This tag is for questions about the general biological features of human beings (as opposed to the biology of non-humans).

learn more… | top users | synonyms

2
votes
1answer
180 views

Can antibodies be formed against white blood cells after blood transfusion?

If antibodies are produced against other blood groups' red blood cells, why can't antibodies form against white blood cells, of any blood group? (even the same one, as MHC will be different in almost ...
2
votes
1answer
1k views

Ammonia smell after physical exercise? What is the explanation? [duplicate]

After exercising vigorously one can sometimes smell ammonia and it feels like it's coming from within the nose actually. There is no indication that others can smell it when I do (i.e. seems to be ...
3
votes
3answers
235 views

Blood pressure during exercise

What happens to blood pressure when we exercise? Does it increase, decrease, or remain the same? If it does increase, why are patients with high blood pressure recommended to exercise?
4
votes
1answer
358 views

Would a spinal injury decrease human height?

A woman I know has been losing height at a rate of few cm a year following a severe spinal injury. How is this possible? What kind of injury could cause such progressive loss of height? Could this be ...
3
votes
2answers
1k views

Ill effects of urea and NH₃ on metabolism

What exactly does urea do that harms our body? Does it interfere with our cellular processes or disturbs the colloidal onchotic pressure of our blood? I have heard that NH3 damages the brain. What ...
1
vote
1answer
115 views

copper spiral birth control not toxic?

I Always thought that copper was toxic to the human body. So how can it be safe to place a copper object (birth control spiral) into a uterus for a duration of 5 years?
2
votes
0answers
54 views

How to use mechanical microstrainer to extract tissue proteins from human? [closed]

Background: There are many methods to extract proteins form human tissues out there. The majority of them use an extraction buffer containing variable concentrations of detergents and protease ...
5
votes
1answer
177 views

What effect do oligosaccharides, like those found in legumes, have on the composition of intestinal flora in humans and if so how so?

I know that intestinal flora metabolising oligosaccharides, like those found in legumes, is the cause for the well known fact that legumes cause flatulence, but does an oligosaccharide-rich intestine ...
8
votes
1answer
761 views

Why does it hurt more when you touch a nerve directly?

I am not a biologist nor know much about biology (so please explain in layman's terms) however I have always been curious as to why this is. What causes the difference in pain between touching an ...
10
votes
3answers
1k views

How are our senses dimmed during sleep?

Our senses are not as sensitive during sleep compared to wake. There is an arousal threshold during sleep that only when it is overcome will it wake a person up. My question is how is this arousal ...
2
votes
1answer
500 views

Why is the blood pressure in the superior vena cava during inhalation less than during the exhalation? [closed]

For further investigation into the progress of the blood pressure, we will measure a patient's blood pressure in the superior vena cava measured during inhalation and during an exhalation. His heart ...
2
votes
1answer
106 views

Is RGB diode lighting okay for the eyes?

Is a light source giving off light composed of red, green and blue lights harmful to the eyes? Does it lack any important qualities that other artificial light sources, such incandescent lamps or ...
10
votes
2answers
2k views

What is the evolutionary reason behind the fragility of teeth?

Almost all organs in the human body have a rather large threshold within which the organ or tissue is capable of repairing itself using materials supplied by the body, whether it's made from organic ...
5
votes
1answer
483 views

What could account for an apparent loss of mass at death?

An interesting tidbit floating around the internet these days is that Dr. Duncan MacDougall apparently weighed people shortly before and after death, and found an average of a 21 gram discrepancy, to ...
5
votes
4answers
48k views

How long human can survive with just drinking water everyday

Can humans live without eating food, just by drinking water? How long can we survive just by drinking water everyday?
6
votes
4answers
9k views

How long can a naked human survive on Mars?

How long can a naked human survive at the surface of the Mars planet? For instance, let's say a worker's base takes fire while he sleeps, and he has to run to the emergency building 200 meters away ...
1
vote
1answer
47 views

I'd like to know the name and a few details of a certain time-keeping structure in the human brain

I once heard of this structure on the Discovery Science channel and have since forgotten the name. The details I remember about it were that it is the central time-keeping device for the brain located ...
5
votes
1answer
154 views

Do lunar rhythms have impact on human biology, if so, how?

I'm approaching this question from the circadian rhythm perspective. A circadian rhythm is a 24 hour cycle. While doing research on deep sea circadian rhythms, I found this abstract which seemed to ...
8
votes
1answer
74 views

What processes are responsible for focusing on an image only seen by one of the eyes?

When a person is spying from around a corner with only one eye, it's rather easy to ignore the other eye's image, since it's probably much darker, because one usually spies around a corner standing ...
2
votes
1answer
146 views

Is there a comprehensive list of human circadian-like processes, hormones or gene expressions?

I'm reading this article onblood sugar and circadian rhythms and the following question popped into my head: a lot of articles mention various diurnal or circadian rhythmicity of biological processes. ...
2
votes
3answers
3k views

What organs are absolutely needed by the human body?

The title is my question: what organs are absolutely needed (fatal if injured/removed) by the human body and perhaps animals in general? I'm not asking which organs are mechanically replaceable, but ...
0
votes
1answer
129 views

Could a person become physically transgender through artificial means?

Let's say there's a girl who carries a few masculine traits not normal in most girls, such as a high level of testosterone; we know there are countless reasons why something like this could happen, ...
-3
votes
1answer
471 views

What are the long-term negative effects of going without water/food for a period of time [closed]

There are no good answers anywhere. so asking: this is not about days of survival without water. This is about long-term negative effects induced from not drinking water for at least the mentioned ...
2
votes
1answer
74 views

Why it is so difficult to treat leukemia?

I want to ask what is the reason that T315I type CML leukemia is currently untreatable. I have read quite a few papers in this subject. Why the current genetic oriented engineering drugs failed to ...
2
votes
1answer
136 views

Why do ion concentrations change with different secretion rates in pancreatic juice?

Why is it that when secretory rate increases in the pancreas the concentration of chloride ions decreases, and the concentration of bicarbonate increases in the production of isotonic NaCl secretion? ...
2
votes
2answers
349 views

What mechanism suppresses melatonin release in humans?

I'm looking at melanopsin, a photo pigment in the human eye. One of its actions is to trigger suprachiasmatic nuclei SCN to suppress melatonin release. I'm interested in learning what is the exact ...
2
votes
2answers
349 views

How to know if a woman is fertile without actually making her pregnant?

How to know if a human female is fertile (can give birth to child in future) without making her pregnant? Any signs, tests?
2
votes
1answer
79 views

Whence fecal E. coli (et al.) if swallowing it is dangerous?

I don't know much about medicine, and I know even less about microbiology, but I understand that there are organisms in the lower gastrointestinal tract (and in feces) of a human, like Escherichia ...
2
votes
1answer
2k views

What would be the best design for spike-and-recovery and linearity-of-dilution validation experiments in one 96-well ELISA plate?

I have searched in the web for a detailed explanation of doing such validation experiment, but unfortunately couldn't find a satisfactory one. I came across the following sources: Thermo ...
3
votes
0answers
101 views

How do omega-3 fatty acids reduce cholesterol at the molecular level?

I have heard that omega-3 fatty acids found in fish are a good way to prevent/reduce cholesterol problems. My question is how do omega-3 fatty acids do that: what are they doing on a chemical level ...
0
votes
1answer
31 views

Is there any relation between weight class and extreme lifting performance in O-lifting?

We usually thought that weightlifting is a tough game. It is only for great physique. There are 6 man in history who lifted 3 times their body weight. Check here. 3 of them are Bantamweight(56kg), ...
3
votes
1answer
222 views

Perception of distant lights without glasses

I am fairly short-sighted and wear glasses pretty much all the time. Naively, I would expect that when I take my glasses off, the image I see should look very much the same as as a photograph that's ...
6
votes
2answers
5k views

Why does plucking nose hair cause tears in the eyes?

It's not a particularly sad or painful thing to pluck a few nose hairs, but it's common for the tear ducts to wet up when doing this. I would like to know the physiological reason for the ...
6
votes
2answers
21k views

What could cause hairs to gray at the tips but not the roots?

I have noticed that some of my sporadic gray hairs are gray at the tip side but oddly, not near the roots. Some are even only gray in the middle. I find all of this very counter intuitive, and I ...
2
votes
1answer
552 views

What controls the breast size?

I am not a biology student, just a curious person. To be specific, I'm talking about humans and specifically about females. I know that it might apply to other mammals. What controls the size of ...
1
vote
1answer
95 views

Is there an optimal illumination level for human habitats/workplaces?

I know of melanopsin, a photo pigment in mammal eye that helps regulate circadian rhythms. It responds most strongly to blue spectrum light. There have been experiments that demonstrated that ...
9
votes
3answers
5k views

Why can all animals swim in water without learning to swim but humans cannot?

I had a question since I was a child. I was always curious about the fact that all animals can swim in water. They don't need any training or to learn swimming. But humans need to learn to swim. Why ? ...
2
votes
1answer
71 views

Are (baseline) high blood levels of melatonin associated with either circadian rhythm or mood disorders?

(Exogenous) melatonin is administered at night for treatment of circadian rhythm disorders, but melatonin taken during the day is linked with depression. I would like to know if high blood levels of ...
1
vote
1answer
798 views

Relation between goose bumps and temperature

As we all know, cold weather will cause us to have goose bumps. I honestly don't know why (1), because our skin contracts? Apart from that something quite contradicting happened this morning. I was ...
2
votes
2answers
151 views

Agony, Hydrophobia and viruses in the light of evolutionary principles

I'm undergraduate physics student, but I've always been interested in biology. So I have a couple of questions about an application of the evolutionary principles to practice. Agony as the last ...
7
votes
2answers
481 views

In humans what is the last metabolic process to cease after death?

After death which of our body's metabolic processes will continue functioning for the longest?
1
vote
1answer
206 views

Are there any viruses or bacteria which have evolved to withstand higher temperatures due to fever

My question was raised after receiving this information: The primary reason the body raises its temperature (via the Hypothalamus in this case) is that bacteria and viruses tend to optimally ...
5
votes
1answer
773 views

If fever is a natural immune defense, why do people take drugs to lower it?

If fever is a natural defense against pathogens, why do sick people take NSAIDs to reduce the fever?
-3
votes
1answer
151 views

How much can be said about behaviour (future) based on bloodgroup?

My bloodgroup for example is A+. How much information is knowing my bloodgroup? How much information can be known from a blood sample? I expect you to be able to clone if known a complete DNA sequence ...
5
votes
1answer
106 views

Can cirrhosis be caused by physical compression of the body?

On a random forum, a member speculated that their cirrhosis was caused by wearing tight-fitting clothing such as a girdle or corset. This leads me to the following question: Question: Can ...
4
votes
1answer
4k views

Why do sneezes come in pairs or more?

I very rarely sneeze just once, usually there's two coming in a row, and I've noticed the same thing in other people and even in animals. Is there any reason for this?
4
votes
0answers
42 views

Can a sound frequency 'not' within human hearing (20 Hz - 20 kHz) damage hearing when it is of high volume? [duplicate]

We can't hear sounds outside the range of 20 Hz - 20 kHz. However, if an inaudible sound is played at high volume, will one's hearing be affected?
1
vote
1answer
95 views

What in soy are people allergic to and will these allergens be passed along if an animal that has eaten soy is consumed?

I have two related questions about soy allergies and possible reactions. What is it that are humans who have soy allergies actually allergic to? What is the allergen? If an animal eats soy, are ...
11
votes
1answer
102k views

What causes random long white body hairs?

I'm sure many of you have experienced this - you scratch your back or brush your hand over your arm and find a ridiculously long thin white hair, sometimes as long as 3 or 4 inches. I know a few ...
1
vote
1answer
76 views

Are there any studies of epigenetic difference between twins during their lifespan?

Are there any studies of epigenetic difference between twins during their lifespan ? I ask because I wonder if there exist phases during lifespan, when environmental factors plays major role ...