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183 Answered Questions for the topic human biology

Human Biology Biology Neuroscience


Why do the two hemispheres of the brain control the opposite sides of the body?

Why does the left hemisphere control the right and the right hemisphere control the left? I googled it but didn't find a good answer regarding this. Could someone explain? Does this adaptation help... more
Human Biology Biology Cell Biology


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

How many human cells are there in our body, on average? Wikipedia ( says 10<sup>13</sup>:> Bacterial cells are much smaller than human... more
Human Biology Biology Cell Biology


A hypothetical nerve damage question?

If a 100 pound bucket is dropped on someone's hand, what will this do to the nerves, will they get crushed, will they die? And how will this affect that person's ability to feel or move their hand?
Human Biology Biology Neuroscience


What do you see when your eyes are closed?

If you are in pitch black and you close your eyes, you sometimes can see strange shapes of various colors. A lot of the time these shapes and colors change as you observe them. This phenomenon... more
Human Biology Biochemistry Nutrition


Why can't you just take a vitamin? Why you need a healthy diet on top of that?

From what I understand, your body needs certain amounts of vitamins and minerals to maintain health. Why can't we just take enough pills to obtain these vitamins and minerals?
Human Biology Biology Infection


Why was disease transfer to the Americas one-way?

It is well known that the European colonists brought many infectious diseases to the Americas, and that these had a deadly effect on the native populations, because they had no immunity to them.... more
Human Biology Biochemistry Inflammation


Why doesn't surgical steel cause inflammation?

It seems some very specific alloys like implant surgical steel and titanium don't cause inflammation in the human body, but when I asked my doctor about it, they simply said "it just has some... more
Human Biology Biology Death


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... more
Human Biology Biology Sleep


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... more
Human Biology Biology Senses


Why does mint oil feel cold on the skin?

When putting (japanese) mintoil on the skin it produces a cool feeling. You can experience this, when adding it to your bath or using a spray with mint oil on your skin. The cool feeling occures... more
Human Biology Biochemistry Lipids


What do sphingolipids do in humans?

I want to know the significance of sphingolipids in human. I have learnt that sphingomyelin is the most significant type of sphingolipid in human. Also that the sphingomyelin serves as a structural... more
Human Biology Biology


What is the armpit hair for?

Modern human beings, especially women, cut their armpit hair. It seems to me the armpit hair is trivial/useless. Shortly speaking, what is the armpit hair for?
Human Biology Biology Eyes


Superhuman eyesight?

My ten year old son was reading car number plates that were too fast, too far away and at the wrong angle for any of us to read or even believe that it was possible for him to read. We thought he... more
Human Biology Biology Cell Biology


What kinds of cells does human saliva contain?

I have heard that our saliva contains cells. What cell types can be found in human saliva?
Human Biology Biology Evolution


Height and natural selection in humans?

I watched the documentary "Evolve" recently and in the segment on "size" Scott V. Edwards, Harvard evolutionary biologist mentioned the idea that humans might evolve to be 7' tall in 'hundreds of... more
Human Biology Biology Neuroscience


Is it correct that the body only responds to the most painful stimulus?

*I'm rather ashamed to say that this question is partly based on an episode of House.*I have previously heard that, if there are multiple simultaneous painful stimuli, the mind will only feel the... more
Human Biology Biology Medicine


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... more
Human Biology Biology Vitamins


Why do Humans not produce Vitamin C like other mammals?

Why do most mammals produce their own Vitamin C? Why do Humans not?
Human Biology Biology Cell Membrane


Can general soap kill bacteria?

I have read that general soap can kill bacteria by opening holes in the bacterial membrane., I found some articles as well saying that it... more
Human Biology Biology Human Anatomy


Will humans and animals be harmed by frequencies outside their hearing range? ?

The human ear (for example) is sensitive to frequencies from 20Hz to 20kHz. Any sound beyond that limit would not be heard by us naturally. 1. Will it harm us (effect our ability to hear) when we... more
Human Biology Biology Brain


Supercomputer Vs Human Brain?

With supercomputers doing calculation in petaflops ($10^{15}$ Calculations per Second), have we crossed the speed of Human Brain?
Human Biology Biology Evolution


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... more
Human Biology Biology Ant


What do ants do with human finger nails?

There is place in my house where I cut my nails. Here, there is an ant hole where an ant colony is seen.Whenever I cut my nails from here, they take my nails inside their hole. I was wondering what... more
Human Biology Biology Immunology


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... more
Human Biology Biochemistry Human Anatomy


Why does the ring finger not move independently?

Why is it that we need to move little finger in order to move ring finger with it? For example, put your palm on a table and fold your middle finger inside. You won't be able to move your ring... more

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