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probes
24th Jan 2015, 15:08
How would you explain fever with the laws of energy (or thermodynamics)? How does the body produce so much heat, sometimes within minutes? OK, there are the pyrogens (Why does your body temperature rise when you have a virus such as the flu? - HowStuffWorks (http://science.howstuffworks.com/life/cellular-microscopic/question45.htm)), but what about the conversion or transfer or whatever? :uhoh:

con-pilot
24th Jan 2015, 19:34
How would you explain fever with the laws of energy (or thermodynamics)? How does the body produce so much heat, sometimes within minutes? OK, there are the pyrogens (Why does your body temperature rise when you have a virus such as the flu? - HowStuffWorks), but what about the conversion or transfer or whatever?

I don't think that is a stupid question to a medical layman, however, you can ask 421dog, he is a doctor and probably knows the answer.

421dog
24th Jan 2015, 20:39
So, in a nutshell, in response to the stimulus that tells your body to heat up (dead or dying cell products in the case of a viral infection, microbial products either excreted or intrinsic, in the case of fungal or bacterial infections, the hypothalamus (a chunk of the brain) is stimulated to up the body's temperature set point (primarily by stimulating the production of thyroid stimulating hormone and direct stimulation of the sympathetic nervous system).

This produces vasoconstriction, which limits heat loss, and shivering, which relies primarily on glycolysis, which is an exothermic process.

Now, babies and some of the arctic tribes are able to more or less directly produce heat by way of brown fat, which the rest of us lack. Basically, this stuff lets you turn energy in the form of glucose (which can, albeit in a metabolically expensive way, be produced from regular old fat) directly into heat. (basically what happens is known as "futile metabolism", the body breaks down glucose, makes fat, and breaks down the fat to make more glucose, all without sending the products of the glucose breakdown to the liver, where it would be used to make much more energy (ATP).

That all being said, in certain circumstances, the body gets confused and uses the process to cook itself (like in Malignant Hyperthermia, or Neuroleptic Malignant Syndrome, both conditions in which the resultant fever is almost invariably fatal if not dealt with promptly), or when the temperature gets below about 28 C, we just stop trying, and become poikilotherms and assume the temperature of our surroundings.

421dog
24th Jan 2015, 20:40
Surgical infectious disease is sort of my specialty, so I'd be happy to expound, should you so desire.

meadowrun
24th Jan 2015, 20:44
Increase in the metabolic rate to fight the infection.


Ever hold a baby bird? They are hotter than you are, which is why you shouldn't handle them as your temp will decrease their temp. They are growing very rapidly and the furnace to power that burns hot.

probes
24th Jan 2015, 20:59
thanks a lot!
So, could we say fat is 'converted' into heat? :ouch:

421dog
24th Jan 2015, 21:29
Well, it is if you are possessed of significant amounts of brown fat, or if you are in a starvation state (running on ketones rather than ingested carbohydrates/proteins).

What it boils down to is that most of us make heat via muscle contractions, be it useful contractions (like when doing work)
or contractions purely for the sake of making heat (shivering, jumping up and down outside the bar in Winnipeg, stamping your feet and clapping your hands together while waiting for a shot at an adult beverage and a decent hockey game)

The thing to remember is that we have an enormous capacity to make heat, and if your hypothalamus wants to do it, your only real chances of short-circuiting the process involve limiting the stimulus (anti-pyretic meds or fixing the problem), preventing muscle contractions (relaxants like Dantrolene or Paralytic meds), or overwhelming the body's ability to make heat (like an ice bath; fans and cool cloths just make the hypothalamus cranky)

The body works hard to make fat, and it does a lot to hold onto it.

That being said, calories are calories, and if you're out in the cold, your metabolic rate increases markedly to compensate, so even if you aren't actually burning fat, you're making less for the same amount of caloric intake.

Loose rivets
24th Jan 2015, 23:58
Then there was Jane Russel getting into bed with erm, was it John Wayne??? or someone of that ilk, to get him cooled down.

ruddman
25th Jan 2015, 04:28
If that's your 'in a nutshell', 421dog, I'd hate to see the normal version. :cool:


Some of us, probes, just make a lot of heat. Ask Mikedreamer. He's on heat permanently. :}

For me, it's just a matter of being a well built man with lots of hard, lean muscle. Yes, I know. My wife is the luckiest girl in the world. :ok:

probes
25th Jan 2015, 12:40
ok, next:

how can crows sit on branches that are way too thin to possibly bear their weight?

https://www.colourbox.com/preview/2040204-black-raven-crow-on-the-tree-branch.jpg

421dog
25th Jan 2015, 12:47
Skyhooks, of course.

dazdaz1
25th Jan 2015, 16:13
421dog...... "That all being said, in certain circumstances, the body gets confused and uses the process to cook itself"

Well that's the mystery of Spontaneous Human Combustion sorted.

Choxolate
25th Jan 2015, 16:16
ok, next:
how can crows sit on branches that are way too thin to possibly bear their weight?
OK serious answer - although crows (and many other birds) look quite large they are surprisingly light having evolved to be so by having hollow bones and other weight reduction features to make flight possible.
A typical UK crow only weighs about 500 grams (just over 1 pound)

Edited to add.
Those are almost certainly rooks - crows tend to be solitary it is rooks that congregate in large numbers - and rooks are lighter than crows at about 350 grams

dazdaz1
25th Jan 2015, 16:29
Choxolate...."A typical UK crow only weighs about 500 grams (just over 1 pound)"

Very true, I recall in my younger years (16) having held a tit in the palm of my hand, it seemed so light.

Flybiker7000
25th Jan 2015, 17:16
Birds do not what, Probes?
Bird City OVER A HUNDRED OF BIRDS VIRAL VIDEO - YouTube (http://youtu.be/AynxJWNKAw8)

Flybiker7000
25th Jan 2015, 17:23
I'm rather more impressed of the bodys capability of instant face-blush wich happens quite faster than rise of fewer!
The experience of fast rising fewer is probably also due to a connected rise in skin-temperature (like the blush), wich normally is a pair of degrees lower than the inner body temperature :-/

Choxolate
25th Jan 2015, 17:49
Dazdaz1 "Very true, I recall in my younger years (16) having held a tit in the palm of my hand, it seemed so light."

Obviously not a Great Tit then.

probes
25th Jan 2015, 17:53
Flybiker, WOW! :D (the video)

and the face blush is about blood circulation and capillaries, not heat, I guess?

G-CPTN
25th Jan 2015, 18:23
I would imagine that the birds in Flybiker's video are startlings . . .

DmO4Ellgmd0

M1Q-EbX6dso

Flybiker7000
25th Jan 2015, 19:38
Read the entire posting:As for the blushings, the skin of the entire body might rise in temperature caused by blod circularion and capilaries, and this might give the impression of faster rise of fewer than actual happens!

Flyingmac
25th Jan 2015, 20:34
Those are almost certainly rooks - crows tend to be solitary it is rooks that congregate in large numbers - and rooks are lighter than crows at about 350 grams


Rooks ARE crows. They're the same size as a Carrion Crow and like the Carrion, can weigh up to 1.5lbs. The Carrion Crow also flocks. The Raven, also a crow, can weigh 1.5 kilos.

421dog
25th Jan 2015, 20:42
Blushing is a vasodilatory process and thus results in heat loss, not gain.

Think of your body as a 70 liter beaker of water. If it's at 37C, and it wants to be at 40C, that means that 3x70 (210) kcal need to be added to the system.

Increasing heat loss by blushing has the opposite effect.

When someone is becoming febrile, he feels subjectively cold, and typically exhibit dry, mottled skin especially at the distal extremeties due to the vasoconstriction which allows the conservation of heat produced by muscle contractions.

When the fever "breaks" the patient gets flushed and sweaty as he is shedding heat.

421dog
25th Jan 2015, 20:49
What's the deal with crows and ravens knowing when one is out to get them?

They will ignore someone with a shotgun hunting pheasants, but just give a thought to thinning the Corvine ranks, and they're outta there.

Flyingmac
25th Jan 2015, 20:53
It's the same with cats.

criticalmass
26th Jan 2015, 09:18
How do you know when your pen has run out of invisible ink? :(

probes
26th Jan 2015, 10:39
it becomes visible? :ouch:

Choxolate
26th Jan 2015, 12:43
Crows, rooks, ravens, jackdaws, jays, magpies are all in the same FAMILY as crows (corvidae) but they are distinct and different species. So, no a rook is not the same as a crow and ravens are different again.

BillHicksRules
26th Jan 2015, 14:35
What is Brown Fat?

Loose rivets
26th Jan 2015, 14:56
It's what fat Brown should have more of, that way he'd burn off more of the other stuff.

421dog
26th Jan 2015, 15:04
Fat cells that are specialized to produce heat directly from chemical energy.

Present in significant quantities in Neonates, arctic tribe adults and animals capable of hibernating.

The rest of us could likely do with a bit more, to keep us warm and skinny, but its presence may also be associated with excess hardening of the arteries.

KenV
26th Jan 2015, 19:34
421dog,

I get the mechanics/chemistry of how the body changes its set temperature. But I too don't understand how the body generates the calories required to increase it's temperature. Here's the math:

1 calory is required to heat 1 gram of water 1 degree C
Average human weight: 62 Kg.
Assuming:
1. a fever is an increase in body temperature of 2 degrees C,
2. the human body has the same thermal density as water,

then:
2 x 62,000 = 124,00 calories!!! How does the human body produce these calories?

Choxolate
26th Jan 2015, 20:00
124,000 calories is 124Kcal about the same as the calorific content of 3 or 4 grams of fat or of 2 or 3 cans of fizzy drink. Not a lot.

421dog
26th Jan 2015, 21:16
roughly speaking, fat contains 9kcal/gm and hydrated protein or carbohydrate contains 4 kcal/gm. That being said, 124 kcal = 124/9=13.8 gm for the job.

about an ounce of "fatty food" like donuts, olives, cocoanut etc.

Choxolate
26th Jan 2015, 21:27
I stand corrected, I was given 40KCal / gram as an average for most saturated fats

mr fish
26th Jan 2015, 22:43
5.56, 7.62, 7.92, 6.5 etc...why are weapon calibres so seemingly random.??


why not 5, 6, 7 etc??




FISH.

G-CPTN
26th Jan 2015, 22:59
Well, they are metric equivalents of previous Imperial bore dimensions (.22 and .303 etc) - but why those sizes?

6.5mm = 1/4inch.

I believe that 7.92mm is actually a metric 8mm bore size (don't ask . . . )

Windy Militant
26th Jan 2015, 23:09
Bugger beaten to it again.
Just a thought is the calibre dimension stated the bore size or the cartridge case size as I presume that it would be at the snug end of a transition fit so as to be gas tight but not an interference fit so you could be able to fit them in by hand without the aid of a Birmingham Small Arms screwdriver?

G-CPTN
26th Jan 2015, 23:19
One would have thunk that, when contemplating constructing a gun, one would have a suitably-sized tube - created by boring a hole using a readily available drill?

OTOH, one could have started with an appropriately-sized lump of lead to use as the projectile.

After all, once created (the weapon that is) one needs a ready supply of lumps to fire from it.

Windy Militant
26th Jan 2015, 23:25
That's a thunk. You need more bullets than guns, so is it cheaper to drill and ream bullet moulds to a standard size than to bore the barrels which may also be rifled! :confused:

421dog
26th Jan 2015, 23:41
....I believe that 7.92mm is actually a metric 8mm bore size (don't ask . . . )


Actually, the bullet is 8.22 mm in a 7.92x57 spitzer....

As a guy who likes to build rifles, there are an awful lot of factory calibers, and just about everything in between has been wildcatted.

probes
27th Jan 2015, 05:40
it surely was a surprise for me that the calibres are not universal (somehow I thought they are, just like the sign language, which isn't either).

Caliber - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Caliber#Metric_versus_imperial)


ok. Next:

What's the issue with the post count?
After all, it doesn't show anything reasonable (except maybe that one has fast fingers)? If posts had categories, like:
highly intelligent
smart and enjoyable
makes sense
makes no sense, but is funny
totally pointless and utterly unfunny
something like that, and forumers could vote and one got 'classified' according to the votes - well, maybe that would be something, but just post count?

Except that when the number of posts is mistaken for age... but then, one should think smart and not let it get over 18!


(P.S sorry, KAG)

Stanwell
27th Jan 2015, 06:19
To the originator, ALL of his/her posts are intelligent, clever, informative and even entertaining.
Of course, how they are viewed by others is another matter.
Keep up the good work, probes.

tdracer
27th Jan 2015, 15:56
When the fever "breaks" the patient gets flushed and sweaty as he is shedding heat.
421dog, since you are familiar with this, what exactly is happening during a fever and when a fever 'breaks'?
I recall the last time I had the flu (~25 years ago) I was driving home from visiting some old college buddies - I knew I was coming down with something but it didn't seem to be a big deal. Then, suddenly, in a matter of a few minutes, it hit me like the proverbial ton of bricks and I went from 'not feeling well' to being really, really sick. I was still ~ 50 miles/one hour from home and I was a mess - barely able to maintain the focus to keep driving (it was around midnight so fortunately there wasn't much other traffic to deal with). I had the heater turned up as high as it would go and was still shivering uncontrollably, just praying to god to keep me together ~hour so I could get home. I made it home OK, crawled into bed, and turned the electric blanket up to 11 :O. A few hours later, apparently the fever broke and I woke up sweating - ended up walking around the ~60 deg F bedroom for several minutes to cool off.
The whole episode lasted ~5 hours - I wasn't fully recovered for several more days, but it was only that short period when I was really wiped out.

rgbrock1
27th Jan 2015, 16:04
tdracer wrote:

I recall the last time I had the flu (~25 years ago)

You haven't had the flu in ~25 years? Lucky you. :ok:

tdracer
27th Jan 2015, 16:29
You haven't had the flu in ~25 years? Lucky you. :ok:

Perhaps a very mild case that I didn't recognize as the flu, but no, not a bad case. But I do make a point of getting a flu shot every year (Boeing provides them free, on-site, to their employees). The wife nearly died several years back of complications when she had a bad case of the flu, so she also gets the flu shot each year.
I tend to snicker at the people who pronounce they'll never get a flu shot :rolleyes:

con-pilot
27th Jan 2015, 18:43
Talking about something hitting you very fast and hard. One Friday we had a special run from Oklahoma City to New Orleans, then to Huston, up to Kansas City then back to OKC.

That morning I was feeling fine, by the time we got to New Orleans I was not feeling good at all, so I told the other pilot that he was going to fly the rest of the legs and I would move into the right seat for the rest of the day.

By the time we landed in Huston I was really sick. I called ops and told them that we were going to stop in OKC on our way to Kansas City and they needed to have another PIC standing by to replace me because I was so sick.

Of course ops said no, that we needed to complete the schedule. So I told them fine, that I would just get off the aircraft there in Huston and they could fly another PIC down to Huston. After that they agreed to us stopping in OKC and replacing me.

I had the FE (a type rated pilot) move to the right seat and I handled the FE panel from Huston to OKC. I got off the aircraft in OKC and drove straight home. I went to bed at around five or so and slept straight through to Sunday afternoon. My fever broke sometime Sunday and by Monday I was feeling fine.

So whatever I had, hit me quick and hard, but I was over it about as quick as it had hit me. I guess it was the flu, but I really don't know.

421dog
27th Jan 2015, 23:51
Influenza (which you both are accurately describing) produces changes in cells that result in the production of certain compounds such as interleukin 2 and Tumor Necrosis Factor both of which have a direct effect on the hypothalamus as well as on other cells. The net effect is that the body is reacting vigorously to the infected cells, and, research shows, produces a febrile response which tilts the balance in favor of the body winning the fight.

Considering the way in which viruses infect and hijack the mechanics of all sorts of cells, and considering that the body's only real option is to mark infected cells as foreign and kill them, or turn on their intrinsic self destruct mechanisms (apoptosis), it is amazing that we survive at all.

When the cytokine mess is cleaned up, the stimulus to have a fever is removed, and the body employs the usual means to cool itself off.

Checkboard
28th Jan 2015, 00:11
thanks a lot!
So, could we say fat is 'converted' into heat? :ouch:No - it isn't.

Sugars and fats are ingested, broken down by acids and bacteria and absorbed into the bloodstream. They flow through the body in the double loop of the circulation system, for use in the various cells, and the unused bits are converted into lipids for storage.

When cell output exceeds input, enzymes break down those lipids (carbon-hydrodgen molecules) (by-product = heat) using the oxygen from the lungs to end up with water and CO2. The CO2 exits via the lungs, and the water through respiration and sweat.

... So - you BREATH fat out of your body (you don't shit it out or sweat it out) :)

80% of fat leaves the body via the lungs, say experts | Daily Mail Online (http://www.dailymail.co.uk/health/article-2876319/Could-BREATHE-away-excess-pounds-80-fat-leaves-body-lungs-say-experts-exercise-better.html)

mr fish
28th Jan 2015, 20:41
I used to think the "bad" colds and chills I had over the years were always flu.
then about five years ago I caught the real thing.
as above the symptoms hit me like a hammer...fine but under the weather in the morning, a frikking wreck by mid afternoon.


this was on a Tuesday, retired to bed early as, finally woke with a throat like a swarf bin on FRIDAY night....smelling like a horse.


the wife had called the doc and kept me comfy....all seemed like a bad dream.


the first sandwich she fixed me that night never touched the sides!!!!


FISH.

probes
30th Jan 2015, 05:34
next.
How can it be that when you need a key, it's always the last one in the bunch, even if you try to cheat and start from a different one in the middle of the search?

mikedreamer787
30th Jan 2015, 05:54
No - it isn't.

Mr checkboard if you're a 320 driver then
how come you know all of this biological
shit? :confused:

The F/Os I know say that fat is burnt up
inside and blooded through the kidneys
then pissed out. A urine ketone count is
then used by doctors to verify this.

rgbrock1
30th Jan 2015, 13:49
mikedreamer wrote:

The F/Os I know say that fat is burnt up
inside and blooded through the kidneys
then pissed out. A urine ketone count is
then used by doctors to verify this.

How do the F/Os you know, know this? Are they all lard butts? :}:E

421dog
30th Jan 2015, 16:23
Really?

This conversation is on the level of a couple of doctors arguing about what makes a 747 better than an A380.

Here's a gross overview of how we metabolize major energy sources (fats, carbohydrates and proteins):http://i308.wikispaces.com/file/view/metabolism.jpg/58772752/metabolism.jpg
Would be really happy to discuss the minutiae, but saying things like "Breathing out fat" or "Pissing out ketones" is a little simplistic.

That being said, I have no idea why a B748 is better than an A380...

mikedreamer787
30th Jan 2015, 18:59
I have no idea why a B748 is better than an A380...

You don't have to except to know
a 747 of any vintage shits all over
any 380 Mr 421.

Thanks for that bio map but mon
Deu - it looks more like an Airbus
system diagram. :bored:

How do the F/Os you know, know this?

Some were med school dropouts
RGB. :\

rgbrock1
30th Jan 2015, 19:33
421dog:

Thank you very much for posting the photo of those thar hieroglyphics. Upon mulling them over my brain spontaneously burst into flames. Oh well, I've often aspired to become a babbling idiot. :ok:

ExSp33db1rd
30th Jan 2015, 22:12
I have no idea why a B748 is better than an A380...Simple - it's a Boeing.

Say n'more.

How can it be that when you need a key, it's always the last one in the bunch, even if you try to cheat and start from a different one in the middle of the search? Murphy is always with us. For the same reason when you go to check car tyre pressures the valve is always on the bottom. ( but then, it's only the bottom of the tyre that goes flat, so I guess that's alright then?)

Dark Knight
30th Jan 2015, 23:24
421Dog: Got it! Simple when explained.

obgraham
31st Jan 2015, 00:15
Though 421 must be a mite younger than I, since his chart is more filled in than the one I learned, I'm pleased to see that Acetyl Co-enzyme A is still at the center of the universe.

Some things never change.