Questions tagged [human-physiology]
For questions on the biochemical, physical, and mechanical functioning of humans in good health including their organs and cells.
345
questions
-2
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1answer
27 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 ...
1
vote
1answer
37 views
why only Donor's antigen is seen during 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 ...
-3
votes
1answer
32 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 ...
0
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0answers
31 views
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 ...
2
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0answers
28 views
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, ...
4
votes
1answer
35 views
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 ...
0
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2answers
153 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 ...
1
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0answers
14 views
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 ...
0
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1answer
64 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 ...
0
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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 ...
1
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1answer
79 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 ...
0
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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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1answer
66 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) ...
0
votes
1answer
43 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 ...
1
vote
1answer
128 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, ...
0
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3answers
85 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, ...
4
votes
0answers
28 views
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, ...
0
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2answers
87 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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0answers
30 views
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?
-3
votes
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 ...
-1
votes
1answer
44 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 ...
2
votes
0answers
32 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 ...
0
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0answers
14 views
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 ...
1
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1answer
53 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 ...
2
votes
1answer
56 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 ...
2
votes
0answers
31 views
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....
3
votes
1answer
41 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 ...
0
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0answers
62 views
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)...
2
votes
2answers
91 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. ...
2
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0answers
53 views
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 ...
2
votes
1answer
147 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 "...
0
votes
1answer
105 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 ...
0
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0answers
12 views
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 ...
0
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0answers
23 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 ...
10
votes
0answers
107 views
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 ...
0
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0answers
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 ...
4
votes
1answer
58 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 ...
1
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1answer
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 ...
0
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0answers
25 views
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 ...
0
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0answers
19 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 ...
0
votes
1answer
39 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 ...
1
vote
1answer
65 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 ...
2
votes
1answer
39 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 ...
0
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0answers
26 views
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.
...
-1
votes
1answer
72 views
Do pinhole glasses help reduce eye strain?
I've noticed that I can read about 10x longer at screens and books without my eyes tiring using the "pinhole trick" - where you curl your fingers and look through the hole (great explanation here ...
1
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0answers
180 views
Why do arteries have a small lumen? [closed]
My biology textbook says that arteries have a small lumen relative to the thickness of their walls. I understand why they need thick walls, to withstand high pressure and stretch etc. But when ...
1
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0answers
25 views
Why don't we dribble tears through our nose?
Basal tears are tears produced by the lacrimal gland and they lubricate the eye. They are then funneled into the lacrimal sac and then from there into the nose eventually.
If this is the case, why ...
3
votes
0answers
33 views
Why does it take so long to bleed after accidentally cutting yourself?
Sorry if this is not a good site to ask this question, but I recently accidentally cut myself while chopping onions (very minor, no serious harm done), and noticed that it took quite a while before ...
1
vote
1answer
65 views
By what physiological mechanism do we not feel microbes (bacteria, etc.) living on our skin?
Background
I know our bodies have a handful of ways to threshold our awareness of sensory stimuli:
Neural density
Sensory acuity
I assume really tiny stimuli could fit between receptors
e.g., ...
1
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0answers
12 views
Why and how do red bone marrow concentrations in humans change during traditional aging?
I have found several pictures that suggest this is the case. As for peer reviewed papers I've found plenty of papers hypothesizing and testing as to the why of changes in populations of HSCs, a few ...
