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Questions tagged [human-biology]

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 votes
2 answers
2k views

Shouldn't evolution have taken care of baldness already?

It is my understanding that the hair on the head is there to protect us from sunburn. I've never seen a bald animal, so isn't evolution in charge of addressing these type of things? How is it that ...
1 vote
0 answers
40 views

Does succinic acid provide any caloric value in humans?

Would the ingestion of pure succinic acid provide any caloric value in humans? I couldn’t find any nutritional information about it via Googling, but I read on Wikipedia that it’s converted into ...
4 votes
2 answers
1k views

The arrangement of retinal cells?

The section of retina shows a layered arrangement of the various retinal cells. Starting from the inside (where the light strikes first) is the nerve fibre layer, ganglionic layer, amacrine cell layer,...
6 votes
1 answer
106 views

Human biology - liver regeneration after laprascopic segmentectomy

I am trying to understand to what extent human patients can regenerate liver mass after laprascopic segmentectomy: what part of liver will be regenerated and how fully. My work with sources is not ...
-3 votes
1 answer
250 views

Could a bearded woman ever become pregnant?

I am referring to woman who are facing Hirsutism. So I gone through Hirsutism, there is no mention of pregnancy. So could a bearded woman ever become pregnant ?
3 votes
1 answer
687 views

Why can't humans digest dietary fiber when we can digest starch?

So, I can see that there's a couple of questions touching on this subject already, but none of them answer the aspect that I'm curious about: Dietary fiber is a polymer composed of multiple starch ...
14 votes
4 answers
46k views

Will the heart keep beating if it's separated from the body?

The heart is a vital organ in our body, as it drives blood circulation. I was wondering if a heart keeps beating if it is separated from the body? If yes, then why?
5 votes
3 answers
460 views

How do I know if the claims of a scientific paper are generally accepted?

I am looking for information about the use of glucosamine and chondroitin for treatment of back pain and disc degeneration. A paper published in Military Medicine in 1999 reported some beneficial ...
12 votes
1 answer
3k views

Evolutionary reasons why you cannot tickle yourself but you can masturbate

There are obviously good reasons that explain why you cannot tickle yourself (see e.g. here). This got me thinking why it is possible to masturbate... Wouldn't it make more sense to not be able to do ...
-2 votes
1 answer
2k views

Is that true that plant stem cells can be used in humans?

I was reading an article (which seems very fake to me) on sensitive topics, but there was one astonishing statement: Stem cells are obtained from certain plants that grow all over the world. Once ...
24 votes
4 answers
35k views

In Japan, the official average body temperature is 36.0 °C. Why so different from that of Europe?

The Japanese Wikipedia states that the average human body temperature is 36.0 °C (here,"ヒト"). The statement references the data from the Japanese government. Actually all of my Japanese friends think ...
1 vote
3 answers
127 views

How can you diagnose albinism in a naturally light-colored person? [closed]

Not all albinos have white hair. There is a type of albinism where the affected person has light yellow hair and the skin color can be the same as a normal North European person. How can you diagnose ...
6 votes
1 answer
361 views

What is the function of dihydrofolate reductase in humans?

According to StatPearls, synthetic folic acid — as an artificial dietary supplement — needs to be converted into the active form tetrahydrofolate (THF) by dihydrofolate reductase. In the cells, folic ...
15 votes
2 answers
12k 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 ...
2 votes
2 answers
122 views

Why does damage to myelin sheath in multiple sclerosis lead to a decrease in information reaching the brain from sensory receptors?

In multiple sclerosis(MS), myelin sheath is attacked and damaged. When this happens, there is a decrease in the amount of information reaching the brain from sensory receptors. How and why does a ...
8 votes
2 answers
1k views

Does human digestive system benefit from eating same kind of food consistently?

Here's the reason why I'm asking: I've heard that it takes some time for pets(cats/dogs) to adjust to a different dry feed, where the new feed has to be mixed with the old one, slowly replacing the ...
2 votes
2 answers
1k views

How does UV light damage the DNA when the chromosomes are deep inside the cell?

When UV light falls on the skin it has to go through the cell membrane and the nuclear membrane to reach the chromosomes. So it looks like that the DNA is protected but it probably isn't. Won't ...
1 vote
0 answers
96 views

Why does a respiring mitochondrion have less cristae?

I read the following- Number of cristae is more in resting-state of mitochondrion, but decreases with activity, hence less in the respiring state. cited: GK Pal, Textbook of Medical Physiology ...
4 votes
2 answers
2k views

Why do humans lose subcutaneous fat tissue with age?

Why exactly do humans lose subcutaneous fat tissue with age? It appears that we either lose fat cell volume or we might actually be losing the number of fat cells with age. One hypothesis is that as ...
2 votes
1 answer
257 views

Is Pars intermedia functional in humans?

My textbook says, "Pars intermedia secretes only one hormone called melanocyte stimulating hormone (MSH)." My teacher says that in humans MSH is secreted by the anterior lobe because the ...
1 vote
1 answer
150 views

Monozygotic vs Dizygotic heteropaternal superfecundation

Update: I had a wrong assumption. After triple checking, I now see that how ordinary monozygotic twins arise is 1 sperm and 1 ovum and then later the zygote splits up. (1.1. and that that phil and ...
0 votes
0 answers
79 views

Is the human mouth more burn-resistant than other animals which don't eat cooked food?

I burnt my mouth on some hot pizza and it got me wondering if we have been eating cooked food long enough to have evolved a better resistance to oral burns than other species. Have there been any ...
4 votes
1 answer
53k views

A strand of my hair has a grey section in the middle, how is this possible? And why does it happen?

My hair is usually brown and black, I haven't dyed my hair for two years and if I had this would be strange. A strand of hair went from black(roots) grey (middle) then light brown(bottom). How does ...
2 votes
2 answers
36k views

What is inside the male’s body in the space where females have the ovaries and the uterus?

The male penis and scrotum are external, whereas the female sex organs are placed "inside" the body. As females have the bladder, rectum etc. just like males, does this mean overall females ...
2 votes
3 answers
288 views

Is it true that ethanol can have some positive effects?

I recently was reading this inforgrafics about excessive alcohol use. It is written: No one should begin drinking or drink more frequently based on potential health benefits I am surprised. Is ...
1 vote
1 answer
87 views

My bathroom connected scale pretend telling me my total body water level? How could it do that?

Along with a connected watch, I also bought a connected bathroom scale. Both are giving me plenty of indicators, very extended ones. And sometimes, I wonder where and how they can extract or deduce ...
1 vote
0 answers
154 views

difference between proximal and distal mechanisms of aging in biogerontology?

In his book Biology of Aging, Roger McDonald describes the difference between causes and mechanisms of aging; and states that the cause of aging is essentially thermodynamic (entropy) and that ...
13 votes
5 answers
22k views

Why is the opposite of plantar flexion called "dorsiflexion"?

Why is the action of flexing the foot so that the toes move anteriorly/superiorly (i.e. in the direction opposite that which they move during plantar flexion) described as "dorsiflexion?" In the same ...
2 votes
1 answer
350 views

Why does water damage the lungs but amniotic fluid doesn't?

I've read that near-drowning causes lung damage due to water inhalation. How come this is not the case with amniotic fluid? Taking this further, would lukewarm purified oxygenated water cause damage (...
94 votes
6 answers
38k 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 ...
5 votes
2 answers
2k views

How does fever physically work?

What is the physical mechanism that causes temperature to rise during a fever? I know that somehow the hypothalamus "orders" to increase the standard body temperature regulation, and this should ...
4 votes
2 answers
1k views

What specific interaction between methylphenidate and quetiapine causes toxicity concerns?

A number of reputable sources on drug interactions posit a potential interaction between methylphenidate and quetiapine, described on Medscape as follows: quetiapine increases toxicity of ...
4 votes
2 answers
2k views

What advantage does the pseudostratified epithelial structure type provide over squamous, cuboidal, and columnar?

I'm currently and have had difficulty receiving an answer about the role the pseudostratified columnar structure provides. I understand that that the following have their respective advantages: ...
3 votes
2 answers
102 views

Are there any biometrics that can measure tiredness (sleepiness)?

Are there any biometrics that can estimate how tired someone is? I specifically refer to tiredness in the sense of sleepiness (as opposed to physical tiredness that might happen after a workout, for ...
1 vote
3 answers
26k views

What is the function of E. coli bacteria in the human gut?

What is the function of the bacterium, E. coli, in the human gut? I have tried to find the answer by searching the Internet (e.g. here), but have been unsuccesful.
1 vote
1 answer
26 views

Does a tubular sodium reabsorption cause a stimulation of β2-adrenergic receptors?

I read the study "The Role of Aldosterone in Obesity-Related Hypertension" and there is one thing I didn't understand. They write: "According to norepinephrine-induced tubular sodium reabsorption, ...
2 votes
1 answer
4k views

Does drinking dry water have same effect as drinking regular water?

Dry water consists of water droplets that have been coated with silica nanoparticles, which prevents the droplets from forming a liquid. If a human swallows dry water, does it have the same effect as ...
1 vote
0 answers
57 views

What is the true response of human photoreceptors to different wavelengths? Why is there so much disagreement in the literature?

I can find several qualitatively different diagrams of the responsiveness of human cones and rods to different wavelengths of light. A page referencing Bowmaker and Dartnall, 1980 has the following ...
8 votes
3 answers
8k views

Can a human smell through the ears?

The title does, prima facie, appear absurd. Performing a swallowing action whilst pinching the nostrils shut gives the impression of listening through a bucket filled with water around the head; ...
0 votes
0 answers
231 views

Does cancer really remain undetected about 80% of its life?

I was reading Atomic Habits by James Clear, who mentioned this and decided to google it. The only mention of this at least in the first search page was from this source from February, 2012. Is there ...
5 votes
2 answers
12k views

Wim Hof Method claims Alkaline Blood is Good. Contradictions? Counterproof?

The Wim Hof Method claims, that it is beneficial to have alkaline blood. On the other site there is the medical claim that if the pH-value is not within the range of 7.36 – 7.42, enzyms are ...
3 votes
0 answers
86 views

Sexual devolpment and sexual organs in humans

In an anatomy book from a friend studying medicine (Netter's book), I looked at some elements of sexual development in embryos. From a developmental stance, we can draw some analogous organs that ...
1 vote
2 answers
203 views

What is the connection between LDL, liver, and saturated fat?

I've been trying to learn about cholesterol, lipoproteins, and fats, but unfortunately, there is an ocean of confusing information on the internet. I don't have any solid background in biology, so ...
6 votes
3 answers
347 views

What is the purpose of the adrenal medulla?

The adrenal medulla is less of a 'real' endocrine organ like the others in the endocrine system and much more an extension of the sympathetic nervous system. In fact, its chromaffin cells are modified ...
3 votes
2 answers
2k views

What controls the size of breasts?

I am not a biology student, just a curious person. To be specific, I'm talking about female humans. I know that it might apply to other mammals. What controls the size of breasts? I have heard about ...
9 votes
2 answers
619 views

Do breasts size depend solely on fat amounts?

I've read the first answer here on quora and it suggests that (not during pregnancy and breastfeeding) breasts differ in size only due to the amount of fats. However, there can be firm or soft breasts ...
18 votes
3 answers
2k views

What is the cause that angina pectoris is felt in your left arm?

When someone has heart problems sometimes they feel pain in their left arm. But why is the left arm painful?
5 votes
1 answer
2k views

Chest muscle and female breast size

Do female chest size have anything to do with muscle? I know many female athlete and their average breast size is much bigger than normal female that does not tend to play sports. Do this have any ...
0 votes
0 answers
99 views

If x amount of a chemical starts to become harmful for a mice, then will 3000x amount of it start to get harmful for a human (3000 times heavier)? [duplicate]

My reasoning is simply that since human beings are 3000 times heavier than mice, the safety threshold for exposure to a chemical should be approximately 3000 times higher for human beings as compared ...
5 votes
1 answer
285 views

What are the Genes/Enzymes responsible for the supposedly stark between-individual differences in lethargy after eating starches?

Andrew Huberman claims in one if his podcasts episodes that: [...] because starches cause the release of serotonin in the brain and lend themselves to a state of sleepiness. Now, I should mention ...

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