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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2
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1answer
30 views

How are cardiac cells stimulated by an action potential?

Why, and how, does the action potential of one cell in the heart stimulate an action potential in the next cell? I'm interested in an answer with citation.
3
votes
1answer
148 views

Why do people in the scientific community use terminology such as renal, hepatic, cardiac instead of kidney, liver and heart? [closed]

Are there differences between renal, hepatic, cardiac and kidney, liver and heart? Is the "jargon" used more commonly because of tradition, or is there some definitive biological basis to it?
2
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2answers
66 views

Blood draw from the elderly or those with tiny veins

A lot of people have very small veins making it next to impossible to draw blood. Would a nitroglycerin tablet (or some other vasodilator) before drawing blood help to enlarge veins?
3
votes
0answers
32 views

Why are kidney discard rates so high?

A recent report from UNOS states: The kidney discard rate has returned to pre-KAS levels, dropping from 20.2 percent in the first six months to 18.4 percent in months 7-10. To me, this seems ...
3
votes
3answers
222 views

Can/Have cancer cells be/been used in stem cell culture lines?

Since Cancer cells have unlimited growth potential, can they be induced towards totipotency and pluripotency? If so, can cancer cells be used in stem cell culture because of similar properties of ...
1
vote
1answer
24 views

How does increased heat increase the rate of metabolism?

I have heard that taking a hot shower helps blood circulation metabolism. For (2) metabolism, I think that the rate is increased since kinetic energy is given to compound to bond with enzymes ...
2
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0answers
11 views

What are necessary parameters for a tissue scaffold to be biodegradable?`

I am a mechanical engineer with little biological experience, but I have recently been looking at tissue scaffoldings. My current understanding is as follows, but may be flawed. I would appreciate ...
3
votes
2answers
33 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 ...
0
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0answers
24 views

Why doesn't EMG data for triceps show a clear relationship?

In a surface electromyography (EMG) experiment of the triceps muscle where a person lifts weights, I found the value for maximum amplitude of EMG signal to be rather similar for all loads of 0-10kg. ...
0
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0answers
15 views

What will happen if an anaplastic/cancer cell is used in cloning?

Since anaplastic cells have high glycolytic ratio and replicative potential, if they are used as the somatic cell in a model of cloning(like dolly's mother's udder cell), what is likely to happen?
0
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1answer
65 views

What's the difference between tumor cells and host cells? [closed]

When you talk about cancer, is there a difference between tumor cells and host cells ? What is the role of immune cells ? in a nutshell ?
7
votes
2answers
206 views

Does knowing the sex of each of a couple’s first N children have any marginal value in predicting the sex of child N+1?

Does knowing the sex of each of a couple’s first N children have any marginal value in predicting the sex of child N+1? By “marginal” I mean predictive power beyond other known effects, e.g., the race ...
1
vote
3answers
80 views

Are missing limbs hereditary?

So with my basic understanding of biology, DNA can change over time. Does this mean that if one (or both) parents have something major missing (like a limb), the kid will come out without a limb? ...
6
votes
1answer
75 views

How pronounced is the difference if we would change the running direction for runners?

I was jogging when I asked myself this question: In running contests the standard running direction is counterclockwise; I also believe to remember that the regulation is very old (right back to the ...
1
vote
1answer
73 views

Is intelligence (or mental ability) genetically transferred (inherited characteristic) from the parent to the offspring or is it an acquired trait?

The question is simple- whether our mental ability i.e. ability to acquire and store knowledge and comprehend and analyse the stored bits, an inherited trait (i.e. genetically transmitted from the ...
2
votes
0answers
51 views

Why did humans evolve the ability to feel such a high level of heat pain? [closed]

It's probably because our ancestors were frequently around 300°C metal which badly damages flesh in a fraction of a second because they made fires to cook. I don't see why that would cause natural ...
2
votes
3answers
63 views

Do adult humans exchange beneficial bacteria? If so, how?

Recently there has been increasing interest and research into symbiotic bacteria present in humans and human gut. I'm aware of two new discoveries: humans are surrounded by a unique cloud of ...
17
votes
2answers
45k views

How many human cells are there in our body, on average?

How many human cells are there in our body, on average? Wikipedia says 1013: Bacterial cells are much smaller than human cells, and there are at least ten times as many bacteria as human cells in ...
29
votes
3answers
3k views

How could humans have interbred with Neanderthals if we're a different species?

To be clear, I'm not doubting that homo sapiens and homo neanderthalensis did interbreed: of that much I'm convinced. Within the past few years I've seen an upcropping of pop-sci articles discussing ...
0
votes
1answer
54 views

What is the normal blood water content

What is the normal water volume per 1 L of blood, and how much deviation from that norm causes dehydration or hyponatremia?
2
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0answers
40 views

Why do workouts cause your muscles to feel heavy?

I know that muscle activity causes your muscles to build up lactic acid. Is this the specific reason that your muscles begin to feel heavy? How does this relate to the healing or inflammation process ...
0
votes
1answer
82 views

Are human teeth only diphyodont or both diphyodont and monodont?

Many books say human teeth are only diphyodont .But premolars appear only once and one molar appears later which should be considered monophyodont. Dental Formulae : CHILD - 1. Incissor -2/2 2. ...
4
votes
3answers
2k views

What is the minimum air pressure the human body can tolerate if oxygen supply is not an issue?

Disregarding hypoxia, what is the minimum air pressure that the human body can tolerate? (i.e. at what air pressure would the blood start to boil, or skin start to burst, or whatever else might ...
5
votes
2answers
170 views

Does soap kill human cells?

I see many products, particularly hand soap and cleaning products, that claim to kill 99.9% or more of bacteria. This makes me wonder, if the chemicals are potent enough to break down bacterial cell ...
1
vote
1answer
58 views

When you blow through your nose while holding it closed to “depop” you ears, why do you sometimes feel it in your eyes?

After your ears have "popped", for example on a flight, I heard you are supposed to hold your nostrils closed and blow through your nose to readjust the pressure to the normal level. Why do you ...
1
vote
1answer
95 views

If all bacteria in human gut are dead, can they be there again?

If someone likes to eat chocolate, she may have gut bacteria which like chocolate according to some articles that I have read. ...
5
votes
2answers
751 views

What is the maximum number of babies a human woman can have?

I know you could divide the female fertility period (~40 years, right?) by 9 months which would give something like ~50 kids (with no multiple kids per pregnancy). The limiting factor in this ...
0
votes
1answer
54 views

Why are lipid-soluble substances harder to excrete?

I understand why water-soluble substances can be excreted. However, why are they easier to excrete than lipid-soluble substances? Why can’t lipid-soluble substance be excreted just as easily in the ...
2
votes
1answer
100 views

Why is chromatin not condensed during interphase but is in prophase [closed]

Cell cycle goes through three processes: Interphase Mitosis Cytokinesis Why are chromatins not condensed during interphase but instead condensed at prophase of mitosis? What makes them condense ...
1
vote
1answer
45 views

Movement of sperm to the egg

Sperm swims through semen and reaches the haploid egg in the oviduct during fertilisation. Once the sperm reaches the cervix, through what does the sperm swim through to reach the egg? Is the ...
2
votes
0answers
43 views

Proteases in the blood

I’m reading on hormones and the book talks about how peptide or amine hormones are easily broken down by proteases present in the blood plasma. This has led me to question the interactions between ...
11
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2answers
537 views

Is global life expectancy normally distributed?

I am trying to find out what the world distribution of life expectancy looks like.
7
votes
2answers
4k views

What did we learn with Nazi human experimentation?

Was there actually any useful knowledge gained from the Nazi experiments on human test subjects? Wikipedia cites freezing and phosphine gas reactions, but I would like to know other potential results ...
2
votes
1answer
85 views

What is the difference between Amino acids from blood and urine?

I would like to understand the difference between different tests for Amino Acids. Any blood laboratory offers amino acids tests using 3-4 methods Blood serum Urine Random Urine 24 hour (all the ...
2
votes
2answers
127 views

Why is warm water comfortable, but warm air uncomfortable?

I friend of mine tried floating, where you lay in a bath kept at body temperature (98.6 degrees F). He said after a while you don't feel the water at all. This made me wonder why being in warm water ...
1
vote
0answers
86 views

Does Acromegaly cause actual expansion of the zygomatic(cheek) bone

Acromegaly is a disorder in adults involving excess growth hormone production. Since epiphyseal fusion has already taken place in most bones of adults , this does not cause an increase in stature. ...
1
vote
1answer
80 views

Does dairy negatively affect the voice for singing?

Singers and actors are warned not to consume dairy, primarily milk, before a performance. From personal experience, I know that this is a very valid warning. It is commonly assumed that this is due to ...
9
votes
1answer
23k views

What is the normal duration of human sexual intercourse?

Wikipedia is saying: Men's typical ejaculatory latency is approximately 4–8 minutes How the researchers measured this? How did they know if the test subjects weren't suffering from premature ...
5
votes
2answers
906 views

Do we need to drink less water in humid weather than in dry weather?

From my understanding, humid weather means that the air has a lot of water in it. Therefore, someone who lives in this kind of weather would be hydrating himself just by breathing. Does that mean ...
0
votes
1answer
16 views

Absorption of Topical Magnesium

Can Magnesium be absorbed through the skin? Some athletes believe that Homeopathic magnesium lotions can reduce muscle pain. I've tried this and it doesn't work nor can I see how it can.
0
votes
1answer
83 views

Why Do we close our eyes while sneezing?

Google says germs may fall on eyes from our sneeze but it happens all the time . Also it says it a part of contraction. What may happen if we sneezing wirh our eyes open ?
9
votes
1answer
4k views

Effects of Polyphasic vs Monophasic sleep in humans

Why do humans practice monophasic sleep cycles? When altering one's circadian rhythm to a Polyphasic sleep schedule, how much would that affect development? Is Monophasic sleep (once per day) ...
3
votes
1answer
6k 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, ...
3
votes
1answer
97 views

Why is one testicle larger than the other?

Why is one testicle generally larger in humans? Just due to asymmetric development, or is there a hypothesis as to some utility it serves? I read that the different heights may be attributed to ...
3
votes
1answer
86 views

How late in a human pregnancy can a zygote split?

This page indicates that the first two days is "very early" for a zygote to split, and that conjoined twins are the result of an "extremely late" split: If the zygote splits very early (in the ...
0
votes
2answers
54 views

When did human ancestors learn to walk? [closed]

Where does our ancestor learn to walk from? How do we control our legs whenever we take a step? I confuse every time whenever I take one step.
33
votes
6answers
1k 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 ...
3
votes
2answers
5k views

Possible genotypes for blood types?

If I am blood type B, what are all the possible genotypes that could be expressed by my parents? I think it might be 16 but I was reading online and saw this: Similarly, someone who is blood type ...
2
votes
1answer
25 views

Can specific B-cells be created in a lab? [closed]

Instead of creating protein sequences, could that stepped be skipped and just have B-cells created to manufacture a particular type of immunity?
4
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1answer
68 views

Is it easy to test human Flicker Fusion Threshold?

How would you go about testing human flicker fusion threshold? Is the testable rate consistent in humans over time or volatile?