Things about the human body I did not learn about in med school

[ForbiddenComma]

Despite four years of medical school, there are still some things about the human body that mystify me. I want to ask students closer to their physiology classes than me about a few vital issues that require clarification before I begin my residency in July.

I should note that my residency will be in pediatrics, and presumably these will be things on the minds of my patients, as well as my own equally immature mind.

1. What is the physiology behind boogers? Why do they exist? And how are they naturally cleared if one does not pick their nose? I assume they are naturally driven back to the nasopharynx and then swallowed... is this true?

2. Why is poop almost always brown? As opposed to blue, green or purple? I know there are a few exceptions, such as after you drink red wine... but 99% of the time, poop is brown no matter what you eat, assuming your liver and pancreas work. Why is this?

3. Has anyone ever suffered intestinal perforation from holding in their farts for too long?

4. What is the physiology behind determinate hair (i.e. short-and-curlys) in the groin and axillary regions? And are they somehow related to the apocrine glands in these same regions that are responsible for B.O.?

I, and my future patients, await your responses, good med students of America. Thank you for your help.

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[reedman]

ib4c

 

[Jay Leno]

Despite four years of medical school, there are still some things about the human body that mystify me. I want to ask students closer to their physiology classes than me about a few vital issues that require clarification before I begin my residency in July.

I should note that my residency will be in pediatrics, and presumably these will be things on the minds of my patients, as well as my own equally immature mind.

1. What is the physiology behind boogers? Why do they exist? And how are they naturally cleared if one does not pick their nose? I assume they are naturally driven back to the nasopharynx and then swallowed... is this true?

2. Why is poop almost always brown? As opposed to blue, green or purple? I know there are a few exceptions, such as after you drink red wine... but 99% of the time, poop is brown no matter what you eat, assuming your liver and pancreas work. Why is this?

3. Has anyone ever suffered intestinal perforation from holding in their farts for too long?

4. What is the physiology behind determinate hair (i.e. short-and-curlys) in the groin and axillary regions? And are they somehow related to the apocrine glands in these same regions that are responsible for B.O.?

I, and my future patients, await your responses, good med students of America. Thank you for your help.

Not in medical school yet (starting in august), but some of my college professors did touch upon these:

3. It's possible if there is a bowel obstruction - however, I don't think that this is likely to happen if someone voluntarily tries to hold it in. The rectoanal reflex is more likely to cause the voluntary muscles around the anus to start spasming before the fart reaches a sufficient pressure to tear holes in the intestine.

4. The groin and axilliary regions have apocrine glands that are not present on any other parts of the body. These glands secrete phermones. So it's possible that the short curly hair are meant to retain the sweat around those area to help disappate the phermones.

 

[DarknightX]

Also, why is it that then you have a stuffy nose, sometimes one nostril is stuffed up, then for no apparent reason it switches to other nostril. Then sometimes both nostrils are stuffed up again. I have always wondered this.

 

[hoqhuuep]

Boogers = nasal mucous gland secretions dried out by the constant stream of air, plus whatever particles are stuck in there (dust, etc).

 

[Jolie South]

Boogers = nasal mucous gland secretions dried out by the constant stream of air, plus whatever particles are stuck in there (dust, etc).

Yes, but the question is where do they go if you don't pick your nose?

As far as poop coloration goes, that's just the color of stercobilin (ultimate breakdown product of hemoglobin in feces).

 

[deleted191570]

Also, why is it that then you have a stuffy nose, sometimes one nostril is stuffed up, then for no apparent reason it switches to other nostril. Then sometimes both nostrils are stuffed up again. I have always wondered this.

I think you're talking about the nasal cycle. The ENTs keep mentioning this.

http://en.wikipedia.org/wiki/Nasal_cycle

 

[Jolie South]

I think you're talking about the nasal cycle. The ENTs keep mentioning this.

http://en.wikipedia.org/wiki/Nasal_cycle

I rotated on ENT already and I never managed to hear this. Weird.

 

[Knicks]

The color of feces (and urine for that matter) is due to urobilin.

 

[guestdoc]

I think you're talking about the nasal cycle. The ENTs keep mentioning this.

http://en.wikipedia.org/wiki/Nasal_cycle

I heard basically the same thing. In class they mentioned the "swell bodies" as well (which I didn't see in the wikipedia article), which I basically equated to alternating tissue-balloons getting engorged one at a time. We talked about how it could be that way so that the inside of each nostril can take turns warming and humidifying the air and not get too dried out.

Also, I think that both can swell at the same time because sometimes when I'm sick I know for a fact there is no snot in my nose (I'd blown my nose so hard I was getting a headache) yet I couldn't breathe out of either nostril. Some sources (found by searching for "swell bodies" in google):

"The nasal mucosa is highly vascular, and it warms and moistens the incoming air. The mucosa contains large venous-like spaces ("swell bodies"), which may become congested during allergic reactions or infections." http://www.dartmouth.edu/~humananatomy/part_8/chapter_52.html

"The nasal swell body is a widened region of the septum located superior to the inferior turbinates and anterior to the middle turbinates, and of potential importance to the airflow-regulating nasal valve." http://www.otojournal.org/article/S0194-5998(04)01184-2/abstract

 

[Siggy]

Yes, but the question is where do they go if you don't pick your nose?

As far as poop coloration goes, that's just the color of stercobilin (ultimate breakdown product of hemoglobin in feces).

...and that's why hemoglobin is awesome. It colors both your poop and your pee and manages to get them to be different colors!

 

[kayakjack]

http://www.onlineschools.org/blog/facts-about-poop/

 

[phantomx87]

http://www.onlineschools.org/blog/facts-about-poop/

 

[ForbiddenComma]

Most educational! A pity these things were left out of my med school coursework. I must write a strongly-worded letter to the dean. Thank you.

 

[mjl1717]

I think you're talking about the nasal cycle. The ENTs keep mentioning this.

http://en.wikipedia.org/wiki/Nasal_cycle

Great info jwl...Funny how not even many pathologist know this!!!!

 

[RySerr21]

the color of stool is definitely known and taught during med school....it should be in any basic physio textbook under breakdown of RBCs. Two of the products of heme breakdown are uroblin and stercobilin. Urobilin is peed out and has a yellowish color. Stercobilin is pooped out and has a brown color.

 

[thechad]

the color of stool is definitely known and taught during med school....it should be in any basic physio textbook under breakdown of RBCs. Two of the products of heme breakdown are uroblin and stercobilin. Urobilin is peed out and has a yellowish color. Stercobilin is pooped out and has a brown color.

It should be noted that urobilin and stercobilin are actually the same thing, and many textbooks aren't using the term stercobilin anymore. At least that's what I learned.

 

[ForbiddenComma]

I learned the pee thing but never the poop thing... guess I must've slept throught that lecture. I don't forget the important stuff.

 

[hrandani]

1. What is the physiology behind boogers? Why do they exist? And how are they naturally cleared if one does not pick their nose? I assume they are naturally driven back to the nasopharynx and then swallowed... is this true?

2. Why is poop almost always brown? As opposed to blue, green or purple? I know there are a few exceptions, such as after you drink red wine... but 99% of the time, poop is brown no matter what you eat, assuming your liver and pancreas work. Why is this?

3. Has anyone ever suffered intestinal perforation from holding in their farts for too long?

4. What is the physiology behind determinate hair (i.e. short-and-curlys) in the groin and axillary regions? And are they somehow related to the apocrine glands in these same regions that are responsible for B.O.?

I, and my future patients, await your responses, good med students of America. Thank you for your help.

Farts are absorbed by the intestine into the blood and then are breathed out by the lungs if they aren't expelled - so no you can't get an intestinal perforation. BO is produced by bacteria, not the apocrine glands, although they are digesting the products. Poop is always brown due to the liver's digestion of blood cells. Short and curlies though, I'm at a loss.

 

[Speculatrix]

Excellent questions!

Years ago I remember thumbing through a book at a medical school bookstore, written by doctors, targeted to other doctors (?? I think??) on answers to questions that doctors should know the answers to... / questions frequently asked to doctors, that aren't covered in medical school. I wish I had purchased that book, but I totally forgot the name of it or anything else about it! Anyone ever see this book or know what I'm talking about?

 

[Parts Unknown]

4. What is the physiology behind determinate hair (i.e. short-and-curlys) in the groin and axillary regions?

Perhaps to dissipate friction.

Axillary hair to deal with arm motion, groin hair to deal with the bump and grind.

 

[Freezer]

the apocrine glands associated with axillary and pubic hair, as previously mentioned, may have a function in pheromones... but also pubic hair acts as a very distinct "red flag" for sexual maturity... that isnt necessarily important today... but if you rewind the anthropological clock several thousand years... it was a matter of survival for the species... think about what it takes to gestate, deliver, and raise a child... infants have no ability to survive on their own in the wild... but what about a 5 year old... or a 13 year old... many anthropologists would argue that early humans would probably be mature enough to survive on their own somewhere between the ages of 10 and 14... that means the parent, in order to pass along their genetic information successfully, would need to be alive for 10-14 years after delivery to raise that child... well, if you reach sexual maturity at the age of 12 or so... and your chances of surviving dramatically decline past the age of 30 as would be the case in several periods of early human history... well, that leaves a very short window for reproduction... and any little morphological hint that allows you to know immediately if you or a potential mate are capable of conceiving a child is an advantage that may keep your species alive...

now i know a lot of people would argue that pubic hair does not necessarily equal sexual maturity... and i agree... however, if you are thinking parametrically, its close enough to be effective in this case...

a little bit of a side note... i also find it interesting how many behavioral and emotional changes occur in children within that 10-14 year age range... they start to become much more independent and begin venturing away from the "nest"... with the above train of thought it sort of makes sense... pretty hard to concieve a child when mom and dad are watching...

 

[phospho]

I totally forgot the name of it or anything else about it! Anyone ever see this book or know what I'm talking about?

haha, i loved the book. Had to go back to my amazon orders in 2008 to remember the name.

Why Do Men Have Nipples? Hundreds of Questions You'd Only Ask a Doctor After Your Third Martini.

http://www.amazon.com/gp/product/1400082315/ref=oss_product

If I remember correctly, in the first page of the book, the author mentions that the book is written for doctors.

 

[Knicks]

Farts are absorbed by the intestine into the blood and then are breathed out by the lungs if they aren't expelled - so no you can't get an intestinal perforation. BO is produced by bacteria, not the apocrine glands, although they are digesting the products. Poop is always brown due to the liver's digestion of blood cells. Short and curlies though, I'm at a loss.

Can that be one factor contributing to bad breath?

 

[Speculatrix]

haha, i loved the book. Had to go back to my amazon orders in 2008 to remember the name.

Why Do Men Have Nipples? Hundreds of Questions You'd Only Ask a Doctor After Your Third Martini.

http://www.amazon.com/gp/product/1400082315/ref=oss_product

If I remember correctly, in the first page of the book, the author mentions that the book is written for doctors.

THANK YOU. It is so random that I remembered that "written for doctors" thing and nothing else. Did you learn anything useful from it?

 

[phospho]

Did you learn anything useful from it?

I think the author's goal might have been entertainment, rather than a book that's only full of factoids. But I definitely learned quite a bit, and I think the facts stuck with me because it was a pretty funny book.

I can't remember anything specific, but I do recall being able to answer a few of those weird questions we all get every now and then at the bar or at home. Wouldn't have been able to answer them w/o having read the book

(plus its like $0.01 on amazon, so you only pay the 3 bucks for the shipping)

 

[armybound]

I always heard of the one nostril at a time thing as "swell bodies" that periodically switch to lessen dessication on eat nostril.

 

[Dirt]

1. Snot rockets!

 

[redsquareblack]

It should be noted that urobilin and stercobilin are actually the same thing, and many textbooks aren't using the term stercobilin anymore. At least that's what I learned.

My understanding (limited though it may be) is that while the two are related, they aren't the same thing.

 

[thechad]

My understanding (limited though it may be) is that while the two are related, they aren't the same thing.

I'll take Dr. Goljan's words over yours.

 

[shreypete]

No they're not the same structurally. Functionally however, both are derived from the catabolism of Heme and I think both compounds are responsible for imparting brown color to the feces.

 

[cetona]

I'll take Dr. Goljan's words over yours.

You're thinking of stercobilinogen, which is the same thing as urobilinogen. Urobilin and stercobilin are different.

 

[thechad]

You're thinking of stercobilinogen, which is the same thing as urobilinogen. Urobilin and stercobilin are different.

Ah, my bad.

 

[ducki303]

I would like to refer you all to:

"Beakman's World" and " Bill Nye the Science Guy"


I used to watch this all the time. I absolutely remember the episode where they explained what boogers are -- complete with a giant model of a nose. http://www.billnye.com/Tried to find the clip for you all but I could find it.

 

[Zoom-Zoom]

Stercobilin, stercobilin.

I'de like to know why people die so quickly when they bleed out. Like, for example, when a dude gets shot in the movies and dies in like 3 seconds, Saving Private Ryan style. Or, for example, why fainting can occur due to super-transient lacks of blood flow. How does this happen histologically? Can neurons really die so quickly? I'd think there'd be some brain activity for a good 10 minutes at least with no blood flow. Is consciousness really so fragile?

 

[SocialistMD]

I'de like to know why people die so quickly when they bleed out. Like, for example, when a dude gets shot in the movies and dies in like 3 seconds, Saving Private Ryan style.

I hope you realize they don't; that is a Hollywood phenomenon that doesn't exist in the real world. Some people faint and then never regain consciousness, but even people who suffer aortic transections or decapitations "live" for several seconds to minutes.

 

[Mr hawkings]

Stercobilin, stercobilin.

I'de like to know why people die so quickly when they bleed out. Like, for example, when a dude gets shot in the movies and dies in like 3 seconds, Saving Private Ryan style. Or, for example, why fainting can occur due to super-transient lacks of blood flow. How does this happen histologically? Can neurons really die so quickly? I'd think there'd be some brain activity for a good 10 minutes at least with no blood flow. Is consciousness really so fragile?

The brain cannot survive for very long without oxygen or glucose (nor can it tolerate even small amount of lactate build-up) so loss of conciousness would come relatively fast (probably not in seconds though) but my guess is death would probably take a few minutes.

 

[Zoom-Zoom]

I hope you realize they don't; that is a Hollywood phenomenon that doesn't exist in the real world. Some people faint and then never regain consciousness, but even people who suffer aortic transections or decapitations "live" for several seconds to minutes.

Yeah that makes sense. Still doesn't explain fainting though...

 

[ratbandit]

Does anyone know why your legs sometimes get itchy when you run??? I've always wondered why this happens.

 

[Jolie South]

Does anyone know why your legs sometimes get itchy when you run??? I've always wondered why this happens.

I've noticed that I get the itches in more fatty parts of my body. I like to tell my self that it's the fat burning away.

 

[weightyheart]

How does one human convince another human to have sex?
When and where is it appropriate to have sex?

Came to medical school to find the answers to these questions, but they have not yet been covered in the syllabus or lectures. Wasted $100k for nothing.

 

[ducki303]

Does anyone know why your legs sometimes get itchy when you run??? I've always wondered why this happens.

I always thought it was just me who had this experience. Still don't know the answer to this.

 

[punkedoutriffs]

How does one human convince another human to have sex?

You must've been dozing in pharmacology and thus missed the section on roofies.

 

[caniac]

Does anyone know why your legs sometimes get itchy when you run??? I've always wondered why this happens.

I always just assumed it was razor burn

 

[Grouphug]

Does anyone know why your legs sometimes get itchy when you run??? I've always wondered why this happens.

Isn't it just because sweat makes you itchy? Hopefully I'm not spreading falsehoods...

 

[Druggernaut]

I think it's because of exercise-induced histamine release.

Not the exact same symptoms, but here's something on the same spectrum: http://www.medicinenet.com/script/main/art.asp?articlekey=79103

But more importantly, what caused you to bump this 2.5 year old thread?

 

[neusu]

Also, why is it that then you have a stuffy nose, sometimes one nostril is stuffed up, then for no apparent reason it switches to other nostril. Then sometimes both nostrils are stuffed up again. I have always wondered this.

It's the nasal cycle http://en.wikipedia.org/wiki/Nasal_cycle meant to allow the nose to build up and flush out mucus, particles, etc.

 

[VenusinFurs]

I think it's because of exercise-induced histamine release.

Not the exact same symptoms, but here's something on the same spectrum: http://www.medicinenet.com/script/main/art.asp?articlekey=79103

But more importantly, what caused you to bump this 2.5 year old thread?

This is a good thread. Bumping an old thread is only dumb if it's about a dilemma someone was having at the time and you are offering them advice even though they are now in an entirely different plane of existence.

 

[Druggernaut]

This is a good thread. Bumping an old thread is only dumb if it's about a dilemma someone was having at the time and you are offering them advice even though they are now in an entirely different plane of existence.

I do like the thread, and I have no problem with it being bumped, but he was answering a question from a poster who hasn't been on SDN since he asked it over two years ago.

It sounded more hostile than I intended. I thought it was funny, and honestly do wonder how it happens that people bump old threads on bizarre topics, both for how they came across it and what prompted them to resurrect it.

 

[Tipsy McStagger]

I do like the thread, and I have no problem with it being bumped, but he was answering a question from a poster who hasn't been on SDN since he asked it over two years ago.

It sounded more hostile than I intended. I thought it was funny, and honestly do wonder how it happens that people bump old threads on bizarre topics, both for how they came across it and what prompted them to resurrect it.

Sometimes when I google something, a thread from a forum shows up in the results. I usually click it because it answers what I'm looking for. It does happen that I'll occasionally post to that thread, only to discover it's a few years old.

Anyways this thread is funny. I just bought the nipple book for $0.01... $3.00 shipping