Questions tagged [human-physiology]
For questions on the biochemical, physical, and mechanical functioning of humans in good health including their organs and cells.
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What is the relevance of the constant in the clearance equation?
I have seen the equation for drug half lives described variously as (0.7xVd)/Cl, (0.693xVd)/Cl, and (ln2xVd)/Cl.
What is the origin of this numerical constant in the numerator? What does it signify?
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Physiology of hyperpolarization
In my textbook, it is stated that after the closure of potassium voltage-gated channels and during hyperpolarization, potassium leakage channels allow potassium influx passively and this returns the ...
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Was there a time in Earth's history when some animal life existed on land but humans could not have breathed?
I understand that higher oxygen content allowed insects and arachnids to grow much larger than today and I wonder if this additional oxygen would have been toxic or unhealthy for modern humans?
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Is there a nomenclature for human physiology?
Back when I studied botany in high school, the teacher taught us the nomenclature for botanical terms. I think there should be something similar for human physiology. Understanding how the name was ...
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How does energy conversion happen (chemical to mechanical?) in moving body muscles?
From my understanding, the brain sends electrical pulses through neurons to different part of the body to initiate a movement. My question is, how is the movement realized? For example, in a train, ...
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How does the descending branch of the loop of Henle equilibrate concentration?
I'm learning physiology and I have a hard time figuring out how the cortico-papillary gradient is created.
Most explanations go as follow:
1) Sodium is pumped out the ascending branch into the ...
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Why are human wastes yellow?
Except for the feces, which is more brownish, all the human wastes (urine, earwax, snivel, phlegm, and rheum) are usually yellowish. Why is that?
I heard that urine is yellow due to bilirubin(?). What ...
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How much does capillary action contribute to blood flow to the human brain?
The BBC News Universal Wonders short video Why water is one of the weirdest things in the universe says after 01:50:
Water molecules can float upwards against the ...
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Jungle blindness?
Can people who live in green scenic areas like a jungle be more exposed to green light causing them to not be able to perceive green light as well as someone who may live in a desert void of color? ...
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Sexual Reproduction in Humans
Is the human egg cell (ova) considered motile? We know that is is not actively motile but it is transferred via the fallopian tube to the uterus. Does that make it motile?
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Partial muscle fibre contraction
I'm being taught that: a muscle fibre spans the entire length of the muscle, from the originating tendon to the inserting tendon.
The question is, can a muscle fibre contract only partially? Say, if ...
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What adaptations does the human body have to handle frequent and sustained changes in orientation?
Most animals are horizontal with the ground. When they lie down, they get closer to the ground, but their orientation does not change.
Humans, on the other hand, stand up straight and tall, ...
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RE: Fasting gastric pH vs Normal gastric pH
If fasting gastric pH values are more acidic then why is it recommended to eat no more than three hours before bed time to prevent reflux. It seems at some point during sleep the stomach would become ...
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ATP and Muscle Contraction
I have a question regarding how molecular interactions manifest in physical actions - such as hanging from a bar. To the best of my understanding, when it comes to the contraction of muscles, ATP is ...
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How do painkillers prevent shock?
I was reading about the Placebo effect and came across this little story:
The roots of the placebo problem can be traced to a lie told by an
Army nurse during World War II as Allied forces ...
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Passing out from drowning [closed]
How long does it take to pass out from oxygen deprivation? The person is panicked and screaming so they accidentally breathe water into the lungs. So how long would it take for them to pass out? After ...
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Sleeping Pill Overdose
How does an overdose of sleeping pills kill?
What are the body's reactions to an overdose?
In an article published in ScienceDaily, I read that "Sleeping pills owe half their benefit to the placebo ...
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Why does histamine cause bronchoconstriction?
What purpose does histamine-caused constriction serve in lungs during allergies and such, since it's vasodilator in other parts of body. Wouldn't it be more practical to vasodilate lungs so that white ...
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How are testosterone levels distributed among men and women?
Wikipedia tells me that men have 7 to 8 time higher levels of testosterone than women, on average.
Since the hormone is linked with performance in certain athletic events, my hypothesis, which I ...
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Is it impossible to increase skeletal bone mass, as opposed to just bone density? [closed]
I've heard exercise and resistance/strength training increases the density, but doesn't increase mass. So basically, experimentally or theoretically possible at least, can modern science do this/is it ...
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After how many hours water drunk is expelled from the body?
If one drinks a liter of water at 7 am when (in what span) will that water be eliminated through uresis?
Is that process influenced by any factors such as empty stomach, sleep or other?
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Coronary circulation
It is said that the coronary artery that gives the posterior descending artery(PDA) determines if the heart is right dominant(most cases) or left dominant. Is there any reason to this? Why PDA?
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Is it correct that the nicotinic acetylcholine receptor has nothing to do with Dopamin?
As I know Dopamine is almost exclusively produced via metabotropic receptors, is it possible for a nicotinic ACH receptor to influence a dopamineric neuron?
Can a nicotinic ACH receptor cause a ...
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Can motor neurons in the brain stem start movements?
Supposedly (consciouss) movement is started in the cerebral cortex. But some time ago I've read a research which stated it might be possible some movements (not specified which ones, probably mean ...
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Does every protein starts with Methionine amino acid [duplicate]
During process of protein synthesis we need AUG Codon to start translation .As we know this codon codes for Methionine amino acid so can we say that every protein starts with Methionine amino acid ?
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Why clotting does not occur during Menstruation
As we know when we get injured our body's clotting systems stop the bleeding. So why does it take days for menstruation to stop ?
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In oscillometric blood pressure measurement, why do we assume that highest oscillations correspond with mean arterial pressure?
As far as I've seen, the point on the oscillometric curve where there are greatest oscillations represents the mean arterial pressure (MAP).
My question is - why? What is the logic behind this ...
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Sulforaphane vs. Hyperthermic conditioning (sauna use) which would induce a greater heat shock response in the human body?
I’m curious to know which would induce a greater upregulation of heat shock proteins, consuming sulforaphane or putting the body through heat stress such as using the sauna.
Sulforaphane reference- ...
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Is it possible for human beings to feed through the nose?
There is a prediction on a futurology site that food can be eaten by inhalation
https://2050.earth/predictions/smell-can-feed-you
Although aerosol foods do exist they are still eaten by the mouth.
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When does the brain stem appear in humans?
This article states:
Once the neural tube closes, at around week 6 or week 7 of pregnancy,
it curves and bulges into three sections, commonly known as the
forebrain, midbrain and hindbrain. ...
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How is fructose absorbed into the body
I’m finding contradicting methods of Fructose transfer to blood
page no 264(10)One of which saYs fructose is absorbed by simple diffusion
And another sources like this say that fructose is ...
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Why is urea not converted to ammonia in the body?
After the liver processes metabolites to produce urea and other by-products, these travel in the blood to the heart, then they are oxygenated, and some travel through the renal artery to the kidneys.
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Sensory-motor pathway from visceral organs
Does anyone know is which nerves carries the transmission of sensory-motor impulses from the visceral organs? Is it splanchnic nerves?
There is conflicting evidence in the literature. On the one hand, ...
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Why do children not have the Acid Mantle?
Post puberty humans begin to secrete a substance called Sebum which changes the neutral PH of our skin from ~7 to 4.5-5.5. This has that advantage of serving as a protective line against pathogens and ...
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human body in an environment where temperature is above body temperature
What would happen if humans were to live in an environment where the temperature is above the body temperature?
Does the human body have a mechanism to cool the body?
When the surrounding ...
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Does our brain use up more ATP after smoking cannabis?
kind of an amateur here.
If the firing of the neurons' signals uses up some ATP, and smoking cannabis makes them fire off more quickly, do our brains use up more ATP to sustain that rapid firing?
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Reaction of the body to heat
In massage school we are being taught hydrotherapy -- applying cold and heat to specific areas.
It says that when applying cold, first the body goes through vasoconstriction, and then later ...
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Is there any way bicondylar/bigonial, bizygomatic or bitemporal breadth can change in adults?
Without cosmetic surgery or etc., are there any cases/example wherein a human adult has had a change in significance regarding these regions of the face? I have seen many anecdotes where people have ...
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How deep could a human swim with SCUBA apparatus?
Using normal SCUBA apparatus and wet suit, how much pressure can the human body withstand? This is assuming that they descend as gradually as necessary for their body to make adjustments. What would ...
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Contracting mouth muscles as reaction to taking in specific food items
When eating very specific food items, especially confectionery like (salty) liquorice, (it feels as if) the muscles of my mouth contract, right when it hits my tongue.
Does anyone know why this ...
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Can the heart generate its own rhythm independent to the SAN?
My textbook and a revision guide, which I believe is a reinterpretation of the textbook, state that:
The SAN initiates waves of excitation that usually override the myogenic action of the cardiac ...
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human sight at 1000x while looking into the mirror [closed]
I noticed that my eyeballs have the ability to see in what appears to be 1000x.
Setting the conditions: Look into a mirror while in a well lit room. (for me the lighting in my living room as opposed ...
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Effect of the same caloric intake of different macronutrients on body weight
To gain weight, caloric intake > caloric expenditure.
To lose weight, caloric intake < caloric expenditure.
But what is the effect of the type of macronutrient ?
That is to say :
does the same ...
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Why do our bodies maintain blood pressure but not the flow rate?
This might be a silly question but i'm not not clear
I'm always told that blood pressure is homeostatic parameter and can't not be changed but isn't what important is the flow rate to the organs? ...
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Where would vegetarians/vegans get a substitute of hemo/myoglobin from?
As far as I understand, there is a difference in the iron absorbed from meat than from other sources like grains and vegetables.
If this is the case, is it possible that not ingesting the hemoglobin ...
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High altitude rail travel
This question is primarily about human performance. I do know about hypoxia, hence this question.
I'm busy designing a fictional region, currently in the 1930's. I have a railway line that climbs to ...
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Do fat people have more chances of developing nitrogen bends?
I was reading some text on deep sea physiology. I got to know that solubility of nitrogen in fat is five times that in water. The exact text from the book animal physiology adaptation and environment ...
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Actual definition of cardiac output
Is cardiac output the amount of blood pumped by both ventricles in 1 minute or only by the left ventricle in 1 minute?
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What are the effects of oxygen toxicity in human blood?
I was reading some text on deep sea Physiology, and for to know that diving to do could cause oxygen toxicity in the blood. This was the exact text from the book Textbook of Medical Physiology by ...
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Wim Hof Method claims Alkaline Blood is Good. Contradictions? Counterproof?
The Wim Hof Method claims, that it is beneficial to have alkaline blood.
On the other site there is the medical claim that if the pH-value is not within the
range of 7.36 – 7.42, enzyms are ...
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