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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8
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1answer
2k views

Can a human acquire a memory of an animal? [closed]

I would like to know if it's possible for a human to acquire an animal memory. I mean, animals store their memories in their brain, right? And so do we, humans, store our memory. So, is it possible ...
5
votes
1answer
275 views

Effect of closed eyes on balance?

Suppose you want to stand on one leg. Doing it eyes open is not that difficult, but doing it eyes closed seems to be difficult. Why?
8
votes
1answer
1k views

Do the right-handed people tend to use the right side teeth of their jaw to chew food more often than the left-handed people?

And vice versa, do the left-handed people tend to use the left side teeth of their jaw to chew food more often than the right-handed people?Or the frequency of food chewing distribute fairly to both ...
2
votes
1answer
1k views

Why can't people talk while inhaling?

Why do we have to exhale in order to talk? From looking on Wikipedia, it seems like it has something to do with the glottis, but I'm not clear on the mechanism that makes speech sound so different ...
1
vote
1answer
49 views

Anesthetics, specifically inhaled anesthetics

I have had a look at previous inhaled anesthetics and many of them appear to be fluorocarbons. What could be the mechanism behind fluorine's anesthetic properties? Is it the specific bonding pattern ...
9
votes
3answers
733 views

What causes feeling of feet falling asleep to be delayed?

This answer explains the sensation of extremities "falling asleep" as a result of sustained pressure on a nerve. The answer links to an external web page that says that the feeling "quickly goes away ...
0
votes
1answer
64 views

How can Pyridostigmine have the indication of Myasthenia?

I am thinking how pyridostigmine can be used in the treatment of myasthenia gravis. Its similar compound (neostigmine) is also anticholine esterase. This compound has the indication of myasthenia ...
1
vote
1answer
217 views

How does anger relate to blood pressure?

Anger is an emotion generated by neural processes in the brain and is associated with elevated blood pressure. How can an emotion, which is totally related to brain, result in blood pressure changes?
12
votes
2answers
2k views

How was birth control realized in ancient days? [closed]

In ancient days, there were no birth control methods like condoms or contraceptive pills available. How did they control pregnancy?
2
votes
1answer
189 views

How to manage fat-gluten oxidation in celiac disease?

Assume you have been in non-gluten diet 20 years. You built mass 8 mass with substances containing gluten (endogenous gluten stored in fat). Then, celiac disease is diagnosed. You have been 3 ...
-1
votes
1answer
87 views

To understand side-effects for nebivolol's beta1 selective pathway in PubChem? [closed]

Assume you have a drug nebivolol. When nebivolol is used as beta1 selective drug, beta2 is mostly for side effects, but this is not clear from PubChem. I do not know any cases where nebivolol is used ...
1
vote
1answer
74 views

Clonidine's adrenonergic nature?

I am little confused here. I used the term adrenoagonist and sympatholytic to describe the compound. However, my teacher says that the correct term here is adrenomimetic -term. My understanding of ...
3
votes
1answer
3k views

After vasectomy, where does the sperm go?

After vasectomy, where does the sperm go? Vasectomy Procedure cuts only vas deferens, But Our Testes still produces sperm, if there is no output for sperm, where does it go?
3
votes
2answers
1k views

Why do humans have only two nipples?

If other animals have more than 2 nipples, then why do humans have only 2 nipples? Even my pet dog has more than 2 nipples.
2
votes
3answers
537 views

Is there a stem cell/ biogel method exist for muscle and tendon lengthening?

Is there a stem cell/ biogel method exist for muscle and tendon lengthening? It is known that height surgery is limit to six inches with two surgeries and three inches each, it is also true that ...
0
votes
1answer
6k views

What is the exact chemical composition of human body? [duplicate]

I've just watched Breaking Bad Season 01 Episode 03. In that Walter gives the chemical composition of human body. The conversation is as follows Walter White: Let's break it down. Hydrogen. What ...
5
votes
1answer
533 views

Why does hair thicken and become more rough after a razor shave but not after one using a trimmer? [closed]

If a razor cuts only the hair, then how does hair thicken and become more rough with a razor shave and not after one using a trimmer? If both are used for hair removal, why is there a difference in ...
5
votes
3answers
307 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 ...
10
votes
2answers
161 views

How Circumcision could reduce the chance for a HIV infection?

Circumcision removes the foreskin of the penis which mainly acts as a cover to the penis. Normally removing the foreskin makes more vulnerable to any STD, so how could circumcision reduce the risk of ...
4
votes
1answer
119 views

Does transplanted heart have full sympaticus without medication?

I am reading this and this where I am considering this sentence [N]o baseline parasympathetic innervation [in transplanted heart]. Does this sentence imply that the heart work then in full ...
5
votes
2answers
378 views

How do gory images lead to nausea?

How do gory images lead to nausea? Yesterday my friend visited shock sites (a website). He said that he got nauseous sensation within seconds after viewing the gory images. However, I don't ...
5
votes
1answer
601 views

In males, why it is difficult to control orgasm?

Why it is difficult to control orgasm in male humans? How are orgasms controlled and what is different between males and females? We can control urine for few minutes, but we can't control orgasm for ...
6
votes
1answer
7k views

Is it biologically possible for an adult's eye color to change?

Can it be that the adult eye can change color? Specifically my question is about a unilateral color change, such that the color of one eye remains constant, while the other changes color over time. ...
0
votes
2answers
38 views

T-cells Question

T-cells are important for efficient vaccination since they have: A. T-cell receptor (TCR) B. CD4+ C. CD8+ D. Memory My gut is telling me it's A since the TCR would recognize the antigens but I ...
0
votes
1answer
66 views

Exact location of E. coli in human body

E. coli lives in lower intestine. But exactly where can we find E. coli, and where is there none (or a really small amount) of it? I need the exact names of parts of the lower intestine where we can ...
0
votes
1answer
46 views

Ephedrine or pseudoephedrine indirectly central alpha2 mimetic?

I started to think this problem by first thinking if the alpha2 mimetism is possible in either case. It seems to be indirectly in either one. Ephedrine seems to have more prominent effect in CNS. ...
1
vote
1answer
47 views

Is Norepinephrine beta2 adrenomimetic?

I know that it has alpha1, alpha2 and beta1 effects. It has beta2 receptor where epinephrine can effect. However, to say that it is beta adrenomimetic, I am not sure. That is ligand binding beta2 ...
0
votes
1answer
112 views

How can succinylcholine cause myorelaxation?

I first thought that this is because of prolonged depolarisations. However, I am not sure anymore, because after reading PubChem, the only possible pathways are are Choline agonist. So I would say ...
5
votes
1answer
2k views

Like other animals, why humans don't have species & breeds?

Like other animals, why don't humans have species & breeds ? Even my pet dog is one type of breed, but we (humans) lack breeds & species? What is the main reason?
1
vote
0answers
26 views

What's the max speed that humans could run? [duplicate]

Assuming humans could use all of their muscle strength at once, with no need of cooling or energy, how fast could we theoretically run?
2
votes
1answer
4k views

Why do people and animals stretch out their bodies and what is causing this behaviour?

I noticed that my cat which is only 6 months old has started stretching its body from time to time. Then I thought that this motion doesn't seem very natural from another cat's viewpoint, so my cat ...
0
votes
1answer
89 views

Safe level of chlorine in water [closed]

Chlorine is usually mixed in water to make it safe for consumption. What is a safe quantity of chlorine that can be consumed? What are the side effects of chlorine and does this include hair loss? ...
11
votes
6answers
3k views

What is the use of eye banks, if eyeball transplants do not exist at present?

Corneas are donated and transplanted, but not the eyeball. I don't understand. What is the purpose of donating a cornea without an eyeball to a blind person?
3
votes
0answers
81 views

What is the biological basis of “energy” that extraverted humans draw from social engagements and introverts expend?

This question is related to this question about introverts becoming exhausted after extended social events on cognitive sciences stack exchange. As I read more on the topic of human extraversion-...
3
votes
0answers
94 views

What proportion of salt in water would make it not dehydrate nor hydrate someone? [duplicate]

Drinking sea water can be deadly as it contains too much salt, basically de-hydrating the body. Normal tap water contains little salt and is good for re-hydration. My question: How much salt needs to ...
11
votes
2answers
1k views

If human eyes watch an area, what's the shape of its capturing shape? Rectangular? Half spherical?

A normal camera can capture a rectangular image. If human eyes watch an area, what's the shape of the captured region? Rectangular? Half-spherical?
1
vote
0answers
437 views

How does proximal centriole of human sperm function?

I've read that the human's unfertilized oocyte ( stuck at metaphase 2 of meiosis ) lacks centrioles and that it completes meiosis 2 after fertilization as sperm gives its proximal centriole. Then what ...
9
votes
0answers
596 views

Evolutionary reasons why you cannot tickle yourself but 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 being able to ...
3
votes
1answer
101 views

How does the body really react to exposure to the vacuum of space?

I've seen sci-fi movies where the effects the body being unprotected in outer space are wildly different. In one movie, a guy radios for someone who's been ejected into space to breath all the air ...
4
votes
1answer
139 views

What is 'independent assortment'?

What is the definition of 'independent assortment'. I tried researching this term but came back with two results: alleles assort themselves independently of different alleles the alignment of ...
4
votes
0answers
43 views

Why does a pacemaker have a negative pulse? [closed]

Why is the first phase of the pulse from a pacemaker cathodic?
6
votes
2answers
7k views

How hot can a beverage get without burning the tongue?

What is the maximum temperature that a beverage can be without burning the tongue? I suspect there's a maximum temperature that the surface tissue of a tongue can withstand without being damaged (...
20
votes
1answer
4k views

Why do we have five fingers?

Humans (and other humanoid mammals) have five fingers in each hand. Curious to know, why five? Wouldn't more fingers be more useful? Is there any evidence that it used to be different and natural ...
0
votes
1answer
66 views

Clarification on BMI formula

In the BMI formula= (Weight) X 703) / (Height^2) , what does 703 represent? What is a reliable source that I can cite for this answer? weight= lbs height= inches
1
vote
1answer
48 views

Does vitamin D form crystals in the blood with calcium and magnesium?

I read on a vitamin-D product (2000NE) that I should not use calcium and magnesium with it, because it can result crystal formation in the blood. I googled, but find anything about this. Is it true? (...
3
votes
2answers
268 views

How does the cell regulate different metabolic pathways?

I heard somewhere that cells use different nucleosides bound to triphosphates e.g. ATP, GTP, CTP and other modified compounds: NADH, NADPH to distinguish between different metabolic pathways and so ...
2
votes
2answers
118 views

Does the cellular response to every receptor work the same way?

I heard somewhere that activating any receptor results in the same intracellular response (signaling) which involves NF-κB. If that is true, I hardly understand how the cells distinguish between ...
4
votes
1answer
58 views

How to evolutionary explain menstrural cycles synchronization? [closed]

Sorry, I can not indicate the source, but I read that menstrual cycles of women who live in the same house over time sync. Is it true? How does it work?
2
votes
1answer
50 views

Relieving pain by massage

How come the pain in our body, primarily due to excessive physical exercises, vanishes after having a massage? What is the mechanism?
6
votes
1answer
46 views

Would constant light or fading light be registered as more wakefulness promoting by the Supra Chiasmatic Nucleus?

During the fall and winter season, a number of people are experiencing Seasonal Affective Disorder. One of the way it has traditionally been treated is with a dedicated lightbox - a very high ...