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
votes
1answer
212 views

Are bacteria necessary for an individual's life, or, how long could a person live without bacteria? [on hold]

Bacteria are essential to life in that they are responsible for breakdown of organic substances, etc. but are bacteria necessary for an individual's life? In other words, how long would a human ...
1
vote
0answers
22 views

how food moves in horizontal coils of small intestines

This is a very very basic question, and I am looking at it more from point of view of physics. The small intestine is a highly coiled structure, which means it has horizontal coils as well. I can ...
9
votes
2answers
116 views
+50

Why do we urinate more when we are nervous?

This question is a result of my personal experience... But I guess that is common for many of us. My school timing is 8:00 am to 1:30 pm (usually). During normal school days I typically urinate one ...
2
votes
1answer
40 views

The human organism knows what we have to eat? [on hold]

My mother has told that if your organism needs a vitamin, you want fruits include that vitamin. For example you have lack of C-vitamin you would like to eat lemon. Is there any explanation for it, or ...
-1
votes
0answers
16 views

Case study about diabetic woman with comminuted fracture [on hold]

A middle aged diabetic woman is taken to ED after a MVA (motor vehicle accident). She has a compound fracture of her tibia. Imaging shows a comminuted fracture. In respect to this patient describe the ...
1
vote
1answer
30 views

How does ANF increase GFR?

ANF as we know reduce the Na+ uptake and K+ removal in the distal tubules and it also functions as a Vasodialator (?) But again it says that ANF increases the Glomerular filtrate ? But if it is acting ...
1
vote
4answers
73 views

Does the necessary Carbon Dioxide need to be in the atmosphere for mammals?

In the answers to this question, we've learnt that carbon dioxide is necessary for mammalian life. But, is it necessary in the atmosphere/to breathe it in? Or does the act of respiration give a ...
-2
votes
0answers
36 views

Is it possible to cause cancer in another person? [on hold]

Is it possible to poison someone's food on a daily basis in order to give them cancer? The thing here is that i'm worried someone at my workplace might be poisoning other people's water (each ...
0
votes
0answers
29 views

With humans, is being transgender innate, or caused by social factors?

In humans, is being transgender something that is innate, or is it caused (or made more likely) by social factors such as their political beliefs, their religious views or their social environment?
0
votes
0answers
30 views

What is the “seal”? [on hold]

There's a common phrase in English: break the seal The point at which you first piss after you have been drinking your favorite alcoholic beverage and at this point you will be pissing every ...
5
votes
3answers
168 views

Why do human ears have a lower boundary for the lowest energy perceivable signal than eyes?

I am currently hearing a lecture about human machine interaction. The lecturer is not a biologist (neither am I, we are both computer scientists), but he makes some statements about biology which I ...
1
vote
1answer
53 views

Role of Calcium and Magnesium in capacitation/acrosome reaction

During the acrosome reaction, the activation enzyme present in the sperm dissolves the corona radiata and zona pellucida enabling the sperm to reach the plasma membrane of the egg. Also calcium and ...
0
votes
0answers
12 views

Does the use of a Thiazide diuretic affect the ability of a hair follicle to absorb substances?

Thiazide diuretics are on the World Anti Doping Agency's, as well as the International Olympic Committee, list of banned substances due to it ability to mask illegal substances in urine. The rapid ...
0
votes
2answers
37 views

What percentage of human body's cells are contained in blood?

What percentage of human body's cells are contained in blood vs. the rest of the body?
1
vote
2answers
28 views

Can ingesting substances that are produced by the body cause a permanent withering of the organs that produce the substance?

This question is about substances such as insulin and some vitamins that the human body is able to produce on its own. Some substances that are produced by the body are also present in various body ...
0
votes
0answers
18 views

Insomnia & Bowel Movements [closed]

Serious question, first of all. I've had sleeping issues most of my life so I pay pretty close attention to my sleep/daily living patterns to see where I can improve my sleep. I've noticed that on ...
0
votes
1answer
19 views

How does the Pectoralis Major work when doing a bench press?

Disclaimer, I'm not a biology undergrad and I only know the basics about muscle movement. I know that doing a bench press works the chest, and specifically the Pectoralis Major because, well, I feel ...
3
votes
2answers
62 views

What does it mean to have different “metabolism”?

We hear talk of different body types, and that it is more difficult for certain people to lose weight than others. On the other hand, when my physician recommends that I lose weight, they say that it ...
11
votes
3answers
3k views

Superhuman eyesight

My ten year old son was reading car number plates that were too fast, too far away and at the wrong angle for any of us to read or even believe that it was possible for him to read. We thought he was ...
2
votes
1answer
40 views

Genetic abscence of backpain among teen girls? [closed]

I heard a study somewhere (I can't remember where) that claimed that teenage girls are genetically absent to experience high degrees of backpain, specifically from rigorous exercise. Strangely, of ...
3
votes
1answer
179 views

Perception of distant lights without glasses

I am fairly short-sighted and wear glasses pretty much all the time. Naively, I would expect that when I take my glasses off, the image I see should look very much the same as as a photograph that's ...
3
votes
2answers
340 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 ...
0
votes
0answers
32 views

Does addiction influence level of IQ?

Does addiction influence level of IQ ? And what is metabolic underling this change (dopamine receptors upregulation or something else) ?
4
votes
1answer
109 views

How can we measure cardiac output?

I could find a way which could find it by body oxygen consumption and there is another way to measure it by injecting drugs — measuring cardiac output by the so-called “indicator dilution method,” a ...
3
votes
1answer
75 views

What’s the reason for isovolumic contraction and isovolumic relaxation?

During cardiac cycle, there are two periods in which the heart volume doesn’t change, but there is a change in tension/pressure. It takes about 0.25-0.35 second to achieve this change. I searched in ...
1
vote
0answers
25 views

Is it possible that weak memory is due to interference between signals in the brain?

"Weak memory", as used in this question, refers to the inability to retrieve a memory that a person otherwise knows he has memorized earlier. An example of this is some fact snippet that the ...
2
votes
1answer
49 views

Biphasic T wave caused by digitalis toxicity

Digitalis is a drug that can be used during coronary insufficiency to increase the strength of cardiac muscle contraction. But when overdosages of digitalis are given, depolarization duration ...
4
votes
1answer
81 views

What actually are thoughts? [closed]

The human brain consists of neurons that transmit impulses like wires that conduct electricity.I am confused about where are our thoughts stored and what really are thoughts? For example if I think ...
3
votes
0answers
193 views

Why are fingerprints different even in identical twins? [duplicate]

Why are fingerprints different from person to person? It can't be genetics. Even identical twins has different sets of fingerprints. What is the deciding factor that form and shape our fingerprints?
2
votes
0answers
25 views

Neural correlates of the function of the cardiovascular system?

Are there any known neural correlates of the function of the cardiovascular system? I'm looking for research results that use standard brain imaging techniques (e.g. electroencephalography, ...
15
votes
6answers
1k views

Human evolution: Where *exactly* did the first human come from, whose parents were not?

Layman here. So I have never really quite understood this facet of human evolution, (or any other for that matter), in that, I understand the evolutionary process, but I get lost on the 'border' ...
13
votes
0answers
2k views

Why do we experience temperatures below 37 degrees Celsius as 'hot'? [duplicate]

We always prefer to be in 20-25° C, although our core temperature is about 37°? Why is our skin temperature lower than our core temperature?
8
votes
1answer
110 views

Why aren't green eyes more prevalent?

Why aren't green eyes more prevalent, given that the green allele is dominant over the blue one? My understanding is that human eye colour is determined by two genes: 1) HERC2, with alleles Bx, BB ...
3
votes
0answers
30 views

Can we artificially increase human growth using HGH?

Robert Pershing Wadlow was a man who lived in the early-mid 1900s and had hyperplasia of his pituitary gland, which caused him over-produce human growth hormone (HGH) and grow to nearly 9 feet ...
9
votes
2answers
256 views

During famine, does the human body do anything to prioritize which organs receive nutrients?

When food is scarce, the body slows its metabolism. Are there any other systems or processes that encourage prioritization of organs?
1
vote
0answers
50 views

How does estrogen influence collagen synthesis?

Through what mechanisms does estrogen interact with collagen synthesis? Especially in the context of elevated estrogen levels and genesis of purpura simplex .
4
votes
2answers
63 views

What is overdiagnosis?

What is overdiagnosis ? I have searched this Wiki result but didn't understood at all. Can you please explain the first two line of Wikipedia : Overdiagnosis is the diagnosis of "disease" that ...
5
votes
1answer
114 views

Why do we get 'bags under our eyes'?

Why do these circles form around the eyes if somebody is tired? And why does fatigue express itself around the eyes this way? Can I get eye bags very quickly in another way? ...
2
votes
1answer
39 views

Why does uterus have to be prepared every month for fertilization?

I'm just curious why it has to happen every month when the uterus could have been prepared from the beginning and kept that way throughout life or till a certain point. But why make and break it every ...
3
votes
1answer
77 views

Name (and meaning of the absence) of the white semicircle at the base of the fingernail?

At the base of fingernail, there is a white semicircle (see on the first picture). But sometimes there isn't one. My questions are: what is this white semicircle on the fingernail, and what causes ...
35
votes
1answer
18k views

Why Does Salt Water Help Sore Throats?

I am having some trouble understanding how salt water, a simple solution, could so effectively remove the pains of a sore throat. I do believe that the answer is closely related to hypo/hyper-tonic ...
-4
votes
1answer
48 views

Human Species of Males/Females [closed]

Why is it that when there is discussion about Race/Subspecies it is never about the genetic/physical differences between males and females. So every argument has been about physical and geographic ...
29
votes
5answers
959 views

Why do we age? or Do we have a theory of senescence?

There seem to be a number of ideas about why we age. Hypotheses include the gradual accumulation of cell metabolic products affecting organism function and the reduction of telomere length during cell ...
6
votes
2answers
55 views

SNPs and locations

I am new to reading raw DNA. When comparing two people's raw data, why does one person have a different SNP than the other, at the same location, on specific chromosome? But on a different chromosome ...
13
votes
2answers
2k views

Why I have to pee more often in low temperature? [closed]

I realised that I have to pee more often in winter or simply the temperature is low. Is there any scientific explanation, or just simply psychology?
5
votes
3answers
145 views

How does menstruation proceed during one period?

I'm simplifying things here: A. Does a woman bleed constantly, like a drop every 10 minutes? Two hours without pad or tampon and your underwear is dirty? or B. Does a woman bleed suddenly a ...
8
votes
1answer
58 views

What senses are active while sleeping?

During sleep, our body activity decreases. I am wondering on the extent of the lowering of this activity regarding our five senses. Clearly, the sense of touch is still very efficient since shaking a ...
8
votes
3answers
184 views

Why did humans become bipedal?

Somewhere in evolutionary history homo started walking upright and became bipedal. You hear these hypotheses that, by walking upright, they could see better across the grassy savannas to escape ...
2
votes
2answers
138 views

Agony, Hydrophobia and viruses in the light of evolutionary principles

I'm undergraduate physics student, but I've always been interested in biology. So I have a couple of questions about an application of the evolutionary principles to practice. Agony as the last ...
2
votes
1answer
39 views

Why are sperm cells not attacked by the female immune system? [duplicate]

Whenever a foreign particle enters into someone's body, it is attacked by the white blood cells. I just want how it is that, when sperms enter the female body, they are not attacked by the the woman's ...