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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12
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2answers
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 ?
2
votes
1answer
346 views

Human body power consumption in still state

I'd like to know what kind of power human body needs to maintain life, in still state (average daily power consumption of an average man is also of interest). In terms of watts. I've only managed to ...
8
votes
1answer
60 views

What does the evidence suggest about how Neanderthals became extinct?

According to "Neanderthals: Facts About Our Extinct Human Relatives" (Szalay, 2013), Neanderthals dominated Europe during the last Ice Age, but may have died out before the arrival of Homo Sapiens ...
1
vote
1answer
369 views

Can food swallowed when a person is upside down reach the stomach?

If a person positions himself upside down and swallows food, will it reach the stomach against gravity? If so how?
5
votes
3answers
2k views

Why does it hurt when you take sweets, if you have cavities in your teeth?

When you have cavities in your teeth taking any sweetend drinks or food causes sensitivity or pain. What could be the reason?
0
votes
1answer
56 views

Can someone provide resources on human electromagnetic frequencies?

Pardon all of my questions below. I'm basically looking to find online resources regarding my inquiry. If you can answer any of them off the bat, that would be awesome!! It seems that humans and ...
1
vote
1answer
135 views

Characteristics of life

If all of the characteristics of life are required for something to be defined as living, how can we account people or other life that can not reproduce?
-1
votes
3answers
621 views

How come that we “feel” it when someone's watching us [closed]

The question is relatively easy (the answer however..). We all know this feeling "being watched" and more often than not this is a real thing. If someone is staring at us from the side or from the ...
1
vote
1answer
927 views

Are there more/less favourable phases of menstrual cycle to donate blood?

I was wondering whether it makes a difference when during the menstrual cycle a female is donating blood in terms of: Blood quality (iron or hormones levels) Her health/safety I am aware that ...
2
votes
2answers
475 views

What is the best color for a PPG signal (photoplethysmography)?

What is the best color for a PPG signal? Red, green, blue or infra-red? I'm asking because commercial oximeter sensors usually use a pair of red and infra-red LEDs. But recently, I've seen a lot of ...
0
votes
1answer
329 views

Why does air from the nasal cavity not go into the oesophagus?

When we ingest food, the epiglottis covers the trachea and the uvula covers the nasal passage. But what happens when we breathe? Why does the air go into our trachea and not the oesophagus?
6
votes
3answers
150 views

Why are diabetic people often overweight?

I was looking at diabetes the other day, and I noticed something strange. Lower amounts of lipase are a symptom of diabetes, as is overweightness. However, since lipase is the enzyme that breaks down ...
3
votes
1answer
349 views

Do hormones make men think of sex?

I remember hearing a saying that goes like "men think of sex every 7 minutes (or seconds?)". I take this saying to mean that men have sex related thoughts more often than women. I'm interested if ...
3
votes
1answer
6k views

What is the standard deviation of adult human heights within sexes?

The wikipedia article on human height reports mean height for many different countries by sex but it does not report standard deviations. What is the standard deviation of adult human heights within ...
6
votes
1answer
300 views

Why do people sleep with their eyes open?

It's a fact that some people sleep with their eyes open, but why does that happen? Is it normal behavior, not a symptom of any sort of disorder? Are there any (dis)advantages to sleeping with eyes ...
6
votes
2answers
637 views

Do animals get sick from eating dirty food or eating off the floor?

Humans have very strict tradition of hygiene, such as washing hands before eating, using utensils, and in general keeping as much distance between food and dirt as possible. At the same time, most ...
3
votes
1answer
81 views

What causes sinus pain and congestion?

When the sinuses flare up, it can get very painful. Thus, my question - what biological mechanisms cause the congestion and especially the pain associated with sinusitis?
3
votes
1answer
274 views

Why does the stomach ache if you take a brisk walk after lunch or dinner

After eating your lunch or dinner, if you take a brisk walk, most of the time your stomach aches. Why does that happen? What happens with respect to the body metabolism?
2
votes
1answer
52 views

Use of pigs for obtaining transplant organs

It is being said that organs can be obtained for transplant from the pigs. What is special about pigs that we are using them? Why can't we use monkeys or chimpanzees with whom we share a more recent ...
7
votes
2answers
2k views

Can one die from pain?

Is it possible that a human or any other creature can die from pain? I googled and found different answers. Some articles say Yes while others say No.
6
votes
2answers
263 views

Is there a preferred sleeping position for humans?

I remember hearing various sleep related advice as a child, like "sleep on your right side", or " have your head pointed in X direction". Is there any biological reason why sleeping on one side ...
1
vote
1answer
2k views

Is Diabetes sex linked disease

There are two types of diabetes mellitus. a. Type 1 diabetes mellitus b. Type 2 diabetes melliuts Is either of them a sex linked disease? Can either one be inherited? My book says, "this disease is ...
3
votes
1answer
1k views

Why do you need you room dark for melatonin release?

There is a light pollution movement that says lighting at night obstructs melatonin production. They say: What makes you fall asleep are changes in the level of the hormone melatonin ...
3
votes
1answer
109 views

In theory, would it be possible to create an injection of Vitamins, Minerals, sugars etc so that eating was no longer necessary?

I am wondering, out of pure curiosity, whether with current medical & biological science, (or indeed with accepted probable future developments in those areas), in theory, would it be possible to ...
1
vote
2answers
149 views

Why are animal births not taken as seriously as human births?

When humans give birth, more than often medical assistance is needed. Others gather around and frantically look for any way to help. But when an animal gives birth, it is usually seen as a moment ...
4
votes
2answers
7k views

Why do toenails grow much slower than fingernails?

As the title suggests, I've noticed that my fingernail grow much faster than my toenails. For instance, I usually trim my fingernails every two week or so, but for toenails the number would be about 6 ...
0
votes
1answer
24 views

Stopping the effect of hormone

Many hormones released by endocrine organs travel down in the blood and bind to specific receptors on the target cells. What then breaks that binding of the molecule with the receptor ? ( thus ...
-2
votes
1answer
175 views

Why do life savers hurt?

Why does holding a life saver peppermint candy to my tongue hurt? Does it have something to do with the chemical makeup of the candy?
2
votes
3answers
108 views

Is it possible to make humans extinct artificially?

Verging on the realm of science fiction, my question is that is there any theoretically possible way, biologically/chemically, with which the entire human race can be killed without affecting the rest ...
5
votes
1answer
60 views

Diabetes-diabetes comorbidity

Is it possible to have both type-1 (insulin-dependent) and type-2 (non-insulin-dependent) diabetes mellitus? That is, to have both insulin resistance and zero (or negligible) insulin production? If ...
2
votes
1answer
94 views

How can we distinguish blended flavors?

As far as I know, humans can distinguish between 5 basic tastes based on various molecules in food and their interactions. There's a level to all 5 so there can be an endless variety of tastes, and we ...
0
votes
1answer
9k views

What is it called when one human eye is seeing brighter color than the other?

What is the name of a phenomenon where one of the human eyes is seeing brighter/more saturated color than the other? I can observe the same object from the same position while alternating which eye is ...
-1
votes
3answers
73 views

Are there “multi-frequency” signals within a human brain?

I know that neurons can exhibit tonic and phasic firing, and also that a neuron is sometimes called an integrator. This makes me interested to know if there are activities in the brain that depend on ...
4
votes
2answers
5k views

What happens to the holes in the skull where teeth were developing?

In Skeptics.SE, a question regarding the skulls of children arose. Depicting a scary skull where the permenent teeth are "hidden" inside the jaws and the milk teeth are in the their place. After all ...
13
votes
2answers
281 views

Can parts of a human brain be asleep independently of each other, or vary in the times required for them to fall asleep?

I know that some birds and marine animals can continue complicated activity (swimming, flying?) while one hemisphere of their brain is asleep. I'm interested if human brain has some parts of it that ...
2
votes
1answer
915 views

fibroblast cells and fibers

I am interested in fibroblast cells in human arteries. Here are the things that I am not clear at the moment and I could not find any answer from the literature: What are the dimensions of these ...
6
votes
1answer
2k views

What causes the colors we see in eyes?

Genetics aside, what are the biochemical reasons the different colours of human irises? Also, related, how does eye colour change, particularly in childhood? (example: my eyes used to be blue, ...
8
votes
1answer
421 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 ? ...
3
votes
0answers
146 views

Can someone explain the color-changing unit (CCU) to me?

I've been physically carrying out serial tenfold dilutions on samples of Ureaplasma to work out the color-changing units (CCU). As a definition, the CCU is the highest dilution at which there is a ...
1
vote
1answer
50 views

What are the biological and nutritional benefits of having numerous smaller meals a day?

I have heard here and there that instead of consuming 3 largish meals (the traditional 3 meals a day), that consuming several smaller meals throughout the day is beneficial for health (and weight ...
1
vote
0answers
142 views

What naturally produced drug causes 'a tingleing euphoric rush' [closed]

What naturally produced drug causes a 'tingleing euphoric rush' through your body, as well as a 'wave of goosebumps'? I've always been interested in this sensation, two of the last times i can ...
0
votes
1answer
34 views

Distribution of nutrients throuought a drink made of plants?

In an attempts to eat my veggies for the day in one shot, I blended together a bag of salad with some water. The mixture separated by density, a thick top layer containing the bits of leaves, and a ...
7
votes
2answers
321 views

Do teeth have the capacity to heal?

Could a cavity in a human tooth "heal over" or possibly fill back in?
3
votes
1answer
122 views

Differences between right and left handed people

Are there any articles reporting any significant differences in behavior, attitudes, intelligence, appearance, etc., between right and left handed people?
7
votes
1answer
847 views

How do people who have lost both of their legs produce red blood cells?

As far as I know, just leg bones produce red blood cells. So, how people who lost their both legs produce red blood cells?
2
votes
1answer
390 views

What do rs id, allele coded 0 and allele coded 1 mean?

So, for a project I've been working on (different story), I've been looking at the HapMap Project, and their free online files. In their README file, they talk about how for each legend file for each ...
2
votes
2answers
89 views

E. coli, risk of infection?

There has been a warning about E. coli contaminated water in South Florida. Now I'm wondering are there empirical data or historic cases which show a correlation between E.coli levels in tap water and ...
2
votes
2answers
5k views

Can the excessive consumption of mineral water lead to kidney stones or other health issues?

I heard that drinking too much mineral (bottled) water could lead to problems such as kidney stones because of the high amount of minerals in it. Is it true? If so, what is considered to be excessive? ...
0
votes
1answer
805 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
0answers
56 views

Movement of stem cells from mother to fetus

Recent results from J Lee Nelson and colleagues (Sci Am. 2008 Feb;298(2):64-71; available as full text through Google) show that cells from the mother were found in a person aged 46. Logically, these ...