226 Answered Questions for the topic human biology

04/16/19

Why does sympathetic activity constrict pulmonary vessels?
I don't know understand why sympathetic stimulation constricts pulmonary vessels? I thought that the sympathetic nervous system activated the body for physical activity. Physical activity would... more
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04/16/19

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... more
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04/11/19

Human perception of time depending on age?
From what I can tell and what thus far all people with whom I discussed this subject confirmed is that time appears to "accelerate" as we age.Digging a little, most explanations I found basically... more
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04/11/19

How does drug-induced photosensitivity work?
Some drugs (tetracyclines, for instance) can cause photosensitivity reactions—that is, some patients become extremely sensitive to the sun, developing rashes or inflammation after spending time in... more
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Human Biology Biology Bacteriology

04/10/19

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.... more
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Human Biology Biology Statistics Genetics

04/10/19

What is Mendelian Randomization, and how is it used to infer causality in epidemiology?
Studies of human traits and diseases are inherently confined to observational studies, known as epidemiological studies. This can make it very hard to determine what actually causes a particular... more
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04/10/19

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... more
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Human Biology Genetics Twins

04/10/19

Do identical twins have the same fingerprint?
When there is every thing same from their genes to their phenotype so then why they don't have same fingerprints?
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Human Biology Pharmacology Brain Toxicology

04/09/19

Influence of alcohol on brain cells?
As far as I know, drinking alcohol is killing cells in the brain. But is it linear? E.g. if I have 1.0 per mil and it kills 1000 cells will 2.0 per mil kill 2000 cells?
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Human Biology Biology Psychology Nutrition

04/04/19

Why is it advised that infants are fed mother's milk?
I have heard that mother's milk is preferred over other baby foods, because it contains immunoglobulins (secretory IgA), and other essential nutrients. But why is mother's milk so special? Any... more
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Human Biology Biology Death Pain

04/02/19

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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04/02/19

What actually happens when my leg 'falls asleep'?
Most people have experienced the temporary loss of feeling and tingling in their leg resulting from sitting in an abnormal position for a short while. Usually you get a loss of feeling in your leg... more
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03/29/19

Are we able to determine the full genotype for the dominant trait?
Are we able to determine the full genotype for the dominant trait?
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03/28/19

If a human takes antibiotics are all bacteria in the body killed?
From my basic understanding, antibiotics kill living things, bacteria for example.Do the antibiotics consumed by a human-being distinguish between what they kill? Or do they just kill every... more
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Human Biology Biology Genetics Hematology

03/27/19

Origin, or source, of rhesus negative in human blood?
This is my first post here, so please be gentle. I recently learned that I have Rh- blood (I'm A-), and was idly looking into blood types on Wikipedia. I was surprised to find that relatively few... more
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Human Biology Genetics

03/27/19

What makes a cancer contagious?
Most human cancers are not (very?) contagious (perhaps besides a couple of incidents). But the Tasmanian devil seems to have a form of cancer which is contagious. Now what makes the difference... more
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Human Biology Microbiology

03/27/19

Do probiotics survive digestion?
Pretty much this. I've been wondering if any of the yogourt and other "health" foods containing living probiotic cultures survive digestion to populate our intestines? If so, is there peer-reviewed... more
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Human Biology Genetics Hematology

03/27/19

Origin, or source, of rhesus negative in human blood?
I recently learned that I have Rh- blood (I'm A-), and was idly looking into blood types on Wikipedia. I was surprised to find that relatively few (~15% of all) humans have it, and most of those... more
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Expert Answers •1
Human Biology Genetics

03/27/19

Athletes: nature vs. nurture?
Having watched a lot of olympians the last few weeks, I was struck by how many of them have actually spent their wholes lives/careers training for their one event (be in running a marathon, or... more
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03/27/19

Why do vaccines cause your arm to hurt?
When you get a shot for a vaccine (for example, the annual flu vaccine), the nurse frequently indicates that your arm will ache for a day or two, maybe more. This ache is typically not just a pain... more
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Human Biology Biology Physiology Medicine

03/27/19

What causes swelling after impact?
Why does the head swell after getting hit by something hard? What is the liquid that forms after impact?
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Human Biology Language Biology Terminology

03/26/19

Is there a specific suffix for "within a cell"? i.e. in a similar manner to how -aemia refers to within the blood?
Words like hyperglycemia and hyponatremia refer to the relative level of each component in the blood, not in the cell. Is there a suffix for within the cell? For reference I would like one word as... more
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Human Biology Pharmacology Neuroscience

03/26/19

Can neurotransmitter depletion cause short-term drug tolerance?
**I'm curious to know if neurotransmitter degradation factors into drug tolerance and neural conduction and, if so, to what extent.** As I recall from textbooks I read as an undergrad, one... more
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03/26/19

Where does the 'C' in exhaled CO₂ mostly come from?
When a human being exhales CO₂, what is, by the numbers, the main source of carbon atoms exiting the body in this way? I mean what class of cells, or which tissues are the biggest on a pie chart of... more
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03/26/19

Do men and women have the same number of genes?
As far as I know, humans have 23 pairs of chromosomes, each one which contains a particular amount of genes. But in the "last" pair, men have a XY pair chromosome, and women have a XX pair... more
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