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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3
votes
3answers
812 views

Is lemon water an alkalizing agent in the body?

I was recently having a discussion with someone about whether lemon water actually increases the pH of your body (by which I assume they mean the blood); their claim was that once Citric acid was ...
0
votes
0answers
36 views

How can an autopsy return an inconclusive result? [on hold]

This may be a rather foolish/naive question, but I am confused as to how an autopsy can ever return an inconclusive result as to the cause of somebody's death? It does not seem uncommon for the ...
8
votes
3answers
13k 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 ...
3
votes
1answer
73 views

Will a 0.2g/mL sugar concentration cause vomiting in humans?

This infographic claims that the sugar content in a can of Coca Cola would cause vomiting if not for the phosphoric acid. In The First 10 minutes: 10 teaspoons of sugar hit your system. ...
12
votes
1answer
6k views

Why does scar tissue change color?

I was wondering why, when you are cold, scar tissue turns bluish or purple while original skin stays the same color. The only thing I can think of, is that maybe scar tissue gets less circulation ...
1
vote
1answer
37 views

Can my eyes adjust instantly to my friend's glasses? [on hold]

My eyesight is pretty much perfect, but I noticed that whenever I try any of my friends glasses, from really thin to extremely thick, my eyes seem to adjust to them within seconds and let me see ...
3
votes
0answers
69 views

Why do people die? [duplicate]

what is the reason people die naturally even though they have no known disease? I see people become physically weak at times they get old and die eventually in case they are not attacked by any known ...
1
vote
0answers
13 views

Why does a limb sting when it “falls asleep”? [duplicate]

Closely related to this question, but unanswered other than @Matthew-piziak providing a description and link that says: What is Paresthesia? Paresthesia refers to a burning or prickling sensation ...
3
votes
1answer
67 views

Is there a schema for how human behavior is genetically determined?

It seem one can distinguish three different kinds of genetic determinism of common patterns of human behavior: behavior that is directly wired into our nervous system, e.g. face-related mirror ...
3
votes
2answers
39 views

Bernoulli’s Principle in the Cardiovascular System

Below are graphs which illustrate the cross-sectional area, velocity, and fluid pressure through each vascular segment of the cardiovascular system. It makes sense that velocity and cross-sectional ...
3
votes
1answer
67 views

Feeling of spicy

I have done a survey on my friend When everytime they eat something spicy, They will eat ice or drink icy water. First, Mostly they feel nothing but a cool sensation. However when they finished, they ...
1
vote
2answers
269 views

What percentage of human body's cells are contained in blood?

What percentage of human body's cells are contained in blood vs. the rest of the body?
2
votes
1answer
134 views

Is there a hormone combination that makes humans grumpy?

Imagine a typical situation that is likely to give rise to a bad temper within an individual: a person is awoken very early in the morning by a sound of a lawn being mowed next door. Unlike expected ...
-2
votes
0answers
18 views

Is it possible for me to grow another inch? [closed]

I'm 14 and a half, 5'6, and got my first period at 11 and a half. My mother is 5'5 and my dad's 5'10. Can I still grow another inch? If it helps I was 5'4.5 for 2 years but i grew the inch and a half ...
3
votes
3answers
19k 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
vote
2answers
45 views

What would happen if brain neurons did not reduce their sensitivity to neurotransmitters after prolonged exposure?

From my understanding, neurons decrease their sensitivity to neurotransmitters by reducing the amount of receptors on the cell membrane in response to sustained neurotransmitter activity. One ...
2
votes
1answer
20 views

Do the enzymes and compounds in saliva help with stain removal?

Does spitting on stains help with removal? Saliva is high in amylase that should help with the breakdown of protein rich stains like blood and semen. It also contains antimicrobial enzymes and ...
1
vote
0answers
107 views

Which of these methods is both effective and reliable in elongate muscle and tendon for use in humans: growth factors or stem cell technology

Which method is it the most effective, but also the most reliable for elongating muscle and tendons for clinical trial; using modern growth factor technology or using modern stem cell technology? ...
9
votes
1answer
72 views

What bacteria do unborn babies contain?

This Scientific American article states that "[human] infestation [by bacteria] begins at birth". This would suggest that unborn babies are free from any bacteria. However, if the mother catches a ...
12
votes
4answers
5k views

Why we have no enzyme to digest cellulose?

As we know, cellulose is the most abundant polysaccharide in nature. Why don't we have any enzyme to digest cellulose?
1
vote
0answers
16 views

Why we see a reddish vision in dark room after seeing a bright light?

When you enter a dark room after seeing sunlight or other bright light, you see a reddish speck of light hovering around your vision. This vision generally disappears after a few minutes. Why this ...
13
votes
1answer
15k views

At what age do babies begin to synthesize their own antibodies?

When babies are first born, they receive their antibodies from their mother (I assume because they do not yet have the capacity to synthesize their own). So my question is, at what age do babies ...
3
votes
0answers
42 views

How long does conception take?

I know that conception is a multi-step process. A sperm fuses with an egg. Its contents diffuse into the cytoplasm. Dad's DNA is transported to the nucleus. Proteins are gradually made from Dad's ...
-1
votes
0answers
36 views

Heart Rate while Eating?

I was wondering does heart rate increase during the consumption of food (chewing, starting the digestive system)?
0
votes
0answers
48 views

How to mimic / approach some animals/insects' anabolism?

This article states that some shelled animals - spiders, scorpions, crabs, worms and other creatures - have metal atoms in their claws, jaws and fangs. I believe through anabolism, since they eat ...
3
votes
1answer
72 views

Do our belly buttons consist of scar tissue?

I read an interesting post on Facebook the other day saying that we all have a visible scar since birth - our belly button. This got me thinking (and research for me only found results regarding belly ...
1
vote
1answer
64 views

Is each generation getting older? [duplicate]

So we know that our sperm and egg cells get set aside relatively early so that they aren't going through unnecessary cell divisions and causing DNA damage or telomere shortening, but since each new ...
3
votes
0answers
36 views

Is there a mechanism by which mammals lose interest in a partner after mating?

I'm reading the book called "Cupid's poison arrow", which revolves around a rather simple assumption: most mammals, including humans have a genetic program that is responsible for ever increasing ...
8
votes
1answer
542 views

Why do people feel pleasure when using roller coasters / centrifuges?

The feeling when using an amusement park unit is usually a pleasure. Why is it not a pain instead? Are there advantages, from an evolutionary point of view, in loving this potentially dangerous ...
3
votes
0answers
22 views

Why are humans mostly right-handed? [duplicate]

Most sources I've seen say that about 90% of humans are right handed, and 10% are left handed. Why is this? My only guess would be that it has something to do with different parts of the brain ...
7
votes
2answers
159 views

Are unilaterally deaf people able to determine where sound comes from?

My question is on people deafened in one ear, but normal hearing in the other. Time and level differences between the two ears are only part of how the human body can localize the source of the ...
4
votes
1answer
818 views

Is there a relationship between Melatonin, Norepinephrine and depression in humans?

I'm reading a booklet on melatonin published in 1996, titled "Melatonin and the Biological Clock". This particular paragraph caught my attention and I would like to better understand what it means: ...
5
votes
4answers
6k views

Can nosebleeds cause death?

Can epistaxis or nosebleeds be a of cause death?
14
votes
2answers
722 views

Why does mouldy food make you sick?

Bread gets mouldy pretty quickly, and my parents (both of whom are nurses) throw out a loaf of bread after a spot of mould is seen (because "if you can see one spot, it means the whole thing is ...
2
votes
3answers
105 views

Blood urea nitrogen and usage of proteins?

I have been reading some books and am getting slightly confused. Here is roughly what I have read. The greater the blood urea nitrogen the greater the usage of proteins (since blood urea nitrogen ...
8
votes
4answers
470 views

Why people like to see pornographic scenes, but do not feel the same about eating scenes? [closed]

This question may seem funny, but I think biology must have good answers. I think no more explanation is needed. I really thought about this and searched for an answer, but there is nothing yet. If ...
9
votes
1answer
345 views

How do female hormones cause blood to clot?

On most female-hormone supplements you get a warning that is something like this: The use of a combination hormonal contraceptives (CHC), like NuvaRing, is associated with increased risks of ...
6
votes
2answers
7k views

Does mixing alcoholic drinks really make you more drunk?

There is plenty of anecdotal evidence ("beer after wine and you'll feel fine, wine after beer will make you feel queer") that mixing alcoholic drink types leads to a stronger effect, but I can't find ...
10
votes
3answers
236 views

Why are the organs for reproduction and urinary excretion combined?

We eat food for getting energy to our body parts, and we excrete the wastes through urine, feces, and perspiration. Why has nature combined the urinary tract with the genital system (urogenital ...
2
votes
1answer
31 views

Why are our bodies created to itch when histamine is released by our immune systems?

Why do bug bites and cuts itch when scratching them clearly doesn't help us survive? Did our early ancestors need to rely on this itching sensation, or is it just that the receptors for itches just ...
2
votes
1answer
33 views

Why is there a compound highlighted in red in a KEGG Module search?

Considering the following module: http://www.kegg.jp/kegg-bin/show_module?M00115+C00003 why is the compound C00003 marked in red?
1
vote
1answer
13 views

What information does the KEGG Module statistics page show?

While browsing through the home page of KEGG Module, I clicked the button named Module statistics. Can someone tell me what does these numbers signify? What are they the statistics of?
14
votes
1answer
20k views

Can a person really die quickly from biting their tongue?

A common trope in certain circles (like Eastern martial fiction), is someone committing quick suicide by biting his or her tongue. But is this really possible? The internet turns up millions of ...
0
votes
1answer
37 views

Would a human survive eating only living ants?

After reading an admittedly foolish question about 1 googol ants vs. 1000 humans, I had a question. Could a human survive solely on eating ants (common ants, not the stinging kind, or leafcutters ...
0
votes
0answers
54 views

Phytoestrogens from hops in beer and estrogenic activity in humans

There is a saying that phytoestrogens from hops can cause breast growth (gynecomastia) in male beer drinkers. Are there any reliable studies linking beer consumption to increased estrogenic activity? ...
5
votes
1answer
2k views

Is the Michael Jackson skin pigmentation disease realistic?

Quoting wikipedia: Jackson's skin had been a medium-brown color for the entire duration of his youth, but starting in the mid-1980s, it gradually grew paler. The change gained widespread media ...
1
vote
0answers
20 views

An obscure reference to a “golden vein” [migrated]

In some Yiddish literature there is reference to a 'golden vein' which seems to refer to Hemorrhoids. Is there any reason that hemorrhoids would be described as golden? Edit: In response to the ...
3
votes
1answer
57 views

What are the most important factors influencing a person’s gut microbes?

You are your bacteria! The probiotics and the antibiotics... There has been on going discussions about how our gut bacteria is important for a healthy lifestyle. Figure 1: Schematic diagram ...
16
votes
4answers
2k views

Where’s the flaw in my proposed TB Treatment?

Ten years ago, I emailed a prominent lung specialist with my suggestion for a treatment for Tuberculosis. His lack of response led me to believe that the idea had no merit whatsoever – but I had no ...
19
votes
1answer
4k views

What do you see when your eyes are closed?

If you are in pitch black and you close your eyes, you sometimes can see strange shapes of various colors. A lot of the time these shapes and colors change as you observe them. This phenomenon still ...