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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6
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1answer
149 views

How is color information transmitted from the eye to the brain?

Is color information sent from the eye to the brain frequency-modulated, or are different colors transmitted by different axons? I know that each ganglion cell is connected to multiple ...
2
votes
1answer
83 views

How many different smells can a human recognize?

How many different smells can a human recognize? If the space of smells is not discrete, how many dimensions it has (for example, the space of colors is three-dimensional).
0
votes
1answer
89 views

Death because of no radio waves [closed]

I read somewhere that a man dies if he is isolated from natural electromagnetic fields and waves. (I imply fields of radio frequencies and below.) Is it true?
6
votes
1answer
956 views

Why don't we have hair on palms?

We have hair all over the body except palms. What is the biological reason behind this? Thanks
3
votes
3answers
120 views

Can humans be printed?

Is it possible to spray stem cells on fully grown skeleton to get fully grown humans? Currently, just read about recent advances, and wondered if something like this is possible.
0
votes
1answer
274 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
votes
1answer
206 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
votes
2answers
154 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 ...
2
votes
1answer
96 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
votes
1answer
113 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
votes
2answers
133 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
votes
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 ...
1
vote
1answer
122 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
votes
1answer
306 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
votes
1answer
61 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
votes
1answer
123 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
votes
2answers
87 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
votes
1answer
453 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
votes
2answers
3k 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
votes
1answer
1k 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
votes
1answer
111 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
votes
1answer
109 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
votes
1answer
1k 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
votes
1answer
4k 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
votes
1answer
168 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 ...
3
votes
1answer
1k 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
1answer
86 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
votes
2answers
3k 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
votes
1answer
71 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
votes
1answer
173 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
votes
1answer
905 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 ...
1
vote
1answer
524 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
votes
3answers
1k 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
votes
2answers
144 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
votes
2answers
209 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
votes
1answer
201 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?
2
votes
1answer
60 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
votes
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
votes
1answer
65 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
votes
0answers
95 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 ...
-6
votes
2answers
244 views

Is love biologically useful? [closed]

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 ...
22
votes
1answer
525 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
votes
1answer
127 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 ...
-2
votes
1answer
93 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? ...
2
votes
1answer
178 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
votes
1answer
628 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
vote
1answer
115 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 ...
1
vote
1answer
725 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
votes
2answers
5k 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
votes
1answer
506 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 ...