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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Beta oxidation of saturated fats

In my text book there is an example of a 18 carbon long fat and it says that it can run 8 laps of oxidation. I don't understand why it doesn't run 9? 2 are removed each cycle? Thanks.
3
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1answer
93 views

Do humans have skin cells that trigger oxytocin release in the brain?

I was reading an article by Montgomery on the therapeutic effect of pets (Boston Globe, January 12, 2015), and I found this quote: All animals appear to have cells directly under the skin that ...
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2answers
5k views

What do ants do with our finger nails?

There is place in my house where I cut my nails. Here, there is an ant hole where an ant colony is seen. Whenever I cut my nails from here, they take my nails inside their hole. I was wondering what ...
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3answers
226 views

Is homosexuality an adaptation in humans?

Homo sapiens have menopause - as some other mammals (e.g. some Cetacea) - a phenomenon where older females live for decades after the end of their own reproduction. Perhaps homosexuality, that looks ...
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1answer
329 views

Calcium for Humans: Supplements vs Fortified Sources

I am intolerant to meat and milk products, but purely natural foods don't contain enough calcium for the Recommended Daily Intake. Links 2 to 4 (but NOT 1) avouch a correlation between calcium ...
3
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2answers
76 views

Myopia as a microscopic superpower?

A few years back my Physics professor made a joke that his myopia (i.e., nearsightedness) gave him a "superpower" that allowed him to see close objects much more clearly than someone with typical ...
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0answers
43 views

How pronounced is the difference if we would change the running direction for runners?

I was jogging when I asked myself this question: In running contests the standard running direction is counterclockwise; I also believe to remember that the regulation is very old (right back to the ...
5
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1answer
93 views

Why do we get tired [closed]

At the end of a day full of work, it is general for people that their eyelids start to feel heavy. Laziness takes over and we begin to yawn. We all know that we're tired at that time, but why people ...
5
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1answer
53 views

How do I know which alleles the parents have?

I have the following assignment where I am to look at the "tree" (not sure the english word) and assign whether or not they can be autosomal dominant or recessive as well whether they can be X-linked ...
6
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1answer
420 views

Evolution of umbilical cord and reason of its elongation

To answer a question myself, recently I've read that Years and years ago, a long umbilical cord enabled a woman to grasp her baby after birth and run away from predators" Update: $Question:$ ...
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1answer
112 views

How does visual sexual arousal work between the eyes, brain, and genitals/gonads? [closed]

When many people look at sexual images, they often can become sexually aroused, including full genital arousal, and feel urges, known more often used as "horny" as slang/urban usage. How does this ...
1
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1answer
78 views

Does homeopathic or herbal treatment of cancer have any scientific recognition?

Even though we have a very high tech society, cancer is still a serious issue. We humans still are not entirely capable of fighting cancer. Radiation and chemotherapy are still considered the best ...
9
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1answer
133 views

Can people with paralyzed eye muscles see?

As far as I am aware, the saccades of the eye are central to visual perception. If the eye is held still, the human stops seeing, even if light is reaching the retina and the visual pathway is intact. ...
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0answers
57 views

Why my right eye see warmer colors? [closed]

As the title says, my right eye see warmer color than the left one. I've seen a few people talking about that thanks to google, but I was unable to find a proper answer. So, what cause this strange ...
4
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0answers
32 views

Is it possible that the vapour form of propylene glycol could lower a humans blood oxygen saturation by the manner in which N2O does?

My understanding is that by inhaling nitrous oxide leads to the body not being able to take in as much oxygen as it usually would. Is it possible that a heavier soluble gas such as the vapour form of ...
6
votes
1answer
80 views

How can one accurately diagnose the cause of human hearing loss without surgery?

In a human, if you were to avoid a tympanotomy (surgical examination of the middle ear), how could you distinguish between a blocked Eustachian tube, a ruptured eardrum, or a perilymph fistula? For ...
9
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2answers
5k 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?
2
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1answer
44 views

Help reading gene markers

I'm sorry if "gene markers" is not the correct word. An edit could be appreciated but I don't study in an English speaking country unfortunately. Question overview: In a family, there is a genetic, ...
8
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1answer
74 views

What processes are responsible for focusing on an image only seen by one of the eyes?

When a person is spying from around a corner with only one eye, it's rather easy to ignore the other eye's image, since it's probably much darker, because one usually spies around a corner standing ...
5
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1answer
90 views

Effect of closed eyes on balance?

Suppose you want to stand on one leg. Doing it eyes open is not that difficult, but doing it eyes closed seems to be difficult. Why?
3
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1answer
74 views

What is the impact of stress on the human body?

Can stress trigger any changes in the human body? I'd like to know more about things less commonly known than, for example: sweating and tiredness. What are the long term risks of chronic stress? Do ...
4
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0answers
41 views

Does anxiety about weight or eating cause people to become overweight?

A while ago I saw this TED talk about the futility of dieting. The speaker suggests that a body maintains a homeostatic weight point and returns to that weight after dieting has stopped: Turns out ...
2
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0answers
65 views

Can DNA test of my grandparent's brother reveal my heritage from that branch of the family?

I'm thinking about doing that DNA test on all my grandparents to know where their genes come from. They are getting very old and I don't want to let the opportunity pass to gather more knowledge about ...
14
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2answers
6k 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.
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2answers
3k views

Will humans and animals be harmed by frequencies outside their hearing range?

The human ear (for example) is sensitive to frequencies from 20Hz to 20kHz. Any sound beyond that limit would not be heard by us naturally. Will it harm us (effect our ability to hear) when we hear ...
7
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1answer
134 views

Counterintuitive action of Vitamin D?

Vitamin D acts in a way which to me is counterintuitive. It functionally supplemets Parathormone. It in the intestinal tract steps up calcium absorption by altering nuclear gene expression and also ...
0
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1answer
33 views

How is cancer associated with host pathogen interaction?

Does cancer by any chance fall under host pathogen interaction domain? What I mean to ask is that, is there pathogen interaction involved in cancer? I went through this article: ...
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1answer
30 views

What is meant by clonal isolates?

With respect to this website: http://horfdb.dfci.harvard.edu/ what does the term clonal isolates mean?
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2answers
143 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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1answer
62 views
22
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4answers
10k views

Can humans eat grass?

Can a human eat grass and digest it? Could it be possible to use it as food just like other plants such as wheat or beans?
6
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1answer
122 views

Why is the brain dependent on glucose?

The strict dependence of the (human) brain on glucose has always been puzzling to me. While ketones can substitute for a portion of the brain's energy needs, it cannot substitute completely: blood ...
31
votes
1answer
4k views

What causes morning wood?

Sometimes men wake up with an erection in the morning. Why does this happen?
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1answer
44 views

Why do teeth decay of sugar?

Sugars is a common component in diet of mammals. Why then their teeth did not develop resistence to sugar decay?
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1answer
134 views

Interlocus Contest Evolution means suicide?

I was reading Matt Ridley's "Genome" book. I am trying to understand the Interlocus Contest Evolution in his X-Y chapter. I do not understand why the X and Y chromosome would want to kill each other. ...
0
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3answers
119 views

How does frame-shift mutation not absolutely ruin the organism?

I'm a bit curious as to how frame-shift mutation works. If you shift one amino acid towards another. How does this not affect the entire chromosome? Wouldn't this mean that the organism would be ...
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0answers
23 views

Over what range do Thyroid Stimulating Hormone (TSH) levels tend to fluctuate over the course of a day?

I understand that the majority of doctors consider the TSH test "the gold standard" for measuring thyroid function (examples stating that literally are here and here). The reference range for what is ...
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4answers
6k views

How does sodium in one's diet affect blood pressure?

Due to high blood pressure, my doctor has recommended I go on a low-sodium diet. So, that got me wondering what it is about sodium that drives this recommendation? What does sodium do to a body ...
15
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1answer
123 views

Why does mint oil feel cold on the skin?

When putting (japanese) mintoil on the skin it produces a cool feeling. You can experience this, when adding it to your bath or using a spray with mint oil on your skin. The cool feeling occures ...
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0answers
27 views

Regarding benzoic acid and its effects

One of the users on the chemistry s.e. mentioned that when benzoic acid forms in the body in response to other chemicals it might have a mutating effect on one's DNA. Is this true?
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1answer
22 views

Human population growth - where can I find the data?

Out of curiosity, I'd like play around with data of human global demography. Where can I find data that describe the "per region (per continent for example) population size" versus time since the ...
1
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1answer
33 views

What causes muscle spasms?

What causes muscle spasms with muscles that are not in the heart ? Could it be some sort of stimulus overload that causes a massive contraction?
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1answer
34 views

How does cancer of the larynx (laryngeal cancer) affect the respiratory system?

The larynx is part of the respiratory system and is responsible for producing sound (our voices). My question is how cancer in the larynx (voice box) affect the respiratory system overall? I ...
4
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1answer
5k views

Applying saliva to mosquito bites

Is it true that; when you apply your own saliva to a mosquito bite it would stop itching ?
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1answer
94 views

What happens when we stretch?

From the wikipedia page on stretching: Stretching is a form of physical exercise in which a specific muscle or tendon (or muscle group) is deliberately flexed or stretched in order to improve the ...
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2answers
3k views

Do biological facts determine when a human fetus is considered alive and human?

I often hear or read this statement: "It's not a human, it's a fetus." In other words, some think a fetus is non-human until a certain point. And another similar statement: "The fetus isn't ...
4
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1answer
53 views

How can a heart of human work if one of its valve is not working?

Yesterday I went to a hospital and heard a doctor say that one of the heart valves of a patient is not working. However, the patient was still alive and was healthy; the patient could walk and talk ...
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1answer
92 views

Why do fingers swell during cold winters?

When exercising, tissue in the hands may swell. This may be caused by the muscles generating heat, which leads to blood being pushed to the vessels closest to the surface of your body to dissipate the ...
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2answers
111 views

Why is my peripheral vision better for seeing in the dark? [duplicate]

I often walk around my house at night with the lights turned off and one night I noticed that looking straight at an object with very little light available made the object disappear from sight but if ...
4
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1answer
93 views

Do human-ape hybrids exist?

Since humans and apes share up to 99% of their DNA, can they interbreed? For example, a horse and a donkey seem to be just as distantly related and produce offspring. Mules, however, are sterile. ...