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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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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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What would happen if all of my skin suddenly disappeared? [on hold]

If all of the skin on my body suddenly disappeared, what would happen? By skin, I mean the epidermis, dermis, and hypodermis. What would fall out? What would happen to the deeper tissues? And ...
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Can disorders involving involuntary muscle twitches and spasms have a hypertrophic and increased residual muscle tension effect?

Meaning disorders specifically like myokymia, myoclonus (positive and negative) and fasciculations. From the section of the literature I've seen, sometimes passing mentions are made when the disorder ...
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Why different people have different Sympathetic reaction

We all know that sympathetic mechanism is similiar in humans . Why people react differently for example one may ran after seeing a lion while other may keep standing or may shout without escaping ?
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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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Are the different frequencies of Wifi differently harmful?

Assuming that WiFi IS harmfull (which is a very controverse theory, I know) is there any diffrence in the harmfullness of 2.4 Ghz compared to 5 Ghz for humans?
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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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41 views

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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1answer
36 views

How do you feed a starving person in a way that won't kill them?

AFAIK people that suffer from severe starvation (e.g., prisoners liberated from concentration camps in the end of WW2) can die if you allow them to eat "at will". If you don't have access to medical ...
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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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Pulse Oximetry, what significance does a decimal place hold?

I work in a sleep research lab. We have a couple of Masimo pulse oximeters that report pulse oximetry values in terms of integers (e.g. 90, 91, 92, etc.). Now our principle investigators used to use ...
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67 views

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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45 views

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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114 views

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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101 views

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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22 views

Do the normal in vivo spatial growth controls, not apply to hair follicles?

The common changes in hair growth are linked to changes in the size enlarging anagen follicles achieve. According to the accepted science in tissue physiology, the in vivo growth of the anagen ...
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58 views

Which major salivary gland secretes maximum amount of salivary amylase and which one secretes maximum amount of Saliva

Actually I was studying about digestion and got this confusion about which gland(Parotid or Sub-mandibulary) secretes maximum amount of saliva and which one maximum amount of Salivary Amylase. Also,...
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49 views

Is there any evidence that Vitamin K-2 megadoses increase bicondylar, bizygomatic or bitemporal breadth in humans?

Can megadosing or supraphysiological dosing of Vitamin K2 (MK4; Menatetrenone) over prolonged periods of time cause an adult's bicondylar breadth, bizygomatic breadth or bitemporal breadth to grow ...
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How is the “sampling time” of the human visual system influenced by things like hormones, metabolism, or our circadian rhythm?

For example people experience time passing slower when they are in a adrenalin rush. What is the mechanism behind it, and where can I read more about it ?
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Plasmatic anion gap or chloremia?

Since high anion gap metabolic acidosis is characterized by normal blood chloride levels and normal anion gap metabolic acidosis is characterized by elevated blood chloride levels, why it is necessary ...
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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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What is the optimal time to implant embryo in uterus for in vitro fertilization?

What is the best time to implant an embryo in the uterus. I was under the impression that the earlier the better and more natural, but also if you wait until the blastocyst age, it may be better 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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45 views

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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59 views

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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2answers
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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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What type of movement is “spontaneous movement” if it isnt reflex movement and it isnt purposive movement?

According to Spontaneous and induced fetal activity Spontaneous motor activity of the foetus depends significantly ot the foetal age; during the period between the 12th and 16th week it was ...
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What is meant with “the chest wall and lungs are coupled together”?

Since the lung and chest are elastic, we can represent them with springs. Under normal conditions, they are coupled together: the “lung” springs are stretched and the “chest” springs are compressed. ...
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Why is the resting membrane potential of excitable tissue not affected by the extracellular sodium concentration?

I know that the resting membrane potential for excitable tissue (eg, nerve) is primarily determined by the electronegative difference between the inside and the outside of the membrane for potassium ...
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41 views

How efficiently does the human body convert the energy stored in fat into kinetic energy?

I read that one gram fat contains 9 kcal energy. There are many tables around claiming that x type of exercise for t duration ...
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51 views

Is there any evidence of causation for breathing rate to affect blood pressure in a human?

I did some research and trials, and with 5 trials for a normal heart rate and 5 done 45 seconds into breath holding, the results came back showing that my heart rate of 116/65 mmHg increased to 138/90 ...
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1answer
44 views

Can some colours be processed faster/more accurately than others?

Is the human visual / motor system able to track, and move in response to, objects of certain colours more quickly and reliably than for others? By more reliably, I mean with greater accuracy in ...
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Why do I feel nauseous at the sight of blood, despite not being afraid of it?

Every time I ask google this question, all it spits at me is info on blood phobias ^-^; basically, I've always been hugely interested in morbid stuff, but I noticed that I always feel sick when ...
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Why does eating saturated fat increase blood cholesterol?

I am interested in the biochemistry of diet and the way we have been advised to eat for the past forty years. In researching an explanation for the relationship between dietary fat and blood ...
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What is the evolutionary advantage of getting hard nipples when being aroused? Why can they even be stimulated sexually?

I try to understand the evolutionary advantages of the body reactions of nipples and penises/vaginas. I'm confused, because I can explain the evolutionary advantage in a logical & consistent way ...
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What is (are) the medium of conduction for an electrical current with an external source in the human body?

I am trying to get some background for some personal research I am doing into the effects of Electro Convulsive Therapy. I don't understand how electric current from an external household source, say, ...