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

0
votes
0answers
36 views

How to predict the position of the femoral head center given surface anthropometric data?

Given surface measurements such as hip breadth and hip depth, how would you predict the location of the femoral head center?
1
vote
1answer
141 views

Breathing in and out

I was reading my textbook and it says that breathing involves inhaling and exhaling but it doesn't say whether they happen simultaneously or sequentially. Also is my overall understanding of ...
1
vote
1answer
75 views

How suddenly does lactose-intolerance onset?

How quickly can the loss of lactose tolerance onset in an adult? Such as being able to process lactose normally to having notice symptoms associated with the inability to process lactose. I am not ...
0
votes
0answers
20 views

Why do our limbs and other body parts get numb/feelingless and then they start to tickle? [duplicate]

Why do our limbs (legs, arms) get numb/feelingless when they are under prolonged pressure or when one has crossed his/her leg while sitting for a long period? After we move it to a more relaxed or ...
0
votes
0answers
48 views
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 ...
2
votes
2answers
79 views

Are B Cells unique to an individual's immune system?

I was wondering how the body "remembers" viruses after having once overcome them, and while reading this article on the immune system (page 14, Vaccinations), I read: There are many diseases that, ...
4
votes
1answer
4k views

How does prolonged exposure to high frequency noise affect hearing?

Is there any research showing how prolonged exposure to background noises, particularly high frequency noises, affect hearing abilities? Does constant high pitched noise cause damage even a low ...
3
votes
1answer
279 views

Why apes started to contemplate and become altruistic? [closed]

I was asking this first on philosophy forums, but it is suggested, that answer could be found from evolutionary view of point, so here we go: Again my question raised when thinking of myths, their ...
38
votes
5answers
1k views

Human perception of time depending on age

From what I can tell and what thus far all people with whom I discussed this subject confirmed is that time appears to "accelerate" as we age. Digging a little, most explanations I found basically ...
22
votes
1answer
577 views

Extremely rare occurence of Heart cancer?

The occurrence of Heart cancer (similar, but not the same as Rhabdomyosarcoma) is extremely rare, about 1 per year according to MayoClinic. The reason for this rarity is explained to be the ...
1
vote
1answer
85 views

What stops the coagulation process?

Whenever there are minor/major injury to blood vessels, the platelets, fibrin, thrombin, etc. are recruited. They then seal the wound and block bleeding. What tells them that their job is done?
1
vote
0answers
62 views

Why does the ovum prefers to be arrested at metaphase 2 of meosis before fertilization? What is the possible advantage of this process?

Why does the human ovum prefers to be arrested at metaphase 2 of meosis before fertilization? What is the possible advantage of this process??Please help me with it.
15
votes
1answer
1k views

Why does looking at bright light trigger sneezing in some people?

Why does looking at bright light trigger sneezing in some people? Are there any recent studies that have found a cause for this Photic sneeze reflex? The Wikipedia article only references studies ...
2
votes
1answer
92 views

The arrangement of retinal cells?

The section of retina shows a layered arrangement of the various retinal cells. Starting from the inside (where the light strikes first) is the nerve fibre layer, ganglionic layer, amacrine cell ...
2
votes
1answer
109 views

When does identical twinning happen?

What is the window during which division into twins is possible (for instance can it still happen after implantation in the uterus)? Is one twin the "original" and the other its clone?
0
votes
1answer
103 views

Current human behavior as a genetic heritage

People: I have doubts about genetic heritage, but let me explain the context which has shown up this doubt for you: I was debating about sexism and the following question were put on the discussion: ...
0
votes
1answer
1k views

Structure of adenoids

I am not sure this question belongs in biology, but I can't find a more suitable stack exchange site, feel free to delete it if this doesn't fit here. Also, this question is going to be slightly ...
2
votes
1answer
162 views

Are inflammation and anxiety connected?

I've been reading a curious paper about the use of cannabis, and one of the passages piqued my interest: There’s also been a lot of work done on another constituent of marijuana, cannabinoid, ...
5
votes
2answers
68 views

Standard Classification of Disease

I am working on a project for health center. It involves the creation of a database of all diseases. Currently I want to classify disease on the base of their category based on international standard. ...
3
votes
0answers
51 views

Database of Medical Assertions

Can anyone point me toward a computationally-accessible database of medical assertions? I'm looking for something where each row in the database contains a single unit of knowledge. It could either be ...
3
votes
2answers
212 views

Why do our eyes “wrap” hue from UV to IR?

On the high-wavelength side of things, we see almost-infrared as reddish, with a slight tinge of magenta. On the low side, we see violet fading into the same magenta color. Why is that? You can see ...
1
vote
1answer
91 views

Death because of no radio waves [closed]

I read somewhere that a man dies if he is isolated from natural electromagnetic fields and waves. (I imply fields of radio frequencies and below.) Is it true?
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?
3
votes
3answers
121 views

Can humans be printed?

Is it possible to spray stem cells on fully grown skeleton to get fully grown humans? Currently, just read about recent advances, and wondered if something like this is possible.
0
votes
1answer
349 views

Static in limbs

I have noticed that while sitting in the Sukhasan posture(picture below) for a long time, my feet suddenly become all stiff and i am unable to move it. What I deduce from the experience is that it is ...
22
votes
4answers
10k views

How many genes do we share with our mother?

Somewhere I have read we share more than 99% of our genes with every other other person and 98% of our genes with chimpanzees. What does this mean? Don't we share 50% of our genes with our mother and ...
1
vote
1answer
124 views

How is deviated nasal septum related to cold

I have a deviated nasal septum and I always suffer from common cold I was just wondering how a deviated nasal septum can be the cause for chronic common cold
3
votes
1answer
347 views

Is there a maximum pain threshold?

Is there a maximum threshold of pain a Human can experience, beyond which point there is no noticeable difference? I ask this question in part to better understand the definition of pain and its ...
47
votes
3answers
9k views

How does the brain's energy consumption depend on mental activity?

What is the impact of mental activity on the energy consumption of the human brain? I am most interested in intellectually demanding tasks (e.g., chess matches, solving a puzzle, taking a difficult ...
5
votes
1answer
547 views

Could alcohol be used as an antibiotic?

I was thinking about how alcohol is used to sterilize, and I was wondering if it would be possible to use alcohol as an antibiotic? if it kills bacteria, couldn't (conceivably) alcohol in the ...
0
votes
1answer
2k views

For the human head, which direction is anterior, and which direction is ventral?

I read the wikipedia entry and I am sort of confused. In dog, the nose is toward the front. That's anterior. So I conclude that human nose is anterior. In dog, the head is on the back. So that's ...
3
votes
2answers
150 views

How far into a pregnancy is it before visible signs of it is apparent and risk of physical trauma increases

I'm doing research for a series I'm writing. in it the main character is pregnant however goes off to fight a criminal organization who have been killing her friends and i want her appearance to show ...
2
votes
1answer
186 views

Scrotal temperature and vascularization

The testes (at least in human males) are vascular organs, the vascularization extending even o the interstitial spaces of the seminiferous tubules. The function of the scrotal sac, is to isolate the ...
1
vote
1answer
87 views

Body's decomposition

Does a human body decompose in a completely sterile environment ? If yes, what decomposes it ? And how fast ? What happens in vacuum ? Can it remain exactly the same ? Thanks
8
votes
2answers
3k views

Preferred Aspect Ratio for Human Eyes

Our eyes are spherical, our retina is circular, but still our eyes can see more in the horizontal direction than in vertical direction. Why is it so, why is the preferred aspect ratio not square? ...
6
votes
1answer
205 views

Understanding Membrane / Resting Potential from the perspective of ions?

From wikipedia article RESTING potential: "there is no actual measurable charge excess in either side. That occurs because the effect of charge on electrochemical potential is hugely greater than ...
3
votes
2answers
5k views

Does bright environment strain eyes more than dim?

I'm trying to figure out how to modify my working conditions so that I can program longer without harming my eyes. Because doing so experimentally hasn't given conclusive results so far, I decided to ...
0
votes
1answer
74 views

Does the eye image interval refresh? [closed]

It's known the human eye takes 24 images per second. But does this refresh? For example after sleeping. Or will it always be the same interval? I talk about when the eye takes the images. So it 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 ...
6
votes
1answer
258 views

How does skin healing work?

I stacked my bike and split my head right open. About three weeks later the scab falls off and the skin is sealed over, like magic! How does it all work? How does the brain know that part of the ...
9
votes
1answer
792 views

Could humans and chimpanzees hybridize?

In some cases two species can hybridize. For example, Tigers and lions can hybridize to produce "Ligers". Would it also be possible for humans and chimpanzees (or any other species) to hybridize ? ...
6
votes
1answer
177 views

Does knowing the sex of each of a couple’s first N children have any marginal value in predicting the sex of child N+1?

Does knowing the sex of each of a couple’s first N children have any marginal value in predicting the sex of child N+1? By “marginal” I mean predictive power beyond other known effects, e.g., the race ...
21
votes
2answers
787 views

How is temperature sensed?

Can anyone summarize the mechanism by which when an object of a given temperature is placed in contact with, say, the skin on a human fingertip, the average speed of the particles of the object is ...
2
votes
1answer
985 views

Transfer of antibodies in breast milk of humans

Why isn't the IgA secreted in breast milk digested due to proteases of the digestive system in the baby? Wikipedia says: The secretory component of sIgA protects the immunoglobulin from being ...
1
vote
1answer
585 views

Transfer of antibodies from mother to fetus

My questions: When does fetus begins to acquire antibodies from mother? Does it continue throughout the pregnancy? From Wikipedia: http://en.wikipedia.org/wiki/Passive_immunity This occurs around ...
8
votes
2answers
138 views

What is the effective relatedness of inbreeding?

If a human inbreeds with a relative, how distant does the relative have to be before the homozygosity in the child is no higher than if the mate were randomly chosen from the global population?
0
votes
1answer
312 views

Why are human eye colours limited?

Related to the question What causes the colors we see in eyes?, I am wondering why human eyes are restricted in colour. Most common eye colours are blue, green and brown. Why not yellow, orange, ...
0
votes
1answer
211 views

What is meant by 73 hour birth [closed]

I was reading an article, when I read a sentence saying, His mother ... nearly died less than three years later during Mathers' 73-hour birth. What does mean by 73-hour birth?
0
votes
1answer
11k views

How reversible is decerebrate posturing caused by brain stem damage?

This is a follow-up question to How likely would Abraham Lincoln be to survive his wounds today? You don't have to see a CT scan or autopsy to know if the brainstem is injured (directly or ...