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
141 views

Static in limbs

I have noticed that while sitting in the Sukhasan posture(picture below) for a long time, my feet suddenly become all stiff and i am unable to move it. What I deduce from the experience is that it is ...
2
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0answers
47 views

How well do we notice asynchronicity?

I'm stopped at a stoplight and, with nothing to do, my thoughts wander to the timed don't-walk sign that governs any pedestrians who might wish to cross the street I'm driving along. I can see two ...
2
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1answer
152 views

Why don't we have more cone cells (bigger fovea)?

Background Apart from being able to sense color, cone cells are able to perceive finer detail and more rapid changes in images, because their response times to stimuli are faster than those of rods. ...
4
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2answers
134 views

Is solving cancer required in order to avoid aging?

When the telomerase enzyme is not active the telomere shortens every time the cell duplicates leading to a reproductive limit (Hayflicks limit). On one hand this is a believed reason for aging. On the ...
1
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1answer
90 views

How HIV Affects and Its Treatment using Combination Therapy

Can someone please help me with the following questions. I've written my specific questions right after the text question. Human immunodeficiency virus (HIV) is a retrovirus. Its genome is a single ...
2
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1answer
85 views

Sodium levels and blood pressure

Why does low Na+ levels cause hypotension (low blood pressure). Alternatively, why does excessive intake of Na+ cause hypertension or high blood pressure? From what I understand, there are ...
0
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2answers
122 views

Chills down the spine with certain music?

I am sure many of us know the feeling of that tingling chill down our spines when listening to certain music. I experienced this most when my younger brother played an emotional piano piece for a ...
12
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1answer
2k views

Do we actually get more sick (flu/cold) during winter?

The word flu derives from the Italian phrase "influenza de freddo" meaning "influence of the cold". Indeed it is that time of the year when my colleagues seem to have the flu/cold more often than ...
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1answer
110 views

How is deviated nasal septum related to cold

I have a deviated nasal septum and I always suffer from common cold I was just wondering how a deviated nasal septum can be the cause for chronic common cold
3
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1answer
216 views

Is there a maximum pain threshold?

Is there a maximum threshold of pain a Human can experience, beyond which point there is no noticeable difference? I ask this question in part to better understand the definition of pain and its ...
3
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1answer
57 views

Gradual slowing breath, its effect on health

I've written a computer program which beeps, then beeps after 10 sec, then beeps after 11 sec, then beeps after 12 sec, etc. I tried the following "experiment" on myself: do only one breath between ...
5
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1answer
93 views

By what mechanism can hypoglycemia induce fainting?

Hypoglycemia (Low blood sugar) is said to be among the potential causes of human-faintings. I was wondering by which mechanism this happens. Google search results are abundant; there are lists of ...
4
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2answers
81 views

Do all humans experience flatus regardless of their diet?

Flatus frequency is affected by diet, so I was wondering if flatus production solely depends on the food eaten, meaning that some people never ever release flatus because they don't eat any ...
5
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1answer
327 views

Could alcohol be used as an antibiotic?

I was thinking about how alcohol is used to sterilize, and I was wondering if it would be possible to use alcohol as an antibiotic? if it kills bacteria, couldn't (conceivably) alcohol in the ...
2
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2answers
2k views

Why aren't we allowed to refreeze previously thawed breastmilk in refrigerator?

https://www.breastfeeding.asn.au/bf-info/breastfeeding-and-work/expressing-and-storing-breastmilk Previously frozen— thawed in refrigerator but not warmed 4 hours or less (ie the next ...
0
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1answer
816 views

For the human head, which direction is anterior, and which direction is ventral?

I read the wikipedia entry and I am sort of confused. In dog, the nose is toward the front. That's anterior. So I conclude that human nose is anterior. In dog, the head is on the back. So that's ...
4
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1answer
90 views

Why do some women have menstruation-like spotting throughout their pregnancy?

An interesting question that was asked during a lecture about human reproduction: what is the biological mechanism behind some pregnant women getting monthly spotting that they mistake for a regular ...
3
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1answer
86 views

How common is complete heterochromia?

How common is complete heterochromia? (One iris is a different color from the other) Are there any statistics available for this? If no, why not?
4
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1answer
575 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 ...
7
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1answer
2k views

Why is fructose not glucose the main energy source of sperm?

The seminal fluid contains fructose as the main energy source for the sperm and not glucose. Why is fructose and not glucose the primary energy source for these sperm, since glucose is the ...
2
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1answer
110 views

Scrotal temperature and vascularization

The testes (at least in human males) are vascular organs, the vascularization extending even o the interstitial spaces of the seminiferous tubules. The function of the scrotal sac, is to isolate the ...
2
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1answer
765 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 ...
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1answer
77 views

Body's decomposition

Does a human body decompose in a completely sterile environment ? If yes, what decomposes it ? And how fast ? What happens in vacuum ? Can it remain exactly the same ? Thanks
3
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2answers
2k views

Does bright environment strain eyes more than dim?

I'm trying to figure out how to modify my working conditions so that I can program longer without harming my eyes. Because doing so experimentally hasn't given conclusive results so far, I decided to ...
0
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1answer
63 views

Does the eye image interval refresh? [closed]

It's known the human eye takes 24 images per second. But does this refresh? For example after sleeping. Or will it always be the same interval? I talk about when the eye takes the images. So it are ...
6
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1answer
166 views

Does knowing the sex of each of a couple’s first N children have any marginal value in predicting the sex of child N+1?

Does knowing the sex of each of a couple’s first N children have any marginal value in predicting the sex of child N+1? By “marginal” I mean predictive power beyond other known effects, e.g., the race ...
2
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1answer
616 views

Transfer of antibodies in breast milk of humans

Why isn't the IgA secreted in breast milk digested due to proteases of the digestive system in the baby? Wikipedia says: The secretory component of sIgA protects the immunoglobulin from being ...
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1answer
391 views

Transfer of antibodies from mother to fetus

My questions: When does fetus begins to acquire antibodies from mother? Does it continue throughout the pregnancy? From Wikipedia: http://en.wikipedia.org/wiki/Passive_immunity This occurs around ...
12
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3answers
779 views

In Japan, the official average body temperature is 36.0 °C. Why so different from that of Europe?

The Japanese Wikipedia states that the average human body temperature is 36.0 °C (here,"ヒト"). The statement references the data from the Japanese government. Actually all of my Japanese friends think ...
3
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2answers
127 views

How far into a pregnancy is it before visible signs of it is apparent and risk of physical trauma increases

I'm doing research for a series I'm writing. in it the main character is pregnant however goes off to fight a criminal organization who have been killing her friends and i want her appearance to show ...
3
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2answers
146 views

How does Humira work when injected into patients with rheumatoid arthritis?

OK, I have rheumatoid arthritis and I've been injecting Humira 2 times a month for the last 8 months. As far as I know rheumatoid arthritis is simply an immune system disorder which makes the immune ...
0
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1answer
168 views

What is meant by 73 hour birth [closed]

I was reading an article, when I read a sentence saying, His mother ... nearly died less than three years later during Mathers' 73-hour birth. What does mean by 73-hour birth?
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0answers
103 views

Why do we feel pain in knees when we are facing fear [closed]

Just for information: I was watching Resident Evil, and every time I saw a zombie, I shook and then after a few minutes or just a few moments, I felt my knees ache! It was like someone is squeezing ...
2
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1answer
55 views

Antibody production in secondary immune response

Can IgG antibodies be produced in the secondary immune response without the help of T cells? Is the affinity of antibody for antigens higher during secondary immune response?
3
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2answers
2k views

Presence of MHC on red blood cells

Do red blood cells have no MHC? (I have often heard that they do not.) If so why are they not destroyed by immune cells?
3
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1answer
60 views

Alternating Ovulation

I have often heard that right and left ovaries alternate in releasing ovum. Is it always true? What controls this rhythm? Is it simply because the other ovary is unresponsive to LH or FSH? If so, ...
2
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0answers
91 views

What to do with a DNA sequencer? [closed]

My school is very fortunate to have a DNA sequencer, and I want to find an opportunity to learn how to use it. I'm currently taking AP Biology this year, and I hope to do an independent study in ...
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2answers
205 views

Is love biologically useful?

I thought about this statement a while ago: Natural selection sucks, it says those who love too much (or too many) will die the easiest and fastest. Sad but true. Only family (biologically of ...
20
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1answer
390 views

Extremely rare occurence of Heart cancer?

The occurrence of Heart cancer (similar, but not the same as Rhabdomyosarcoma) is extremely rare, about 1 per year according to MayoClinic. The reason for this rarity is explained to be the ...
0
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1answer
110 views

The probability of indirect human fertilization (follow-up)

This question is a follow-up to this one. I've been wondering how small that probability is. As we all know, "safe" sex, that is (correctly) using a condom and all that, isn't perfectly safe. So, in ...
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1answer
82 views

Would I still exist if [closed]

I've been wondering for some time, but say that my mother's egg chose another sperm cell, and a baby was eventually produced. Would I still be born, but end up with different characteristics/features? ...
1
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1answer
120 views

Need of Creatinine Phosphate

In muscle cells most of the ATP's phosphate is with creatinine phosphate. So why is the displacement of the phosphate group done ? Is it because creatinine phosphate would give it's phosphate more ...
2
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1answer
425 views

Glycolysis and Non-Glucose Sugars

In my biology book's section on disaccharide metabolism and glycolysis, it states that sugars other than glucose must be acted upon to enter glycolysis. Let's take sucrose as an example. Sucrose is ...
1
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1answer
100 views

What are the effects of muscle and fat mass on survivability?

If we have humans A, B and C who are different: A is thin (skinny) without significant muscle or fat mass. B is muscular C is fat Which one of them has the best body for survival in accidents like ...
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0answers
69 views

Harmful effects of radiation from cell phone towers? [closed]

As per this article - http://www.thehindu.com/news/national/mumbai-citizens-link-cancer-to-cell-phone-towers/article5139166.ece , people living adjacent to cell phone towers claim to have developed ...
1
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1answer
572 views

Why does shaving dehydrate the skin? Is there an hormonal effect involved?

I want to understand why the face becomes dry after shaving and if shaving affects hormones? I've heard that after shaving, hair grows back faster, why? Shaving damages hair follicles and they become ...
5
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2answers
3k views

Which human cells have the longest and shortest lifespan?

Which cells in a human have the longest lifespan? Which cell has the shortest lifespan?
2
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1answer
404 views

How many consecutive cell divisions are required to form the adult human body from the single cell zygote?

The preferred question would have been what is the total number of cells in a full term human foetus and how many cell divisions are required to reach that number. However estimates of total cell ...
6
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2answers
1k views

What did we learn with Nazi human experimentation?

Was there actually any useful knowledge gained from the Nazi experiments on human test subjects? Wikipedia cites freezing and phosphine gas reactions, but I would like to know other potential results ...
0
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1answer
189 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 ...