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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0
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1answer
16 views

Human Blood vessels, [duplicate]

Why is blood drawn from veins? Is it because veins have a large lumen? Or is it because the blood is flowing at a lower pressure and makes discharge easier? Is it safer to draw blood from veins?
-2
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1answer
41 views

Selectivity of anti-bacterial affect of oxygen

As far as I know, oxidizing agents (AKA reactive oxygen species or ROS) are potent antimicrobial agents that act on a broad range of bacteria and viruses, as well as inactivating certain toxins. Is ...
23
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2answers
2k views

Why is rabies incurable?

I'm still not sure about the mechanics that lead to rabies being incurable. I know that it can be treated before any symptoms show up, but why is it that once symptoms show the person is a dead man ...
15
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1answer
20k views

What is the composition of human feces?

Are there any studies or general information on the composition of human feces? I'd specifically like to know the percentage of carbohydrates and amino acids relative to the amount that was ingested ...
-1
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0answers
22 views

What are the differences between good (pathogens) and bad (beneficial) bacteria? [on hold]

What are the main differences between pathogens and beneficial bacteria? Is it the only difference that one create a poisonous waste material and other not, or there is something else?
3
votes
1answer
50 views

Why do people sing?

I was wondering the why people sing, but from a biological point of view. Is it necessary for our body? If it is so, then why can't everyone sing well? Is it in direct relation with neurotransmitter ...
3
votes
1answer
52 views

How are some people able to continue growing after reaching maturity?

This is technically a cross-post of a question posted last year concerning gigantism and how certain people are able to grow far past expectations after it's assumed they've reached maturity. How are ...
-2
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0answers
25 views

what are two materials that are reabsorbed during the reabsorption phase in the process of urine formation? [closed]

what two material are reabsorbed during the reabsorption phase in the process reabsorption phase? and are there more than two. If not the two main ones?
-5
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0answers
20 views

Is the human brain the muscle with the greatest leverage? Menu to brain [closed]

1) The brain being our best lever, muscularly, shouldn't we treat it better? 2) Diet being our best conduit to good health in general, don't we need more competition in the food market, relative to ...
5
votes
1answer
97 views

Is there a mechanism by which mammals lose interest in a partner after mating?

I'm reading the book called "Cupid's poison arrow", which revolves around a rather simple assumption: most mammals, including humans have a genetic program that is responsible for ever increasing ...
4
votes
1answer
55 views

why do overweight individuals sweat more than ordinary people?

A common phenomenon that I have noticed while traveling in buses is that overweight individuals seem to sweat a lot more than people with ordinary weight. Is this a coincidence or is there some ...
-5
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1answer
40 views

Contradiction to evolution [closed]

It is said that evolution occurs according to requirement ..if it is true then women who really needs safety should be strong and men who don't should not be strong...isn't it contradictory?
0
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1answer
35 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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2answers
536 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 ...
0
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0answers
24 views

What are the chances that a hemophiliac male and an unaffected, non-carrier female could have a baby that is a hemophiliac male? [closed]

The hemophilia gene is located in the X chromosome, which male babies get there X chromosome from their mothers. So the chances of this male baby being hemophiliac is zero. Correct?
-1
votes
2answers
51 views

Wouldn't it be more efficient to let the kidneys flow into the intestines?

So I was thinking about how much fluids we lose when we pee. Then I realised that it would be much more efficient to remove the bladder and let it flow into the intestines so that the fluids can be ...
0
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1answer
64 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 ...
1
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0answers
48 views

If the liver can regenerate why can alcohol abuse permanently damage it?

The liver is a fairly unique organ in that it has the ability to regenerate itself even if parts of it are removed/damaged. It is a well known fact that continual alcohol abuse damages the liver and ...
2
votes
1answer
120 views

Is there a genetic reason explaining the difference of the height of male and female?

The male and female height difference seems to be around 1.08 if all cultures are counted from these stats: https://en.wikipedia.org/wiki/Human_height Can this ratio, 27/25, be explained by genetics ...
-1
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0answers
44 views

Is there an evolutionary purpose for postpartum depression in human females? [closed]

Essentially what the title says...It seems odd that at the very stage in which new life is supposed to be protected, we see new mothers at a higher risk for particular kinds of mental illness (...
1
vote
0answers
17 views

Robertsonian translocation on the same chromosome

is there any big difference between Robert-son-i-an translocation between two 13 chromosomes comparing to a translocation between 13 and 14 chromosomes
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2answers
53 views
14
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4answers
4k views

Why does hair grow after trimming but remains at a constant length after a while?

Some hair especially body hair regrows after trimming but stops growing after a while. What is the mechanism behind control of hair growth and how is the length limit determined?
0
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0answers
22 views

How do implantable devices interact with the human body?

Are there some general methods to prevent biochips implants for unwilling recipients? If implantable devices are embedded in the human body, how does the human body detect and react to foreign ...
6
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3answers
81 views

Cancer biology: Can tumors form from cells that are genetically identical to non-cancerous cells?

Can a tumor begin to form without any genetic mutations? I'm specifically interested in a tumor which could later lead to cancer.
20
votes
1answer
286 views

What's the mechanism for being mentally tired?

I notice that after long tests, or long periods of critical thinking, my body and mind feel noticeably tired. Why does this happen? Are the neurons in my head not firing as quickly, or is there just a ...
3
votes
0answers
23 views

Does increased calorie intake cause increase in libido in humans?

I'm interested in the effect of increased calorie intake on sex hormones and chosen mating strategy in humans. I'm aware that humans have a dual mating strategy - somewhere between pair bond and ...
4
votes
0answers
43 views

Does variation in human gut length vary predictably with diet of ancestors?

Background: Numerous online searches, textbooks and other sources seem to pin the average length of the human gut from mouth to anus (oroanal) between about 5-10m in length. To pick a reputable ...
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0answers
9 views

How long can/will an infant hold his/her breath as part of the dive reflex?

Various other questions on the site have talked about the Diving Reflex, which is also known as the Mammalian Diving Reflex. This reflex is observed in mammals of various species, but also in human ...
2
votes
1answer
85 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 ...
4
votes
0answers
23 views

Reason for variation in the site of onset of edema

What is the reason for the observed clinical difference in the earliest site of onset of edema in cases of different etiologies? For example, in Congestive Heart Failure, it appears initially as ...
17
votes
3answers
16k views

Why do people have antibodies against other blood types?

The ABO blood type divides each blood type according to whether they have the "A" and "B" antigen(s) (AB has both, O has none). People also have antibodies against the antigens they don't have (AB has ...
2
votes
1answer
58 views

What does completing the course of antibiotics accomplish?

This article from the WHO states: If you stop treatment early, there is a risk the antibiotics won’t have killed all the bacteria that made you sick and that it will mutate and become resistant. ...
17
votes
4answers
5k views

What causes the development of antibiotic-resistant strains of bacteria?

I understand bacteria have become resistant to antibiotics due to selection pressures, but how do resistant bacteria process antibiotics when exposed to it, compared to non-resistant bacteria. Also, ...
7
votes
1answer
180 views

How do tea, coffee, and beer dehydrate you?

For the long time I am trying to find out if the following is truth: They say that some beverages dehydrates. I heard that about tea (sometimes green, sometimes black, sometimes both), coffee, beer ...
2
votes
1answer
73 views

Can drinking caffeine, alcohol and other diuretics be part of a good drinking regime?

Tea, Coffee, Beer, Coke etc… I wonder if the benefit from amount of fluid we get from them is bigger or smaller then the handicap of dehydration. In other words it is worth to drink them if we want ...
1
vote
1answer
64 views

Why are bald heads are so “shiny”?

Why do males with baldness have shiny skin on their head, whereas we don't experience such "shiney skin" in other parts of body without hair.
1
vote
1answer
17 views

Neuron activity on body parts measurable?

Is it possible to measure the neuron activity on body parts like the back or the arm? Or is this done already? Of course neuron activity can be measured on the scalp using an EEG. I wonder if similar ...
1
vote
1answer
71 views

What is the evolutionary advantage of having pubic hair?

Only humans have pubic hair. What is the evolutionary advantage in having it?
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0answers
37 views

how to build a PPI network? [closed]

I would like to know how to visualise a cluster of several proteins lets say I have a list of proteins ...
3
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1answer
12k views

Why do we suffer abdominal pain after we get very angry or stress?

You also realize probably, when we get so much anger or high levels of stress, after some point we have terrible stomach ache, like really heavy pain. Why is that? How stress or anger can effect our ...
4
votes
2answers
127 views

Can the human body create glucose out of fat?

I read conflicting views about whether or not the human body can create glucose out of fat. Can it?
2
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0answers
113 views

Cause of a extra vertebra in the human body [closed]

Most people have five vertebrae in their lumbar (lower back) region, which are named L1 to L5. However, some people possess an additional lumbar vertebra located below the L5. This extra vertebra, ...
2
votes
1answer
104 views

Why did we evolve to control our breath?

I had this question in my mind and tried to think of why we would evolve to be able to control our breath. I remembered the Aquatic Ape Hypothesis, which makes a lot of sense and would explain it, ...
1
vote
1answer
30 views

Are there known functions of AST, ALT, and amylase in the blood?

A number of enzymes can be measured in the blood or plasma that aid in the diagnosis of certain diseases. For example, patients with particular liver diseases may have elevated aspartate ...
0
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0answers
25 views

How does the human stomach handle a mix of digested and undigested food?

As I understand it, the stomach digests the bolus into chyme and then passes the latter on to the small intestine. This process takes between 40 minutes and a few hours. But what happens when the ...
1
vote
1answer
123 views

Which are the last cells of the human body to die?

When somebody dies, which are the last surviving cells of his/her body? Those of hair, nails, or some other obscure but resilient cells? Shedding light on why and how they are so vital might boost ...
5
votes
4answers
8k views

Why can't ciliary muscles in the human eye relax like other muscles?

I had laser eye surgery a decade ago, but in recent years my eyesight has become significantly myopic. I consulted an ophthalmologist to see if this was eye strain because I work at computers a lot, ...
1
vote
1answer
38 views

Human Demography - Where can I find this statistic?

In "An Introduction to Genetics" by David J. Merrell, copyright 1975 by W.W. Norton + Co., p. 742, in the Chapter "Genetic Counseling and Eugenics," the author states: "... 50% of the women produce 85%...
17
votes
2answers
545 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 ...