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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1answer
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Exact location of E. coli in human body

E. coli lives in lower intestine. But exactly where can we find E. coli, and where is there none (or a really small amount) of it? I need the exact names of parts of the lower intestine where we can ...
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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 ...
3
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1answer
267 views

Like other animals, why humans don't have species & breeds?

Like other animals, why don't humans have species & breeds ? Even my pet dog is one type of breed, but we (humans) lack breeds & species? What is the main reason?
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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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1answer
87 views

Why do people and animals stretch out their bodies and what is causing this behaviour?

I noticed that my cat which is only 6 months old has started stretching its body from time to time. Then I thought that this motion doesn't seem very natural from another cat's viewpoint, so my cat ...
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0answers
24 views

What's the max speed that humans could run? [duplicate]

Assuming humans could use all of their muscle strength at once, with no need of cooling or energy, how fast could we theoretically run?
8
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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 ...
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1answer
41 views

Safe level of chlorine in water [closed]

Chlorine is usually mixed in water to make it safe for consumption. What is a safe quantity of chlorine that can be consumed? What are the side effects of chlorine and does this include hair loss? ...
4
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1answer
962 views

What are the advantages and disadvantages of being ambidextrous?

What are the advantages and disadvantages of being ambidextrous? We have two hands and we nearly can't use one and this seems like a weakness, and a stupid one when you first think about it. But ...
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1answer
97 views

Any relevant knowledge/studies about voluntary goose bumps [duplicate]

I'm not entirely sure how normal this is, but since I was a child, I've been able to produce myself voluntarily a "chill" sensation that seems to start on my head and traverse the rest of my body, ...
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6answers
3k views

What is the use of eye banks, if eyeball transplants do not exist at present?

Corneas are donated and transplanted, but not the eyeball. I don't understand. What is the purpose of donating a cornea without an eyeball to a blind person?
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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 ...
2
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0answers
40 views

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 ...
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 ...
19
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3answers
28k views

Why do mammalian red blood cells lack a nucleus?

How did the red blood cell in humans get to lose its nucleus (and other organelles)? Does the bone marrow just not put the nucleus in, or is it stripped out at some stage in the construction of the ...
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0answers
62 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 ...
9
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2answers
772 views

Which sex has higher variance of reproductive rate in modern societies - male or females?

Who has a more varied reproduction rate in modern western societies - men or women? The average rate is the same of course, but I wonder which sex have higher variance - higher variance means that ...
2
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2answers
191 views

Can human survive falling from 30,000 ft without a chute?

If someone falls 30,000 feet without a parachute; what are the chances of survival if they landed in the water?
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2answers
7k views

Does sour food cause sweating?

While eating sour food or candy, I start to sweat if it's sour enough. My body feels much hotter although my actual temperature is the same, my forehead starts sweating a lot and I feel like it just ...
3
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1answer
41 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 ...
2
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2answers
369 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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0answers
31 views
0
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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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3answers
297 views

How does a person get AIDS?

I am inquisitive to know about how a person contracts AIDS. Among the common masses it's still the belief that having sex with multiple partners causes the disease but that is not the case when read ...
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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
50 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 ...
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3answers
2k views

Is there any use of CO₂ in human body?

We all know CO₂ as a waste product of metabolism . Does CO₂ have any helpful role , apart from having a role in pH of blood ?
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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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1answer
2k views

What are differences between formation of embryonic disc in chick and mammal embryo?

Exam question which got lowest average points in my university: 1/5 average. No markscheme available so my attempt below. I assume that embryonic disk prefers to germ disk such that Formation prefers ...
4
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1answer
118 views

Do the eyes play any role in producing the visual experiences you have during dreaming?

Sometimes, you remember a vivid picture of a dream that you saw. What is the role of your eye in this experience? Please provide me with the answer that is as simple as possible since I am in Class ...
4
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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 ...
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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 ...
6
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1answer
753 views

Are there any effects of elevated Cysteine levels on cognitive function?

I'm looking at this diagram of homocysteine metabolism and see two distinct pathways that the amino acid may get metabolized to: with vitamin B12 it gets converted back into methionine, while with B6 ...
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3answers
2k views

Where does the 'C' in exhaled CO₂ mostly come from?

When a human being exhales CO₂, what is, by the numbers, the main source of carbon atoms exiting the body in this way? I mean what class of cells, or which tissues are the biggest on a pie chart of ...
3
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2answers
960 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 ...
3
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0answers
48 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 ...
8
votes
1answer
171 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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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 ...
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3answers
865 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
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3answers
75 views

Is the quality of sleep dependent on sleep duration?

I've been facing this lately, where I will wake up in the middle of the night after sleeping for perhaps 2-3 hours and be wide awake, but when I go back to sleep, I wake up more tired than before. ...
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 ...
3
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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 ...
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 ...
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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?
3
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1answer
256 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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2answers
5k views

Why is cold water more refreshing than warm water?

Obviously, the temperature of water does not affect its chemical composition. At least not in the ranges we are likely to drink it in. Yet it is clearly far more pleasant and refreshing to drink cool ...
0
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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?
6
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2answers
13k 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 ...