Biology pertaining to humans.

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Can a person really die quickly from biting their tongue?

A common trope in certain circles (like Eastern martial fiction), is someone committing quick suicide by biting his or her tongue. But is this really possible? The internet turns up millions of ...
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93 views

Functionality of vitamin A, Bx, C, D, E, K as used in cosmetics for the skin?

I was wondering if someone can compare the functionality of vitamin A, Bx (x means numbers, such as 1, 2, 3, ...), C, D, E, K in the skin? They are used in cosmetics but what is their actual effect? ...
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156 views

How do the pharmacodynamics of the NSAIDs differ and are there “resistant” COX phenotypes?

I know that the non-steroidal anti-inflammatory drugs (e.g., aspirin, ibuprofen, naproxen) affect the enzymes cyclooxygenase (types I and II). Is there any difference in the degree to which these ...
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What is the main challenge in creating a chemical male contraceptive?

More than 50 years after hormonal contraception for women was invented, a contraceptive pill for males is still not available. With the obvious major biological differences in mind, why does it appear ...
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37 views

Enlargement of thyroid gland

Why does thyroid gland enlarge both in hypothyroidism and hyperthyroidism? Hypothyroid goitre is due to lack of iodine in diet and hyperthyroid goitre (Exopthalmic goitre, Grave's disease) is due to ...
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50 views

Counterintuitive action of Vitamin D?

Vitamin D acts in a way which to me is counterintuitive. It functionally supplemets Parathormone. It in the intestinal tract steps up calcium absorption by altering nuclear gene expression and also ...
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39 views

Database of Medical Assertions

Can anyone point me toward a computationally-accessible database of medical assertions? I'm looking for something where each row in the database contains a single unit of knowledge. It could either be ...
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178 views

Why do people sleep with their eyes open?

It's a fact that some people sleep with their eyes open, but why does that happen? Is it normal behavior, not a symptom of any sort of disorder? Are there any (dis)advantages to sleeping with eyes ...
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91 views

Can someone explain the color-changing unit (CCU) to me?

I've been physically carrying out serial tenfold dilutions on samples of Ureaplasma to work out the color-changing units (CCU). As a definition, the CCU is the highest dilution at which there is a ...
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148 views

What is the effect of garlic on intestinal flora?

Now that we can compare whole microbiomes, has there been investigations on the effect of garlic (or diallyl disulfide, its main ingredient) on intestinal flora? From the proven antimicrobial ...
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72 views

What controls the feeling of discomfort/comfort before and after sleep?

I'm interested in which biological systems or hormones are involved in the following phenomenon: Before sleep it may be difficult to find a comfortable position, and muscular aches and pains are more ...
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57 views

Do Asian women have more difficult births than Europeans?

I recently heard a claim that Asians in general have more difficult births than Europeans. Is this true? I have found a few studies(1,2) on the effect of ethnicity on birth outcomes but they seem to ...
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38 views

How many blood types are there?

In total how many blood types are there? And why do people normally know only 8 of them? (A+, B+ , AB+ and O+ and Rh- counterparts)
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78 views

Can humans transdermally absorb minerals from ocean water, and if so how much?

According to several studies quoted here, chemicals can be absorbed by the skin transdermally, at least under certain conditions. When it comes to elements in seawater like sodium, magnesium, ...
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59 views

How is color information transmitted from eye to brain?

Is it frequency-modualated or are different colors transmitted by different axons? I know that each ganglion cell is connected to multiple photoreceptors. How does it tell the brain which ...
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40 views

How well do we notice asynchronicity?

I'm stopped at a stoplight and, with nothing to do, my thoughts wander to the timed don't-walk sign that governs any pedestrians who might wish to cross the street I'm driving along. I can see two ...
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42 views

Do all humans experience flatus regardless of their diet?

Flatus frequency is affected by diet, so I was wondering if flatus production solely depends on the food eaten, meaning that some people never ever release flatus because they don't eat any ...
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49 views

Why do some women have menstruation-like spotting throughout their pregnancy?

An interesting question that was asked during a lecture about human reproduction: what is the biological mechanism behind some pregnant women getting monthly spotting that they mistake for a regular ...
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187 views

What are the advantages and disadvantages of being ambidextrous?

What are the advantages and disadvantages of being ambidextrous? We have two hands and we nearly can't use one and this seems like a weakness, and a stupid one when you first think about it. But ...
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Why do fresh cavities form from the margins of sliver amalgam fillings on teeth?

Silver amalgam fillings predominantly contain silver a known bactericidal agent and mercury which a known toxin and has bactericidal property. So how is it that the plaque bacteria survive near the ...
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83 views

What tests can be performed to test the purity and quality of the raw peptide HCG (Human Chorionic Gonadotropin)

What tests could be run to test the purity and type of HCG? We are looking to purchase HCG from China but the purity and quality varies between labs, we are able to receive samples of the raw peptide ...
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22 views

What is an explanation of the dual role of calcium hydroxide in teeth?

Calcium hydroxide induces dentine formation in permanent teeth, while it causes resorption of tooth in deciduous teeth. How is this dual role explained?
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Movement of stem cells from mother to fetus

Recent results from J Lee Nelson and colleagues (Sci Am. 2008 Feb;298(2):64-71; available as full text through Google) show that cells from the mother were found in a person aged 46. Logically, these ...
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How to use mechanical microstrainer to extract tissue proteins from human?

Background: There are many methods to extract proteins form human tissues out there. The majority of them use an extraction buffer containing variable concentrations of detergents and protease ...
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How do omega-3 fatty acids reduce cholesterol at the molecular level?

I have heard that omega-3 fatty acids found in fish are a good way to prevent/reduce cholesterol problems. My question is how do omega-3 fatty acids do that: what are they doing on a chemical level ...
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HSL Lightness vs Eye sensitivity

In a monochromatic spectrum, is the human eye equally able to distinguish between lighter colors just as it is in distinguishing between darker colors? I mean is there really a linear relationship ...
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What are the physiological effects of wine?

I have read that alcohol in general and wine in particular can have advantageous as well as detrimental effects on human health. Is this true? What are the physiological effects of consuming wine in ...
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Is there an entry-level circadian model of serotonin, ghrelin, dopamine and the sense of well being?

I've long been interested in circadian rhythms and recently came across a variety of articles that appear to indicate that the following neurotransmitters, transferases and hormones are connected. ...
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54 views

Can frequent ultrasound diagnostics be harmful?

Are there any short or long term effects apparent in tissues if a zone (or the whole) of human body is scanned with ultrasonic waves often?
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47 views

Do humans have chemosensors for nutrients or chemicals?

I'm reading about chemoreceptors on Wikipedia, and see that the typical ones are mentioned: taste, smell, co2. I would like to learn more about the other kinds of chemoreceptors that humans may ...
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115 views

Virucides - Herbal and otherwise, for HHV6 type virus or any inner-cell virus

Does anyone know where I can find a reliable list of virucides (not anti-virus) that can be used by humans? This virucide must be able to affect viruses that are already inside the cells. St John's ...
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How to seek information on the duration of biological entrainment processes in mammals?

This is a question that is a little bit hard to define for me. I'm interested in learning more about times of "attractor/entrainment" processes that may take place in the body/brain of mammals, and ...
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208 views

Can the sleep/wake cycle be influenced by non-visible spectrum electro-magnetic radiation?

I've been reading a few papers on Melanopsin and Suprachiasmatic Nucleus (SCN), and see that the sleep/wake transition is ...
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59 views

Are there any situations in which phenylephrine is preferred to pseudoephedrine?

In the mid 2000s in the US, due to issues of drug enforcement, pseudoephedrine containing medications were brought behind the pharmacy counter and in most cases require ID, and phenylephrine was ...
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190 views

What is the timing of information assimilation within a human brain?

A little background: I'm an avid dreamer and have great dream recall, sometimes up to 5-7 per night. In my experience, I can sometimes trace some elements of the dream to an event that occured ...
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23 views

Nearly Exhaustive List for Cholesterol Pathways

I have run across an interesting case that is similar to only two others I've encountered. What makes it interesting is the combination of undetectable (under normal testing conditions, can elaborate ...
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31 views

How can one accurately diagnose human hearing loss without surgery?

In a human, if you were to avoid a tympanotomy, how could you distinguish between a blocked Eustachian Tube, a ruptured eardrum, or Perilymph Fistula? For instance take the situation where a young ...
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Is there a homeostatic setpoint for number of hours of sleep required by a human?

I've heard this TED.com talk about dieting and it mentions that there's a very definitive setpoint within the human brain about how much a human should weight. The speaker mentions that after as much ...
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48 views

Why are people tired after surgery?

I had surgery when woke up I felt like I only had 20% energy & felt extremely tired. Is this a common sensation? Why do people feel so tired after surgery?
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Why does the ovum prefers to be arrested at metaphase 2 of meosis before fertilization? What is the possible advantage of this process?

Why does the human ovum prefers to be arrested at metaphase 2 of meosis before fertilization? What is the possible advantage of this process??Please help me with it.
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Sodium levels and blood pressure

Why does low $\ce{Na+}$ levels cause hypotension (low blood pressure). Alternatively, why does excessive intake of $\ce{Na+}$ cause hypertension or high blood pressure? From what I ...
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Possible long term side effects of IV iodine contrast

There are some illnesses that are linked with Iodine deficiency, most notably Multiple Sclerosis (MS) and Parkinson's. The resulting correlations suggest that mortality from Parkinsonism, ...
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53 views

Are simple esters like those used as flavouring agents metabolised into their constituent carboxylic acids and alcohols in the human body?

By this I mean to ask whether say ethyl butanoate is hydrolysed in humans into ethanol and butyric (butanoic) acid. This is of interest to me as a pharmacology researcher because butyric acid, for ...
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113 views

What naturally produced drug causes 'a tingleing euphoric rush'

What naturally produced drug causes a 'tingleing euphoric rush' through your body, as well as a 'wave of goosebumps'? I've always been interested in this sensation, two of the last times i can ...
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39 views

What parts of the brain are involved in regulating blood pressure in mammals?

I'm reading this Wikipedia article on blood pressure and its regulation, and it mentions that medulla is involved. however, I vaguely remember reading another article on Wikipedia and it mentioned ...
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130 views

Would a spinal injury decrease human height?

A woman I know has been losing height at a rate of 10cm a year following a severe spinal injury. How is this possible? What kind of injury could cause such progressive loss of height? Could this be a ...
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33 views

What processes are responsible for focusing on an image only seen by one of the eyes?

When a person is spying from around a corner with only one eye, it's rather easy to ignore the other eye's image, since it's probably much darker, because one usually spies around a corner standing ...
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151 views

Size order of human organs

Wikipedia states that the liver is the largest internal organ in the human body. How does it relate to the sizes of ex. the lungs and small intestines? I've been having this personal image for years ...
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Why do ion concentrations change with different secretion rates in pancreatic juice?

Why is it that when secretory rate increases in the pancreas the concentration of chloride ions decreases, and the concentration of bicarbonate increases in the production of isotonic NaCl secretion? ...
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How does geography affect morphological features of the human body

I've seen many times how a person born in one place, goes to another country for a long time, and then they start looking more like the people there, but I never found out how it works. This report ...