Questions tagged [human-physiology]
For questions on the biochemical, physical, and mechanical functioning of humans in good health including their organs and cells.
299
questions
0
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1answer
49 views
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, ...
0
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0answers
18 views
What is the purpose of descending auditory signals from the brain?
What might the purpose be of the brain having descending auditory signals from the brain? My textbook is very vague about this and I am just curious.
1
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0answers
18 views
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 ...
0
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0answers
14 views
Adipose Cellularity and Energy Intake
Is it plausible to consider increasing adipocyte size as a causal factor predicting less energy intake in humans in conditions of energy balance. It is well known that higher fat mass (FM) predicts ...
-2
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1answer
38 views
What are the genetic basis for further classification of human beings? [closed]
According to anthropology, human race further gets divided in Caucasians, Mongoloids, Aboriginals, Eskimos, Red Indidians and Negro's. How far, is this classification, though maybe anthropologically ...
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0answers
54 views
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 ...
1
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2answers
56 views
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 ...
0
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0answers
17 views
What is the effect of lesion of dorsal nerve root?
Dorsal nerve root or dorsal horn of the spinal cord is sensory in nature. The primary afferent neuron or secondary afferent neuron ascend via the dorsal horn of the spinal cord to form the reflex arc ...
1
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1answer
60 views
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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1answer
47 views
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?
4
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0answers
42 views
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 ...
0
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0answers
8 views
Using EMG to measure increases in strength
I have a DIY EMG kit and I know it can be used to measure muscle activation. I am wondering, is there a relationship between muscle strength and the value obtained from the EMG sensors measuring on ...
0
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0answers
28 views
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, ...
2
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1answer
40 views
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 ...
0
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0answers
26 views
Biochemistry of pleasure of/desire for physical exercise in mammalians and humans?
Are there some known biochemical mechanisms, that induces desire for/pleasure of physical exercise in mammalians and humans? I have heard, that horses can not live without physical exercise and they ...
1
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0answers
48 views
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 ...
0
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0answers
28 views
For how long can the heart be in asystole and then restart itself?
The medication Adenosine is used for the treatment of some abnormal heart rhythms. However, according to Wikipedia, it can cause asystole for a few seconds:
Because of the effects of adenosine on ...
0
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0answers
20 views
Do tendons thickened due to a tendon injury/pathology have the same strength as “normal” tendons?
I read in this 2015 study {1}:
This study
is the first to show that pathological tendons have sufficient levels of aligned fibrillar structure. Pathological
tendons may compensate for areas of ...
2
votes
1answer
60 views
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 ...
1
vote
1answer
87 views
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 ...
0
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1answer
82 views
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 ...
0
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0answers
116 views
What is the significance of different types of papillae present on tongue?
Fungiform, Circumvallate, Filiform, Foliate Papillae are present on the surface of the tongue. They have a role in increasing surface area for taste buds that can be accommodated on the tongue. Each ...
1
vote
1answer
260 views
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 ...
1
vote
1answer
66 views
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 ...
2
votes
2answers
64 views
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 ...
0
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2answers
73 views
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?
0
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1answer
124 views
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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12 views
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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0answers
27 views
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 ?
0
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1answer
68 views
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 ...
1
vote
1answer
33 views
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 ...
2
votes
1answer
94 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 ?
7
votes
1answer
820 views
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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0answers
27 views
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 ...
0
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0answers
58 views
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- ...
0
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1answer
74 views
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.
...
4
votes
1answer
138 views
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. ...
2
votes
1answer
45 views
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 ...
4
votes
2answers
201 views
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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0answers
25 views
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 ...
5
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0answers
91 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 ...
1
vote
1answer
52 views
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 ...
0
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0answers
74 views
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?
3
votes
2answers
87 views
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 ...
-1
votes
1answer
128 views
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 ...
1
vote
1answer
58 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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0answers
12 views
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 ...
4
votes
1answer
122 views
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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0answers
39 views
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 ...
2
votes
1answer
32 views
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 ...
