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CharlesOSmith t1_iuhrqly wrote

You are right, it is surprisingly difficulty to find the type of information you are asking about when you include the word "fever" in your search.

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Our body heat is regulated by our body's ability to balance of how much heat we generate and how much heat we lose to the environment.

Here are some examples of heat production (notice how many are simply the result of normal metabolims):
-Basal metabolism

-Muscle activity, by shivering and muscle contractions

-Extra metabolism caused by the effect of sympathetic stimulation and norepinephrine, -epinephrine on the cells

-Extra metabolism caused by increased chemical activity in the cells, especially when the cell -temperature increases

-Extra metabolism caused by thyroid hormone and, to a lesser extent, testosterone and -growth hormone on the cells

-Extra metabolism needed for digestion, absorption, and storage of food

-Most of the heat produced in the body is generated in the liver, brain, heart, and skeletal -0--muscles during exercise.

And we balance that by also regulating mechanisms of heat Loss which is determined almost entirely by:

-How rapidly heat transfers from the skin to the surroundings

-How rapidly heat is conducted from where it is produced in the body core to the skin

https://www.ncbi.nlm.nih.gov/books/NBK499843/

A fever triggers an adjustment of where that balance is, so as metabolic processes are triggered to run hotter, our circulatory system is triggered to allow less heat loss through our skin, and we don't sweat.

The term "a fever broke" is referring to a person who after a fever has begun to sweat to allow for the rapid loss of all that heat.

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https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4786079/

Fever induction and signal transmission

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Agouti t1_iui6bf8 wrote

You forgot an important mechanic - perceived body temperature. People with serious fevers often feel cold and actively take steps to warm up (e.g. warmer clothes).

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CharlesOSmith t1_iui6voe wrote

That's part of resetting the internal thermostat, so I didn't include it as one of the biochemical mechanisms for generating the heat, but its a good point.

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[deleted] t1_iuikiiq wrote

[removed]

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awakened_celestial t1_iujzgkb wrote

I’m just like you. I never get fever temperatures even if I’m sick. I also get cold in the summer even if it’s hot outside. I can also manually lower my body temperature with some given time and effort and I’m learning how to raise it. Even if I get really really sick I still don’t get a fever.

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CaffeineSippingMan t1_iui4u3h wrote

If we are allowing less heat loss, why do we feel warm on the forehead?

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Kraz_I t1_iuio4x6 wrote

Your body can’t stop dry heat from conducting out. If the blood in the vessels of your brain and head are hotter than normal, then you will feel warmer to the touch. There’s no way for your body to become more insulating except by wearing more layers or a blanket. The amount of heat lost via dry conduction is much less than what would be lost due to sweat. Water carries much more heat than air, and when it evaporates, it also removes more heat by conduction. That’s why if you get sweat on your shirt and then move to a place at room temperature, your shirt will feel uncomfortably cold.

Also when you feel someone’s forehead, your hand is a better heat conductor than air, and your hands and extremities also tend to run colder than your core body temperature, so foreheads feel warm to the touch even at normal temperatures.

I don’t have a background in physiology, but in materials science, so I understand heat conduction. If I made a mistake, someone who knows could chime in

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PatrickKieliszek t1_iujc2s4 wrote

Although evaporation dominates as a method of heat loss, there are two biological mechanisms that I am aware of that can additionally decrease dry conduction.

Capillary constriction in the skin reduces blood flow and makes the skin a more efficient insulator.

Piloerection of hair follicles helps trap air against the skin and improve insulation (works better on hirsute people and is mostly redundant in people that wear clothing).

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an711098 t1_iujoqqg wrote

Do you happen to know how capillary constriction transmits across other organs? Would it be fair to assume that if the capillaries in our skin constrict, capillaries in other parts of the body are constructing too? E.g. I recently read a summary (layperson here) of a paper suggesting Covid 19 triggers capillary constriction in the brain and am wondering if that triggers manifestations in other organs? Or if the circulatory system is big enough that capillaries in one part of the body don’t have to experience the same fluctuations as another (provided no mechanical separation like a tourniquet or tumour or whatever)?

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JCoco17 t1_iuk7b8s wrote

Different systems respond to different messages. Brain and muscles increase blood flow, while digestion decreases blood flow under stress.

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FunnymanDOWN t1_iuj0n2e wrote

Offshoot question: how high of a temp. Can a human body get to on it’s own?

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CharlesOSmith t1_iuj1wyg wrote

according to NPR the record is:

115 degrees: On July 10, 1980, 52-year-old Willie Jones of Atlanta was admitted to the hospital with heatstroke and a temperature of 115 degrees Fahrenheit. He spent 24 days in the hospital and survived. Jones holds the Guinness Book of World Records honor for highest recorded body temperature.

https://www.npr.org/sections/goatsandsoda/2014/11/14/364060441/you-might-be-surprised-when-you-take-your-temperature#:~:text=115%20degrees%3A%20On%20July%2010,for%20highest%20recorded%20body%20temperature.

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LakierskiMaterialski t1_iuja1z9 wrote

for the 95% of the earth's population that don't use cheeseburger units - that's 46 celsius

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bmacnz t1_iuj8e08 wrote

While good and interesting info, I feel like that doesn't qualify as on its own. With a heatstroke aren't their external factors raising the body temperature?

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123rune20 t1_iujj3cj wrote

I mean fevers are always in response to some external factor, no? Heat stroke, infection, medications, etc.

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bmacnz t1_iujl73x wrote

What I mean as external heat source, not just a cause of a fever. An infection is not actually hot itself, your body temp is rising in response to it. In the case of a heatstroke, there's literally heat being added to your system, not just your body responding to stimuli.

It's like with hypothermia, your body isn't cooling down on its own, the freezing air/water is doing it.

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FunnymanDOWN t1_iujg2qf wrote

The rest of the world Profiting off American innovations while complaining. Typical lol

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CTH2004 t1_iujd484 wrote

> -growth hormone on the cells

does that mean someone who's growing has a higher body tempature?

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Also, is the Fever caused by using more nutrients to kill the pathogen, (As the liver, as you said, already produces lots of heat)

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zman0313 t1_iuk3tn2 wrote

A lot of heat is generated during growth and also regeneration in the body (recovering from exercise). It’s often localized in joints and bones and takes time to dissipate, so probably won’t raise temperature much wherever you’re sticking the thermometer.

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