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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Why will tissue from identical twin be rejected in some cases?

From Medline Plus : Also, transplants from one identical twin to another are almost never rejected. My question : Why can a tissue from an identical twin be rejected ?
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2k views

What causes REM atonia to be lost in sleepwalking?

I understand that in normal REM sleep the voluntary muscles are in effect paralysed in order to prevent an individual acting out their dreams. This paper indicates that there are likley to be ...
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2answers
386 views

How to design an experiment with scent triggered memory recall in humans?

I've recently learned that scents can trigger memory recall in humans, and am thinking about setting up an experiment where I would attempt to induce memory recall through exposure to scents. In ...
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2answers
415 views

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 ...
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1answer
54 views

Any forms of pneumonia that can be caught?

I am aware of the fact that there are several different types of pneumonia. However, I am wondering if any of these types of pneumonia are contagious from person to person. Is this possible?
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2answers
131 views

Which was the last significant event in human evolution? What's next?

At 10.000 BC (12 ka), we became the last of the Homo species on Earth. In evolutionary terms this is a very little time range to something happen, but I'm wondering anyway, in this meantime which are ...
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3answers
213 views

Can children restore brain cells?

By "children" I mean young people at the age of 10 or lower. I know that the adult brain cannot restore brain cells, but what about children? I mean, the brain must develop from a few cells to a 90 ...
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1answer
359 views

Why basement membrane thickens in diabetes mellitus?

Untreated diabetes mellitus may lead to blindness and kidney failure because the basement membrane of small blood vessels in these organs thickens due to increased production of collagen and laminin. ...
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0answers
71 views

Relationship between small and large fast-twitch motor units

When large fast-twitch motor units are temporarily fatigued, non-fatigue small motor units in the same muscle are impaired for small delicate tasks. Why? When impulses from the brain comes down, the ...
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1answer
84 views

Average face shape

I am doing face detection application where every face detected is inside a rectangle. The rectangle always contains some background behind the face and now I need to extract as much of the face as ...
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1answer
585 views

Crusty eyes in the morning

Often, after waking up from a night's sleep hard, flaky, pale yellow crystals are deposited around the eyelids (which easily wash off with water). What are these? Why are they yellow? What are they ...
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0answers
81 views

Width of vein in finger

I am working on my bachelors thesis, where one part of it is to find width of vein in fingertip. I use database images and extract vein patterns from it, but i have to calculate the width of vein and ...
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1answer
33 views

When does exposure to an allergen increase / decrease allergy?

In immunotherapy a person is regularly exposed to an allergen to decrease the allergy. Yet apparently "repeated intranasal challenges ... induces robust allergic airway inflammation, " [0] So when ...
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4answers
566 views

Strictly from a biological perspective, what is the functional expectation of a human being [closed]

Just like the title says: Strictly from a biological perspective, what is the functional expectation of a human being. No religious or philosophy-based answers will be accepted, we are talking ...
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2answers
240 views

Is there any biological reason for humans to rest after x days of work?

A lot of people live in a 7 day cycle, where 5 days of work are followed by 2 days of "rest". Vacations and holidays can increase the time available for resting. Is there any biological reason for ...
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1answer
222 views

List of heritability estimates in humans?

Many people on this site ask questions that directly or indirectly have to do with heritability in human. Do you know a list of estimates of heritability of various traits in humans? Or could you try ...
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1answer
200 views

Task-dependent “reversed” handedness: why use left hand for some tasks? How is it controlled by the brain?

I am right-handed. Which means that when I hammer down a nail, I hold the nail in my left hand, with which I can hold it straight and at a controlled position. This is true in situations where the ...
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1answer
103 views

Where does the fate map of a human embryo end?

I'm confused about the fate map of a human embryo. Is it just a particular part of the embryo development or does it include everything, from the conception (germinal stage) to the day the baby is ...
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3answers
860 views

Does our eyeball increase in size as we grow?

Does the size of the eye increase as we develop from the stage the complete eye first forms to infancy and then to adulthood ?
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1answer
292 views

Will neurons live after the death of a human? If so, how long?

I don't know if this is correct or not, but I have heard this from a friend and I want to get a clear explanation about this.I hope there is some one who can help me.
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1answer
50 views

Why are many anti-malaria drugs gap junction antagonists?

Why are many anti-malaria drugs gap junction antagonists? My professor recently just mentioned that many of the anti-malaria drugs block gap junctions. i am wondering if this blocking is important ...
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4answers
245 views

Why do the humans become sleepy after meals?

I don't know about all the mankind, but I know enough people, who becomes sleepy after their meals. Also, I'm not sure, what kind of food do they consume, but I personally get sleepy almost from any ...
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1answer
279 views

For emphysema, which of the respiratory volumes is effected. I have a couple of educated answers

It could be the tidal volume because it effects how a person inhales and exhales normally. It could be the residual volume and functional residual volume, because it increases its amount. Because it ...
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1answer
377 views

What is the beneficial function of IgE antibody?

Dont tell me the "function" of IgE is to cause allergy ! In whatever texts I have seen it is written that IgE is important to cause allergies but what is the beneficial function of IgE ? Why was it ...
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2answers
183 views

How the lungs clear themselves?

Looking at my computer's fan I can say that a lot of dust is collected on it not less dust should be collected in the lungs, not to mention some inhaled parts of food. How the lungs clear themselves ...
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2answers
311 views

Does Science Say That We Should Die? [duplicate]

Excluding situations where you die from accidents, the main reason for death is -generaly- diseases. And usually it is about an organ which becomes "tired" after many years. These results are all ...
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2answers
183 views

Why did women historically have such a high mortality rate during birth?

Historically women had a relatively high chance of dying while giving birth. At first thought it seems to me that this would be a disadvantage for the species for the obvious reason that a dead ...
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1answer
324 views

Why is membrane potential not zero at equilibrium?

For the squid giant axon, the membrane potential computed by the Goldman equation is -60mV. And the Nernst potentials are (the differences between the K+ and the Na+'s Nernst potential and the ...
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2answers
645 views

Would exposure to a strong magnetic field have deleterious effect on the human?

This article states of a 25T magnet, ".. If are ever caught in one of these devices, let’s just say you probably won’t live to tell the tale." Is the above statement in order? What effect would ...
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1answer
93 views

Do people with gout live longer?

Antioxidants reduce damage to tissue (by scavenging the free radicals) and thus may reduce ageing.It is known that Uric acid is a very good antioxidant. People with gout have excess accumulation of ...
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1answer
64 views

What is this abbreviation CT in female reproductive system [closed]

I have this sentence in my notes Ovary is surrounded by tunica albuginea and the cortex keeps the primordial follicles. The medulla containing CT and blood vessels develop from mesonephros. I ...
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2answers
535 views

How was the Huntington's disease gene's location found?

I read in the book "Why we get sick." by Nesse and Williams that: Steady detective work and fabulous luck have enabled geneticists to pinpoint the Huntington's gene on the short arm of ...
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1answer
2k views

Near point and far point of myopic eye

Suppose a person wears the specs of power -6D, the far point for that person is 16cm. But the near point of normal eye is 25cm. So, is the near point of a person with myopia (having far point less ...
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2answers
181 views

Advantages of pain sensation?

The hazards of congenital insensitivity to pain (CIP) are well-known. This question is about the obverse: what selective advantage, if any, does the normal sensation of pain confer? I'm thinking of ...
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2answers
8k views

Mitosis in human body

I've heard that stomach lining has the fastest reproducing cells and the brain has the slowest. Where in the human body does mitosis occur and at what rates do these cell reproduce? Is there a chart ...
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1answer
400 views

Influence of alcohol on brain cells

As I am not related to biology, I would appreciate if you can keep your answers as simple as possible. My question is about the influence of alcohol on the brain. As far as I know, drinking alcohol ...
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1answer
329 views

Consequence of touching Formaldehyde

I accidently touched formaldehyde some days ago. Skin on my hand got dehydrated as if I had placed it in salt solution. I washed it with water and it returned to normal state after 5 minutes. But now ...
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1answer
272 views

What causes Paresthesia (Pins and Needles) at a cellular level?

I've looked it up in plenty of places like the Wikipedia page and such, and it is clear that the most common cause of Paresthesia is either a fair amount of pressure on a specific patch of skin ...
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2answers
161 views

Is solving cancer required in order to avoid aging?

When the telomerase enzyme is not active the telomere shortens every time the cell duplicates leading to a reproductive limit (Hayflicks limit). On one hand this is a believed reason for aging. On the ...
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1answer
3k views

Do we actually get more sick (flu/cold) during winter?

The word flu derives from the Italian phrase "influenza de freddo" meaning "influence of the cold". Indeed it is that time of the year when my colleagues seem to have the flu/cold more often than ...
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1answer
47 views

Functioning of BCG vaccine

I read (from Nature Volume507, S4–S7 (06 March 2014) : For reasons that are poorly understood, BCG protects only infants; it is ineffective in older children and adults. Its efficacy also ...
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1answer
26 views

Association of shorter telomeres with heart disease

From this paper Those with shorter telomeres in blood DNA had poorer survival, attributable in part to a 3.18-fold higher mortality rate from heart disease (95% CI 1(.)36-7.45, p=0.0079), and ...
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2answers
320 views

What is the eye muscle status when you stare at distant view through a glass wall?

The book said when you look at object close to you, the eye muscles contract and vice versa. I wonder what will be the status of the eye muscles when I stare at distance view (such as a mountain) ...
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1answer
89 views

How many different smells can a human recognize?

How many different smells can a human recognize? If the space of smells is not discrete, how many dimensions it has (for example, the space of colors is three-dimensional).
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1answer
147 views

Evolution of Homo Erectus to Homo Sapiens

I just read an article on Wikipedia and noticed that some similarities between Homo Erectus and Homo Sapiens in the "Comparative table of Homo species". My question is; Is it possible to say that ...
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1answer
64 views

Is it easier to burn a calorie of fat or a calorie of a carbohydrate?

Say someone eats 100 calories of chocolate vs. 100 calories of carrots. Something tells me that eating the chocolate will lead to you generating more fat. Will it? Is it harder to burn the calories ...
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2answers
319 views

How does a veggie-less diet affect the human body?

I have some question, which I'm sure would fit better in the fitness section but proper answers should probably come from someone that knows biology. My question is rather simple. How can a person ...
3
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1answer
374 views

From a purely biological perspective, how does an optimal human diet look? [closed]

There is hardly any subject as contested in the media as what humans should eat. Usually, such discussions are devoid of actual scientific reasoning, though they all claim to be backed by scientific ...
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1answer
219 views

Raising two legs together while lying on bed

Let's do some exercise(duh!) Ok so lie on the bed. Lift your left leg. Put it down. Lift your right leg.Put it down. Easy? Now lift your left leg and without putting it down, lift your right leg. ...
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1answer
224 views

Why don't we have more cone cells (bigger fovea)?

Background Apart from being able to sense color, cone cells are able to perceive finer detail and more rapid changes in images, because their response times to stimuli are faster than those of rods. ...