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

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What is the biological basis of “energy” that extraverted humans draw from social engagements and introverts expend?

This question is related to this question about introverts becoming exhausted after extended social events on cognitive sciences stack exchange. As I read more on the topic of human ...
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0answers
55 views

What proportion of salt in water would make it not dehydrate nor hydrate someone?

Drinking sea water can be deadly as it contains too much salt, basically de-hydrating the body. Normal tap water contains little salt and is good for re-hydration. My question: How much salt needs to ...
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2answers
442 views

If human eyes watch an area, what's the shape of its capturing shape? Rectangular? Half spherical?

A normal camera can capture a rectangular image. If human eyes watch an area, what's the shape of the captured region? Rectangular? Half-spherical?
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0answers
63 views

How does proximal centriole of human sperm function?

I've read that the human's unfertilized oocyte ( stuck at metaphase 2 of meiosis ) lacks centrioles and that it completes meiosis 2 after fertilization as sperm gives its proximal centriole. Then what ...
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1answer
213 views

Evolutionary reasons why you cannot tickle yourself but masturbate

There are obviously good reasons that explain why you cannot tickle yourself (see e.g. here). This got me thinking why it is possible to masturbate... Wouldn't it make more sense to not being able to ...
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1answer
42 views

How does the body really react to exposure to the vacuum of space?

I've seen sci-fi movies where the effects the body being unprotected in outer space are wildly different. In one movie, a guy radios for someone who's been ejected into space to breath all the air ...
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1answer
35 views

What is 'independent assortment'?

What is the definition of 'independent assortment'. I tried researching this term but came back with two results: alleles assort themselves independently of different alleles the alignment of ...
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0answers
31 views

Why does a pacemaker have a negative pulse? [closed]

Why is the first phase of the pulse from a pacemaker cathodic?
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2answers
374 views

How hot can a beverage get without burning the tongue?

What is the maximum temperature that a beverage can be without burning the tongue? I suspect there's a maximum temperature that the surface tissue of a tongue can withstand without being damaged ...
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1answer
2k views

Why do we have five fingers?

Humans (and other humanoid mammals) have five fingers in each hand. Curious to know, why five? Wouldn't more fingers be more useful? Is there any evidence that it used to be different and natural ...
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1answer
38 views

Clarification on BMI formula

In the BMI formula= (Weight) X 703) / (Height^2) , what does 703 represent? What is a reliable source that I can cite for this answer? weight= lbs height= inches
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1answer
31 views

Does vitamin D form crystals in the blood with calcium and magnesium?

I read on a vitamin-D product (2000NE) that I should not use calcium and magnesium with it, because it can result crystal formation in the blood. I googled, but find anything about this. Is it true? ...
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2answers
51 views

How does the cell regulate different metabolic pathways?

I heard somewhere that cells use different nucleosides bound to triphosphates e.g. ATP, GTP, CTP and other modified compounds: NADH, NADPH to distinguish between different metabolic pathways and so ...
2
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2answers
55 views

Does the cellular response to every receptor work the same way?

I heard somewhere that activating any receptor results in the same intracellular response (signaling) which involves NF-κB. If that is true, I hardly understand how the cells distinguish between ...
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1answer
52 views

How to evolutionary explain menstrural cycles synchronization? [closed]

Sorry, I can not indicate the source, but I read that menstrual cycles of women who live in the same house over time sync. Is it true? How does it work?
2
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1answer
40 views

Relieving pain by massage

How come the pain in our body, primarily due to excessive physical exercises, vanishes after having a massage? What is the mechanism?
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0answers
14 views

Would constant light or fading light be registered as more wakefulness promoting by the Supra Chiasmatic Nucleus?

During the fall and winter season, a number of people are experiencing Seasonal Affective Disorder. One of the way it has traditionally been treated is with a dedicated lightbox - a very high ...
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0answers
17 views

Dawn simulation - does color change affect waking up?

just curious. Are there any works or research results related to the influence of light color used for dawn simulation? I mean those wake-up lights which try to simulate dawn to make waking up better ...
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0answers
43 views

What factors affect the likelihood of auditory stimuli causing arousal during sleep?

I've noticed that the sound of water drops makes me wake up from sleep but other more strong sounds don't make me wake up. I can't find anything about this. The only reason I can think of is maybe ...
3
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1answer
50 views

What is the most recent well-attested common ancestor of chimpanzees and humans?

Humans and chimpanzees are related and thus have a most recent common ancestor. Of course pinning down this precise point is essentially impossible, so I'm interested in close ancestors of this most ...
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0answers
16 views

Physiological function of CFTR gene product? [duplicate]

I just need a clarification. If I am to talk about the physiological function of the CFTR gene product? Then what should I do research and talk about? The only physiological function that I can ...
3
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0answers
49 views

Does eating antacid (such as Magnesia) before meal have any impact on digestion? [closed]

During an anatomy lecture I heard of the importance of the acidity of gastric acid (e.g., killing microorganisms, dissolving food, being a factor for triggering further processes). If a healthy person ...
4
votes
2answers
229 views

The gender of offspring of Twins?

Given identical twin males, Michael and Douglas, Douglas and his wife have four children, all of whom are girls. Michael and his wife have only one child, a boy, and are expecting another. What are ...
8
votes
1answer
172 views

How fast can a human run?

I'm a runner (cross country) and I'm always amazed at how fast Olympic sprinters are. There's a lot of hype about those in the 100-meter dash being the fastest in the world, and we're constantly ...
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1answer
44 views

Does repolarization of muscle fibers mean that the muscle bundle is relaxed?

If I flex my bicep and continue to contract it does it mean that the muscle cells are in depolarizing state and not repolarizing?
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1answer
25 views

How is Microenvironment strictly defined?

I started to think this definition of Wikipedia: Microenvironment (biology), a small or relatively small usually distinctly specialized and effectively isolated biophysical environment (as of ...
8
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1answer
103 views

Can a human cell live indefinetely in a controlled environment?

How long can a human cell live in a controlled environment, given all necessary nutrients, temperatures, mechanisms for waste removal, and other requirements are provided for? Put differently: Can a ...
4
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1answer
83 views

Are all functions of a human cell known? [closed]

Please bear with me as I'm intruding into your world from a computer science background. In programming, once you have created a program, you know all functions of that program. Thus, 100% knowledge ...
3
votes
1answer
258 views

Do you produce more sperm after 1 week of abstinence vs 1 year of abstinence

Question: I was wondering if the amount of sperm increase with the amount of abstinence? Side questions: Is their a max amount of sperm? What happens with the excess amount?
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1answer
45 views

Is there any research paper which identifies left and right brained behavior?

There are many web puzzle to identify, but does it really have any scientific proof? something like - http://braintest.sommer-sommer.com/en/ any logic behind it?
3
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1answer
97 views

Is the activity of enzymes in the human body affected by the outer temperature?

I have to do a research about the enzymes in the human body and the things that affect them. I know that the body temperature affects the activity of enzyemes but I'd like to know if the outer ...
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1answer
22 views

Help me understand my membrane potential assignment

Epithelial with the ability to transport NaCl is bathed in an isotonic salt solution with these values (in mM): 136 Na, 6 K, 140 Cl. The intracellular concentrations are: 45 Na, 100 K, 13 Cl. The ...
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1answer
47 views

Like size and colour constancy, why does the brain not maintain focus constancy?

I have progressive myopia. I grew up with perfectly normal eyes but slowly started getting myopic. The thing is, my brain knows (or should know) what the world looks like -- it knows that far away ...
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2answers
59 views

Can Hepatitis be caused by Bacteria?

There are many information about viral hepatitis. But it is interesting for me, can bacteria cause the hepatitis too?
2
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1answer
123 views

What are the disadvantages of forbidding flights to and from the African Ebola region?

After looking through the available Stack Exchange sites, this one seems to come closest to the appropriate place to ask... Popular opinion, including my own, is that banning flights to and from the ...
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2answers
80 views

Problems understanding membrane potential

I understand that membrane potential is the difference of the extracellular and intracellular ionic charges, due to their concentrations. We say that the extracellular space has a charge of 0 and then ...
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1answer
65 views

Understanding intra and extracelullar concentrations (membrane potential)

I have 4 question (not homework) What happens to the cells membrane potential if: a) Na+ outside rises by 40mM b) K+ inside rises by 10mM c) K+ outside rises by 10mM d) A- (impermeable ion) ...
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1answer
172 views

Why can you not tickle yourself?

It's the age old question, why can't we tickle ourselves? If you rub your fingers along your skin, sure there's sensation but you don't break down into a laughing fit (at least I don't :P), if someone ...
2
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1answer
42 views

Why can't we smell our own bad breath? [closed]

Why can't we smell our own bad breath. Is there any way we can do that?
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1answer
77 views

Is there a known glucosepane cross-link breaker?

I read the following on wikipedia: There is, however, no agent known that can break down the most common AGE, glucosepane, which appears 10 to 1,000 times more common in human tissue than any ...
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3answers
212 views

Why is it better to drink room temperature water instead of cold water? [closed]

My teacher told me that drinking water that is room temperature is better for you then drinking cold water, but she did not tell me why that is. I want to know because I often drink cold water (with ...
4
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1answer
53 views

Are some facial features more important than others in human facial recognition?

I'm often surprised by the human ability to correctly identify other individuals despite significant modifications due to ageing, hairstyle, injury etc. But, sometimes the addition of a beard and a ...
4
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1answer
35 views

How can ingesting a prion “infect” someone?

That's something that's been bugging me for a while... Our gastrointestinal tract produces proteases that degrade proteins. Prions are proteins. Shouldn't they be broken by proteases? Also, how can ...
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0answers
67 views

Can sealed epiphyseal growth plates theoretically be restored via epigenetic or genetic methods?

I know that epiphyseal growth plates seal up once people become young adults and that it is currently impossible to restore them to actively produce new bone growth but, is it theoretically possible ...
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0answers
35 views

Is Canine teeth enough evidence to prove that one is a Carnivore?

This question does not assume that we are meant to be carnivores in the first place; In fact I have no idea to which category we belong to anyway! There are several posts online indicating that ...
0
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1answer
46 views

Is the innate immune system capable of identifying all foreign antigens?

I've been studying immunology on my own lately and I would like to know if the macrophages and the other components of the innate immune system are capable of identifying all foreign antigens. As far ...
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0answers
33 views

Do animals have social status as humans in our society?

As our society and it's functioning is closely related to the ones of animals, one question arises: Do animals in nature have social status as humans? People often display it publicly, by buying nice ...
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1answer
203 views

How does electrolarynx work?

I have heard that this is an effective replacement for patients who have a dysfunctional larynx, partly due to cancer. I am curious to know the inner working of this device and why such a robotic ...
0
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1answer
33 views

Help me understand how the thyroid secretes

Please have a look at this close up light microscopic image of a thyroid gland: So I'm guessing the cubic epithelial cells surrounding this big red pulp are the secreting cells...? If so, is the ...
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4answers
162 views

How does an embryo know where to grow limbs etc

For example you have a cell or already a bunch of cells. Those cell(s) divide and after several week you have a grown organism, for example a human with limbs, several different organs etc. However, ...