomach and intestines be filled with air, instead of just empty?
I thought large intestines have obligate anaerobes, and the large intestine in general is anaerobic !
Even the fetus has gut bacteria and it’s transmitted from the mother
More response than you may be looking for -
First the gas that is in the large intestine within hours is passed down from above. And there is that gas in the large intestine in adults as well as kids. It is however a fairly low oxygen environment, especially in the lumen, with relatively higher oxygen levels near the mucosa.
Second the mature microbiome of the large intestine has obligate anaerobes … 90% roughly … 10% is not, The microbiome itself helps to regulate the oxygen level.
Third, the newborn large intestine is seeded with aerobic and facultative anaerobic bacteria. These consume oxygen, creating the relatively hypoxic environment that leads to obligate anaerobes predominating later. The process takes several years.
Very interesting. Following the link to the article it appears that the fetal microbiome mostly serves an immune training function and is apparently mostly or completely gone by term, with the gut then seeded after birth, primed for it by this earlier exposure.
Cool!
Our stomachs and intestines aren’t filled with air. It would be easy to get that impression looking at anatomical diagrams in which these structures are depicted as appearing “full,” but in reality, when they’re empty, they’re just collapsed on themselves, like a balloon.
Apparently they are watertight because I’ve seen videos of them being used as boats.
But that’s over a few minutes. Would water make it through over the course of a few months?
Better question: Would a pumpkin grown underwater be filled with air or water (presuming it could actually grow underwater)?
What if you put the pumpkin on a treadmill? Underwater?
Serious musing: does the air inside a pumpkin originate from outside or by way of cellular respiration, both of the plant’s cells and of commensurate organisms?
I suspect the latter.
Trying to answer my own musing I found this for a different but likely comparable hollow fruit, bell pepper.
http://www.madsci.org/posts/archives/2006-07/1152918612.Bt.r.html
The gas composition inside the fruit is different than outside air, significantly higher in CO2, produced by cellular respiration. The inside of a fruit in fact is fairly air tight!
That underwater pumpkin would be filled with air.
I was with you until the analogy with a balloon… 
Well, I thought of a whoopee cushion too, but felt that given that we’re already talking about intestines, the resultant fart jokes would be too distracting.
Not sure the conclusion necessarily follows there. My car isn’t airtight, but if I fill it with people who consume the oxygen, the CO2 level will rise inside. All that is necessary for that to happen is that the rate of respiration is out of pace with the rate at which gas is exchanged with the outside.
Fair point.