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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What happens when mammalian ovum fails to get fertilized?

If mammalian ovum fails to get fertilized , which of the following is unlikely ? a) corpus leuteum will disintegrate b) estrogen secretion further decreases c) primary follicles starts developing d) ...
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11 views

Lyonization and Turner's syndrome

If lyonization is basically inactivation on X chromosome, and Turner's syndrome patients have only one existing X chromosome, what is the difference between healthy women with inactivated X chromosome ...
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1answer
565 views

How fast can a human run?

I'm a runner (cross country) and I'm always amazed at how fast Olympic sprinters are. There's a lot of hype about those in the 100-meter dash being the fastest in the world, and we're constantly ...
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1answer
87 views

How can alcohol cause blindness?

Strong alcoholic beverages (e.g. moonshine) are reported to have caused blindness amongst some people. How exactly can alcohol make someone go blind? Is that because different forms of "rubbing" ...
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3answers
4k views

What is the evolutionary reason behind the fragility of teeth?

Almost all organs in the human body have a rather large threshold within which the organ or tissue is capable of repairing itself using materials supplied by the body, whether it's made from organic ...
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1answer
2k views

Does a woman contain all the genes needed to make a man?

I know the answer of inverse is at here, but how about this question? I also read this question, can I imply to human that a woman can also contain all the genes needed to make a man? Edit: I ...
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1answer
8k views

Which blood vessel carries the most impure blood?

There is a question in my Biology textbook: "Which blood vessel in the human body carries most impure blood after few hours of meal." The answer is given as Renal artery. But I think the ...
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0answers
53 views

What approximate age does a human baby have to be to survive unassisted? [on hold]

I'm interested in determining the youngest age at which a human child could survive without external assistance. For this question, I want to exclude negative outside influence or threats. For ...
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2answers
2k views

What part of food gives the blood red color?

Roughly, what I know is, when we eat food it goes into our: Stomach > Small Intestine > Large Intestine > Rectum. So, it just moves through a digestive pipe. What I don't understand is, what part of ...
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2answers
91 views

How do T-cells determine which cells they've already inspected?

From what I understand, T-cells are constantly traveling in the body, inspecting cells by looking for antigens. If they're self antigens, then the T-cell doesn't attack, whereas if they're non-self, ...
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1answer
26 views

Does mechanotransduction of cells play a role in the biocompatibility of titanium?

What exactly is mechanotransduction as the information varies between sources. Some sources indicate that mechanotransduction is the underlying principle where cells pull on the surface they grow on ...
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1answer
61 views

Do animals have different taste preferences within the same species?

Humans (especially children...) seem to dislike certain foods or drinks, that other humans seem to like. Common examples are coffee, french cheeses, milk, fish and cabbage. Are there examples of ...
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20 views

Can i freeze in 40 degree warm water? [closed]

I remember someone telling me that you can freeze in water even if its above your body temperature? Not that I am scared but what if you're in a hot tube for 30 hours while eating and drinking ...
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1answer
52 views

Evolution to store limited Fat

Why are our bodies not evolved to store only limited amounts of fat, which won't kill us with all diseases associated with obesity? Wouldn't obese people die faster and clean the gene pool for people ...
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2answers
1k views

Why do Hot/Cold drinks taste sweeter once returning to room temperature?

Now, I know this is a very bizarre question, and I tried to find a correct exchange for this, but it might relate to biology/science as it being our taste buds and everything. I am so sorry if there ...
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0answers
35 views

How is DNA digested by the human body? [closed]

Suppose I (a human being) eat some food? How would my stomach break down and digest the DNA in the food? I believe ultimately it should break down into and be passed out as uric acid but I'm not sure ...
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0answers
11 views

Is there any study on odour remanence in human olfactory system?

does anyone here knows about at least one scientific study about how odours could impact human olfactory system and create some phenomenon that could be loosely compared to retina remanence? As an ...
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1answer
82 views

What causes anorexia nervorsa?

I've heard of anorexia nervosa being a severe loss of appetite. I'm wondering what causes such disease in humans?
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1answer
2k views

What's a mouth ulcer/canker sore “made of”, and why do they develop?

Mouth ulcers are red/white rings with a crater. They are sore and last for 7-10 days. What I want to know is what they are 'made of' - i.e., what is the ring filled with, and why is the centre crater ...
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3answers
8k views

Is the human body composition real?

In Fullmetal Alchemist when Ed goes to disprove to Rose the Sun God's "miracle" to bring humans back to life by proving that science (in the form of Alchemy) can create people by saying Water (35 ...
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4answers
3k 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 ...
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0answers
48 views

Does the Anthony Walsh book “Is Race a Socially Dangerous Idea” have biological merit?

Preface: I'm not a biologist asking this question, but I do find this curious. I was reading Science Wars by Anthony Walsh, and in a chapter titled "Is Race a Socially Dangerous Idea" he outlined the ...
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1answer
88 views

Can a Turner syndrome patient develop male characteristics artificially?

From an answer to the question Can stem cells from male convert to cells of female-only organs, and vice versa? Y chromosome is the sex determining chromosome with SRY gene that determines testes ...
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1answer
13k views

What is the female equivalent of the morning erection that some men experience?

There was question about what causes "morning wood." It was answered that the erection in the morning is caused by decline of norepinephrine during REM sleep. Which in part allows to prevent ...
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1answer
251 views

What biological functions does crying serve?

Tears suddenly start flowing out of our eyes when we find our long lost friend or when someone unexpectedly decides to break up with us. Do tears really save us from harm? Or are they just the reflex ...
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1answer
126 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 ...
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1answer
52 views

How do I tell if the mosquitos in my New York City apartment can carry Zika?

The species that carries Zika, A. aegypti, is unlikely to be found in New York. However, the related species A. albopictus is prevalent and quite concerning. So this question is focusing on A. ...
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1answer
79 views

Which part of the reflex arc takes the longest time?

If the reflex arc is composed of 4 parts: Activation of sensory receptors, Conduction to and from the CNS, Transmission across the neuromuscular junction & Activation of the muscular contractile ...
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0answers
12 views

Modeling a patient's parameters (SPO2, HR, BIS etc.) to their effect on the patient

I'm currently using code (C#) I wrote which creates a 3 compartment model to simulate the concentration $C_{p}$ of Propofol in blood plasma using the Schnider and Marsh pharmacokinetic models. I ...
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1answer
45 views

What actually happens to the human body during fasting/starvation? [closed]

I recently came across a UN study which advocated that controlled fasting can be beneficial for the the human body and I am fascinated by stories of wilderness survival against the odds. It piqued ...
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1answer
29 views

Why do people cut back on kilo-calories?

I am learning about specific heat in science and I learned about how the specific heat for water is called a calorie, but that is different to what is on the food label. On the food label, that ...
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3answers
278 views

At what temperature do human bones disintegrate?

I know, the human skin can get damaged as quickly as 2 seconds, when exposed to temperature above 80 Celsius. However, what about human bones, say the skull? For example, when you cook a meal, at ...
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1answer
32 views

Amino acids in human cancer cells expose dextrorotation?

I would like to know if the amino acids in the human cancer cells are dextrorotatory or levorotatory. I mean the majority of them. They expose levorotation just like the amino acids in the normal ...
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T cell sensitivity and persistence to specific bacterial proteins

Currently, the standard tests for Lyme Disease measure antibody production after exposure to a bacteria, Borrelia burgdorferi. Often, the tests are performed too soon after infection, before ...
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1answer
59 views

What is the difference between a Human Being, Homo Sapiens and a Neanderthal?

I know that the Neanderthal's are a branch of the Human Being but how do all three relate to each other or more specifically what is the difference?
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56 views

Why are sarcomas rare compared to carcinomas?

A sarcoma (from the Greek σάρξ sarx meaning "flesh") is a cancer that arises from transformed cells of mesenchymal origin. Thus, malignant tumors made of cancellous bone, cartilage, fat, ...
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1answer
8k views

How much gas is exchanged in one human breath?

When we breathe, our lungs absorb a portion of the oxygen in the air, and replace it with some amount of carbon dioxide and water vapor. Typically, how much $O_2$ (in grams, milliliters, or moles for ...
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2answers
46 views

Can all elements be found in our body? [closed]

There are many Natural occurring atomic elements. Can they all be found in the human body?
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2answers
824 views

What would happen if a person had the right side of their body totally removed (including the brain)? [closed]

What would happen (in reality or theoretically) if the entire right side of a human's body was removed? Could they live (aside from all the probable infections and such)? I would guess that humans ...
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0answers
43 views

Why do people tend to stand on one leg? [closed]

I know for a fact, by observing people and from own experience (you can try it yourself while standing, but not too consciously and in a loose way) that they (like birds), while standing, tend to do ...
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1answer
185 views
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2answers
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Do Class A biosolids count as organic fertiliser?

Does Human Waste, which has been treated at least twice to remove pathogens & remove stink, still count as organic despite it passing the EPA's class A standard? If so, does this mean that ...
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1answer
21 views

Cell division - meiosis

Really confused. How many chromosomes pairs do humans have in their sex cells? How many single chromosomes do humans have in their sex cells?
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0answers
12 views

Why human hair is losing its color over time? [duplicate]

Human hair is losing its color over time, that's a known fact. I would like to know why, meaning what biological processes are involved in this? Also, is it part of the DNA somehow, i.e. the exact ...
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0answers
12 views

Is salivation decrease during sleep beneficial?

Papers [1, 2, 3] tell that a salivation decrease is not only unpleasant, but harmful for dental health. What cause that decrease? What is the reason for it and do animals have it? I guess it's a ...
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2answers
13k 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
2k 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 ...
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1answer
24 views

Do we know a complete list of nutrients that humans must ingest to live?

When the people who are making "nutritionally complete" foods like Soylent are developing their product, how do they know that they've covered all their bases? You need to have protein, carbohydrates, ...
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3answers
111 views

How does the brain immediately know when one's thirst has been quenched?

The question struck me the other day when I drank a glass of water. I understand that there are at least two conditions under which the brain signals thirst: extracellular thirst, when there's not ...
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1answer
72 views

Acrosomal enzymes and the female reproductive tract

My textbook wrote that the reason why acrosomal enzymes are so securely contained within the sperm (thus needing capacitation to facilitate their release) is to prevent any premature release in the ...