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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17
votes
2answers
547 views

Can parts of a human brain be asleep independently of each other, or vary in the times required for them to fall asleep?

I know that some birds and marine animals can continue complicated activity (swimming, flying?) while one hemisphere of their brain is asleep. I'm interested if human brain has some parts of it that ...
17
votes
3answers
5k views

What causes a 'stuffy' or 'runny' nose when you have a cold?

When humans get the common cold, a common symptom is a stuffy or runny nose. Is that the body's immune response or is that the virus's doing?
0
votes
0answers
12 views

Are apples really better for the immune system than most fruit? [migrated]

"An apple a day keeps the doctor away", the saying goes, implying that apples are somehow especially good for the immune system. But does this idiom have any validity to it? Are apples high in ...
0
votes
1answer
43 views

Amino Acid requirement + intake in relation to diet + meat type [closed]

I was arguing with a friend: I said: The Yulin festivals cannot be condemned by western culture, as we also kill animals in equally cruel ways. She said: It isn't just that the killing is cruel, ...
0
votes
0answers
39 views

Stopping the Gag Reflex: How and why does it work?

I was talking to some friends over the weekend, and one of them made a comment about gagging. He said that he read or watched that clenching your thumb with your other fingers (making a tight fist ...
0
votes
0answers
32 views

Why people have less hair than other primates? [duplicate]

Well as you can figure out, most primates such as monkeys, gorillas and chimpanzees, have all their body covered with fur. As we know they are evolutional "relatives" to us humans, but we dont have ...
1
vote
0answers
47 views

Why is sex pleasure giving activity but not childbirth?

Asking from an evolutionary viewpoint. Sex is a pleasure giving activity so that it encourages reproduction and spreading of genes. But childbirth ,the most crucial part of the reproductive process, ...
7
votes
4answers
14k views

Why do men have a higher hematocrit (red blood cell count) than women?

The hematocrit, also known as packed cell volume (PCV) or erythrocyte volume fraction (EVF), is the volume percentage (%) of red blood cells in blood. It is normally 45% for men and 40% for women. so,...
0
votes
2answers
59 views

How is UV light damaging DNA as the chromosomes are deep in the cell?

When UV light is on your skin it has to go through the cell membrane and to the membrane of the core. So it looks like that the DNA is protected. But it probably isn't. But can't membranes not been ...
2
votes
0answers
77 views

Why does it take many sperm for one sperm to fertilize an egg?

Hundreds of acrosomes must undergo exocytosis to digest holes in the zona pellucida. This is one case that does not bear out the adage, “The early bird catches the worm.” A sperm that comes along ...
4
votes
2answers
10k views

Applying saliva to mosquito bites

Is it true that; when you apply your own saliva to a mosquito bite it would stop itching ?
7
votes
1answer
5k views

Why do people sleep with their eyes open?

It's a fact that some people sleep with their eyes open, but why does that happen? Is it normal behavior, not a symptom of any sort of disorder? Are there any (dis)advantages to sleeping with eyes ...
1
vote
1answer
12 views

How do molecules signal pre synaptic neurons to activate? [closed]

How do molecules signal pre synaptic neurons to activate? and also is it more the structure or the elements in the molecule that allows it to activate the neuron also how do molecules bind to ...
4
votes
0answers
82 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, olives, milk, fish and cabbage. Are there examples ...
9
votes
1answer
15k views

What is the standard deviation of adult human heights for males and females?

The wikipedia article on human height reports mean height for many different countries by sex but it does not report standard deviations. What is the standard deviation of adult human heights within ...
1
vote
2answers
146 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. ...
3
votes
0answers
34 views

Why does crippling pain exist? [closed]

Some kinds of trauma can cause pain so severe that it makes you unable to move or do anything at all. It may put you out of action and unable to help yourself because of how excruciating it is. ...
0
votes
0answers
43 views

Is there an evolutionary advantage associated with migraine? [duplicate]

I have read Wikipedia article on Genetics of migraine headaches and I don't buy it Because genetics influence susceptibility to migraine, it can be shaped by evolution. Fitness-impairing ...
1
vote
2answers
71 views

Difference between water and tea [duplicate]

My friend heard that tea is worse for drinking than water because "cells have a special membrane and tea has special supplements and membrane doesn't let tea pass and this is why skin is dry even when ...
3
votes
2answers
74 views

What neurons make up the CNS?

I generally see it written that there are three types of neurons, classified by projection: (1) sensory neurons, (2) interneurons, and (3) motor neurons. Now, in the CNS, I don’t think there would be ...
2
votes
1answer
319 views

Is reproduction intrinsically part of life? [closed]

If all of the characteristics of life are required for something to be defined as living, how can we account people or other life that can not reproduce?
2
votes
2answers
50 views

Why is oxygen and CO2 measured in pressure instead of mmoles/L like other ions?

Na, K, Cl...All measured in mmol/L in plasma. Why is oxygen and CO2 measured in pressure (mmHg)? (I guess it has something to do with them being bound to RBC but I don't know why the difference).
0
votes
1answer
116 views

Why does the Vas Deferens detour over the pubic bone?

I was surprised to learn that the vas deferens detours over the pubic bone instead of taking the obviously more direct path. https://human.biodigital.com/widget?be=u1P&uaid=1ly5V Because I would ...
3
votes
2answers
66 views

Is saturation of olfactory cells able to create a feeling of another odour when it stops?

I'm looking for 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 example, with ...
1
vote
0answers
67 views

Why does sex give people pleasure [closed]

My question is Why does sex give people pleasure? I know that the pituitary gland secretes sex hormones and the sex organs receives the signal. How is it related to dopamine at last? Through ...
0
votes
1answer
84 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 ...
13
votes
1answer
8k 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 ...
-3
votes
1answer
66 views

Is it necessary to remove a bullet from the body? [closed]

So here is the proof: William Lawis Pace lived with bullet in his head for many years & even hit 100. However, both in real life and movies, we often see doctors struggling to remove bullets ...
3
votes
1answer
79 views

Living on pure glycogen?

I was recently fascinated when I learned about polysaccharides (I am a biology newbie) and was wondering about some of their properties. After doing some googling I was unable to find any information ...
3
votes
1answer
59 views

How do cancers eventually lead to death / other debilitating symptoms? [closed]

With regards to people I know or have read about who live with cancer, most of their symptoms are results of chemotherapy, surgical interventions, etc., which have the goal of eradicating the cancer. ...
1
vote
1answer
32 views

Resting stage of primary oocytes

In my biology textbook, I read that the primary oocyte gets arrested in the early stages of meiosis in prophase I (diplotene stage). I wanted to know why this is so. I searched google, and this ...
2
votes
3answers
7k views

What organs are absolutely needed by the human body?

The title is my question: what organs are absolutely needed (fatal if injured/removed) by the human body and perhaps animals in general? I'm not asking which organs are mechanically replaceable, but ...
0
votes
0answers
23 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 ...
17
votes
1answer
651 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 ...
1
vote
1answer
127 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" ...
13
votes
3answers
5k 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 ...
3
votes
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 ...
4
votes
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 ...
0
votes
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 ...
1
vote
2answers
102 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, ...
10
votes
2answers
2k 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 ...
4
votes
1answer
85 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?
5
votes
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 ...
4
votes
3answers
10k 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 ...
5
votes
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 ...
7
votes
1answer
89 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 ...
14
votes
1answer
15k 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 ...
11
votes
1answer
271 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 ...
4
votes
1answer
129 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 ...
0
votes
0answers
13 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 ...