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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18 views

Vitamin B12 deficiency Megaloblastic anemic

I have two doubts regarding Megaloblastic anemia which shakes my mind (1) first is- I know that vitamin B12 is required for thymidine synthesis which is further required for DNA synthesis and so if ...
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What causes metallic tastes when you receive electric shocks

Whenever I receive small electric charges (most often by, e.g. touching the jack of a plugged in charging cable, or the casing of a charging Apple device), I experience a very distinctive taste in my ...
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why is fertilization a physico-chemical process?

I searched on the internet for the definition of a physico-chemical process. So I found that Physicochemical processes are the normal intracellular and extracellular physical and chemical processes ...
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Is it true that the cells of large and small intestines cannot secrete digestive enzymes into the GI tract in the same way as the stomach does?

When I read about the intestines, I usually see the word 'release' instead of 'secretion'. Secretions of the small intestine, for example, occur from two types of histological structures: Brunners ...
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Why does (insulin induced) hypoglycemia stimulate ADH secretion?

Intuitively, I understand that ADH (Anti Diuretic Hormone) is responsible for maintaining osmolarity, and increased serum osmolarity is a stimulatory factor for its release. (ADH increases water ...
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Is it correct that Afterload=Preload+Active tension?

Preload causes development of equal amount of passive tension which leads to distension of heart muscle. Further, afterload causes development of active tension or cross bridge formation which ...
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31 views

why are dizygotic twins genetically dissimilar

I am a high school student and I am a little confused in a topic related to dizygotic twins, I get to know that dizygotic twins are genetically dissimilar because they are formed as a result of two ...
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1answer
74 views

Why is only the donor's antigen seen during a blood transfusion?

I am a high school student and I am a little confused that why only donor's antigen matters during blood transfusion? for e.g if the donor's blood is O- so it means that it will antibodies against all ...
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1answer
33 views

Why do nerve impulses utilize potassium and sodium instead of other Group 1 metals?

Rubidium and potassium are very similar, yet the body utilizes sodium and potassium for nerve impulses. Why is this the case? Why not any other element? Likewise, why not Lithium? I've read a research ...
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Why does bicep activate during dead hang?

Hanging from a bar causes my bicep to feel much harder than when simply holding my arm straight above my head relaxed, without a bar. This was slightly surprising to me: I used to assume that since ...
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Type B Nerve fibres cause exactly what kind of autonomic sensation to the preganglionic neurons?

Ganong's Review of Medical Physiology (25th ed) presents the Erlanger and Gasser classification of mammalian Nerve Fibres as such: Type B Fibres are concerned with Preganglionic autonomic sensations, ...
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How is the renal osmotic gradient maintained even though the blood osmolarity changes?

I am a high school student and I am a little confused in 2 things related to our urinary system: We know in our kidneys a countercurrent mechanism exists due to which there is a steep gradient of ...
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157 views

How do physics notions of fluid dynamics relate to pressure gradients in circulation?

I'm having a hard time comprehending why sometimes physiology notions seem to contradict each other and contradict physics teachings. More specifically I don't understand why aortic coarctation causes ...
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Quantitative comparison of rate of energy output when burning carbs compared to fat

I'm studying scientific models of endurance exercise such as the one in a paper by Rapoport (see references below, popularization here). If I'm understanding properly, fat burning is in some sense ...
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1answer
86 views

How deep underwater could you breathe using a tube which breaks the surface until the water pressure makes it impossible to inhale air?

I'm struggling with a question asking how deep you can breathe underwater using a hollow reed before the water pressure makes it impossible to inhale. The question asked to use this data of maximal ...
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1answer
47 views

External “lungs” that process your blood the same as your real lungs do - would that stop your need for breathing?

So say your blood goes with a tube out of your body. In an external device all the chemical/biological magic would happen and it would be fed back to your body. Of course this doesn't exist (yet), but ...
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1answer
83 views

Why can we eat salty food, but can't stomach salty water?

I know that too much sodium is bad for our health. However, it struck me as odd that we like to add salt to pasta sauce or other foods we eat, yet trying to drink salt water can bring on the gag ...
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1answer
26 views

Which landmark paper first described the differentiation of T-cells?

T-cells are distinguished from B cells in part by their locus of differentiation/maturation (thymus). This is textbook knowledge, but I was wondering which particular person or people were responsible ...
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69 views

If you only ate fruits, vegetables or smoothies would you be able to skip drinking water?

If you only ate fruits, vegetables or smoothies would you be able to skip drinking water? I do not see some animals (like squirrels) drinking water daily (doesn't mean they don't have a water source) ...
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1answer
51 views

How do prodrugs exactly work? Are there multiple varieties of prodrugs?

I have been reading about a (new?) prodrug of LSD, 1CP-LSD, which is being synthesized in the body to LSD. However, I don't know how exactly. I read somewhere, that another prodrug of LSD, 1P-LSD was ...
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1answer
147 views

Does LSD “stay” in your fat storage and then “returns” back?

This rumor was told me by a very anti-drug person. A stance I agree with only lightly. The rumor was that when you take LSD, it stores itself in your fat storage, and then returns back in 3-6 months, ...
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3answers
88 views

Why aren't the twin organs like both the eyes, ears, hands and legs lying both sides of a human body identical?

Both the eyes are not identical in geometrical shape and size i.e. physical appearances of both the eyes of a person are different from each other. The same difference is observable in both the hands, ...
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How long does it take to reset sense of smell?

I have noticed that when I go on vacation for several days and then come back home, there is a distinctive, relatively mild paint smell in my apartment complex. However, under normal circumstances, ...
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2answers
101 views

Why did the indigenous peoples of northern Asia and America not evolve the same physical characteristics as people of Nordic ancestry?

I was watching DW's documentary on the Arctic the other day, and I was struck by how the indigenous peoples of the far north seemed - visually speaking - to fit into two categories. On the one hand, ...
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Why do animals yawn? What is the biology behind it? [duplicate]

We yawn whenever we are tired and body needs rest. Why does the mouth open wide and a large volume of oxygen is inhaled?
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1answer
53 views

What is the duration between: the moment we stop breathing and to body's and involuntary mucle movement? [closed]

I studied that if someone stops breathing by pressing their nostrils with fingers and start to starve without oxygen, the body will automatically cause the hands to leave the nostrils in a certain ...
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45 views

Plasmolysis and turgor pressures

I am a high school student and I am a little confused in plasmolysis, when we study plasmolysis, we say that at limiting plasmolysis, the turgor pressure OR pressure potential reduces to 0 what do we ...
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37 views

How would our vision be improved if our photoreceptors were not backwards?

I'm curious to how much better human eyesight would be if the nerves from our rods and cones were correctly placed behind the receptors? Are there any Animal Models with correctly placed ...
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Quantitative Physiology Textbooks Recommendations?

I am currently completing a 2nd year (UK) Mamamilian Physiology Module and a Neuroscience Module. However, my degree is also 40% Maths and Statistics. So in order to learn the content better, I am ...
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1answer
56 views

Why don't sodium Voltage Gated Channels open during Repolarization?

During Depolarization the Sodium VGC open when they receive the Threshold Stimulus. But when Repolarization occurs there comes a point when the cell interior has exactly the the same potential that it ...
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1answer
66 views

Is Pars intermedia functional in humans?

My textbook says, "Pars intermedia secretes only one hormone called melanocyte stimulating hormone (MSH)." My teacher says that in humans MSH is secreted by the anterior lobe because the ...
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How to estimate oxygen consumption of an average human during different activities?

I've tried to find some resource on the internet but had little luck. I'm looking to see if there's any data on average oxygen consumption of average to well trained humans during different activities....
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1answer
42 views

Concept of mean systemic filling pressure

Mean circulatory filling pressure (MCFP) in humans was defined by Guyton as "the pressure that would be measured at all points in the entiere circulatory system if the heart were stopped suddenly ...
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What is “KK1 enzyme”?

In the book "The Kaizen Way" by Robert Maurer, I've read the following: When we’re sitting, our muscles go into a form of hibernation, causing our bodies to shut down the enzyme (called KK1)...
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2answers
109 views

Is water movement across cell membrane purely diffusive or it always requires channels?

If we see nephrons, in the descending part of Loop of Henle (LoH), water movement is allowed but solute movement is not. On the contrary, in ascending LoH, solute movement is allowed but not water. ...
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What is the function of human Trypsin Inhibitor if trypsin is secreted in the inactive form of Trypsinogen? [closed]

I was reading about pancreatic digestive enzymes in a Textbook of Medical Physiology and I came across Trypsin Inhibitor. The text stated that: It is important that the proteolytic enzymes of the ...
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1answer
173 views

Why does exhaled air still contain oxygen?

I am a high school student and I am a little confused in the concept of breathing: My confusion is that, when we talk of exchange of gases we say that gases always diffuse from their high "...
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1answer
111 views

Why does this oxygen duration chart have increased times above 30,000 FT MSL?

This oxygen duration chart from an airplane shows the amount of time a pilot can be on oxygen at a specified altitude (in 1000s of feet). For example, the chart shows two pilots able to cruise at a ...
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Using serotonin for relief from allergies

When someone suffers from an allergy, due some allergens they are given drugs like anti-histamine, adrenaline or serotonin. How does serotonin affects the body to give a relieve from the action of ...
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25 views

How does mannitol decrease intracranial pressure?

What is the mechanism by which mannitol is able to reduce intracranial pressure? Also why aren't other substances used for this purpose such as say sorbitol (an epimer) or in fact any other ...
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How do the biophysics of how cerebrospinal fluid mechanically protects the brain work?

The two mechanisms I've seen mentioned are the cerebrospinal fluid (CSF) acting as a hydraulic cushion or shock absorber, and how CSF creates a micro-gravity environment through buoyancy. I have very ...
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17 views

Why does glomerular filtration result in a filtrate with the same osmolality as plasma?

Unlike the plasma, the ultrafiltrate has no proteins which are prevented from filtering out. Shouldn't the loss of these proteins result in a loss of oncotic pressure and thus a different overall ...
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1answer
80 views

Why do beta-1 and beta-2 adrenergic receptors result in two completely different effects (though both use Gs pathway)?

$\beta_2$ adrenergic Receptors are $G_s$-coupled 7-TM proteins. Considering that $G_s$ , by activation increases $[\text{cAMP}]_\text{cytosol}$ which inhibits MLCK of smooth muscles (and causes ...
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24 views

Why severely increased Ligand (eg Hormones) concentration downregulates the Receptor?

As an example continuous high blood level of GnRH in humans causes a suppression of LH and FSH. This is due to the fact that increased GnRH downregulates GnRH-Receptors . My question is how this is ...
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Can severe vasoconstriction increase systolic blood pressure?

I know that, vasoconstriction results in increased total peripheral resistance which is responsible for the rise in diastolic blood pressure. Also, cardiac output is responsible for the systolic blood ...
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20 views

Topography of motor deficit and spasticity in UMNS

As a medical student, I have been told that upper motor neurone syndrome is a cause of motor deficit and spasticity. The motor deficit is said to be affecting predominantly the extensor apparatus at ...
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47 views

How does noradrenaline result in rise of systolic blood pressure even when the cardiac output is decreasing?

Systolic blood pressure[SBP] depends on the cardiac output. When Nor adrenaline is given there is vasoconstriction due to alpha-1 action on blood vessel, vasoconstriction results in increased total ...
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1answer
72 views

Partial pressures of different gas in human blood and how they are calculated?

In Respiratory Physiology, we use the $P_x{O_2}$ and $P_x{CO_2}$ in blood at different regions of the peripheral circulation. From my Chemistry knowledge I know that $P_x$ of a gas in a solution is ...
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1answer
40 views

Are intestinal and pancreatic lipases different?

For explaining the action pancreatic lipase, my book wrote this equation:- $$fat\space particles + lipase\rightarrow fatty\space acid + glycerol + lipase$$ But for intestinal lipase, my book has a ...
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Under which conditions is human energy consumption minimized?

Including but not limited to: body state consumed food composition state of the digestive tract diseases wounds sleep coma, etc.; death excluded environment state temperature light pressure, etc. ...

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