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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3
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1answer
443 views

Do adipose cells divide in adults?

I have a dim recollection of having heard that when humans gain weight, adipose cells just get larger, rather than dividing. True?
6
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1answer
7k views

Will a bone marrow transplant change one's blood type?

Will a bone marrow transplant change one's blood type? Or is the donor blood type matched with the person before transplant?
2
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3answers
528 views

Is there such thing as “half-life” of dopamine?

If a dopamine is released at T=0 and binds to receptor D2, what determines the time when the concentration of this neurotransmitter bound to the receptor reaches half of the original concentration? In ...
9
votes
2answers
327 views

How is human biological clock modelled in modern science?

Im an engineer by education and i program a lot, so the question sounds weird to people from other disciplines. Im trying to better understand the human biological clock. Yet i do not really know ...
4
votes
1answer
349 views

Do effects of caffeine on human body change with habitual use?

I've been reading about homeostatic nature of a lot of neurobiological processes - the brain is trying to maintain a balance by desensitizing receptors, re-uptaking and breaking down ...
4
votes
2answers
698 views

Does the brain and the body use the same energy source (glucose/ATP)?

I've heard that the brain consumes quite a lot of oxygen and energy, compared to the rest of the body. What I'm interested in is if this is the kind of energy and oxygen that the rest of the body ...
2
votes
0answers
179 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 ...
2
votes
1answer
52 views

PGC-1β Sod2 limiters/blockers

I'd like to block a percentage of PGC-1β or Sod2 expression. According to the following paper's figure beta-blockers inhibit some expression of PGC-1α. Are there any medicines/chemicals which safely ...
2
votes
2answers
120 views

Is there some branch of biology that deals with the entire organism?

I'm reading about various parts of the human body and brain and started to wander if there's a branch of biology that deals with the entire human? I know that there are branches various -biologies, ...
10
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1answer
182 views

Does stress physically age our body?

Going by the assumption that stress eventually triggers a flight/fight response, and the subsequent realization that flight/fight puts the body in a system of readiness to use it's available resources ...
3
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2answers
144 views

What is the biological basis for a human's ability to think clearly and be aware while “fighting/competing”?

I'm interested in learning more about the biological systems or hormones or parts of the brain that affect short term (<15 minutes) ability to concentrate attention on the task and be aware of the ...
4
votes
1answer
262 views

What is the molecular basis of hangovers?

Well, most of us have experienced the wonderful feeling of the dreaded hangover. How does it work exactly? I imagine it has something to do with dehydration but what are the underlying mechanisms? ...
1
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0answers
59 views

Does Dorsal Raphe Nuclei firing pattern change in response to voluntary breathing?

I'm reading this paper, which discusses how Serotonin may be involved in motor functions of mammals: 5-HT and motor control: a hypothesis . The paper includes the following diagram of the Dorsal ...
4
votes
2answers
61 views

Is there a circadian component to hunger?

I'm wondering what produces the feeling of hunger in humans. Checking Wikipedia revealed that leptin and ghrelin are two hormones involved. I've also read that the digestive system produces its own ...
21
votes
5answers
405 views

Are there any substance that are more dangerous at low dose than at higher dose?

It is commonly admitted that The dose makes the poison which means as a person, the more I take a substance, the more risk I take for my health. There is even an indicator called LD50 (see ...
3
votes
1answer
2k views

Slow-oxidative fibres vs fast-glycotic fibres

Why do slow oxidative muscle fibres contain more mitochondria compared to fast-glycolytic muscle fibres?
4
votes
1answer
247 views

How quickly can the human heart rate rise and fall?

How quickly can the human heart rate rise and lower? For example lets say a human heart rate is rested and is at 60BPM and that person is suddenly scared to trigger their fight or flight reaction. ...
9
votes
1answer
1k views

What determines testosterone exposure in womb, baby's genetics or mom's body?

I read this article which has the following quote: The ratio between index and ring finger is believed to be linked to exposure to the male hormone testosterone in the womb. And I wonder what ...
8
votes
1answer
526 views

What conditions are necessary for HPL (human pancreatic lipase) to activate?

What conditions are necessary for human pancreatic lipase to activate? Is there an optimal temperature or pH? How quickly does it take effect?
2
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0answers
21 views

How to seek information on the duration of biological entrainment processes in mammals? [closed]

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 ...
-1
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1answer
5k views

Ramifications and possibility of a diet consuming exclusively of human semen

Semen is a thick, nutritious liquid, rich in vitamins (such as C, B12), amino acids, lipids, monosaccharides (fructose), et cetera. Can semen's ability to fulfill the needs of human organism provide ...
3
votes
1answer
112 views

Where are -HCl supplements absorbed in the human digestive system?

I see that quite a lot of drugs and dietary supplements sold in the USA have -HCl(hydrochloride) added to their name. For example pyridoxine hydrochloride for Vitamin B6. I'm interested in knowing ...
0
votes
1answer
266 views

Why is offspring of identical twins not identical?

When identical twins marry identical twins, the children of the couples will be full genetic siblings but why are they not genetically identical?
9
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3answers
125 views

Adipocyte Density

People who are overweight and wish to lose weight, often do so because they are concerned about looking too big. Their increased size is attributed to an increased volume of fat. When people try to ...
8
votes
1answer
89 views

Which aspects of renal physiology are standing in the way of an artificial (mechanical) kidney?

Scientists have been able to create artificial organs with varying degrees of success. The mechanical heart (in its various forms, e.g. ventricular assist) is able to sustain life for some period of ...
8
votes
1answer
196 views

Does the oxygen concentration equilibrate between red blood cells in the liver sinusoids?

In the sinusoids of the liver, venous blood from the hepatic portal system mixes with arterial blood from the hepatic arteries. Do oxygen molecules move between oxygenated RBCs and non-oxygenated ...
9
votes
1answer
190 views

What are the clotting factors' effect on avascular necrosis development?

Do clotting factors tpa and pai-1 lead to degenerative osteoarthritis in the same way that lupus anticoagulant and prothrombin might? Is one of these pathways particularly detrimental during formation ...
18
votes
2answers
334 views

Can an adult without genetic lactase persistence still develop a tolerance for dairy foods?

While investigating the rise of adult lactose tolerance, I came across the news that China has been encouraging its citizens to drink more milk, even though most of the Asian population lacks the SNP ...
4
votes
1answer
5k views

Does mixing alcoholic drinks really make you more drunk?

There is plenty of anecdotal evidence ("beer after wine and you'll feel fine, wine after beer will make you feel queer") that mixing alcoholic drink types leads to a stronger effect, but I can't find ...
3
votes
1answer
166 views

Can a person die instantaneously from internal damage to the brain?

Given the human heart is autonomous, can a person die instantly from internal damage to the head/brain? I would expect the heart to continue to pulse until it ran out of energy ... My contention is ...
8
votes
2answers
349 views

Where do the bacteria within the vagina originate from?

I understand that it's feasible the bacteria within the gastrointestinal tract originate from the food we eat and air we breath, but where does this population of microbes originate from?
1
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0answers
43 views

Can we make any judgements about sleep or readiness to sleep from a heart rate metric and/or pulse oxymetry?

I'm looking at inexpensive and un-intrusive ways to quantify the state of human body/mind . One of these is Actigraphy, which is a study of human motion over time. This can be done with an iPhone ...
2
votes
0answers
308 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 ...
4
votes
1answer
311 views

In the vacuum of space would death be instantaneous?

I was arguing with my colleague about this matter (I'm not going to mention which side I fall on). Would death be immediate in the vacuum of space? For example, if I was suddenly teleported into the ...
3
votes
1answer
311 views

How are melatonin levels measured in humans?

I'm wondering how it is possible to measure diurnal variations of melatonin levels in humans. I keep reading that there should be a large difference in amplitude between melatonin levels measured at ...
4
votes
1answer
52 views

Are there yearly variations in HIOMT (HydroxyIndole-O-MethylTransferase) availability?

I'm reading a booklet on melatonin published in 1996, titled "Melatonin and the Biological Clock". And see the following statement: HIOMT (HydroxyIndole-O-MethylTransferase), one of enzymes of ...
4
votes
1answer
594 views

Is there a relationship between Melatonin, Norepinephrine and depression in humans?

I'm reading a booklet on melatonin published in 1996, titled "Melatonin and the Biological Clock". This particular paragraph caught my attention and I would like to better understand what it means: ...
12
votes
2answers
447 views

Could an “overactive” brain increase the chances of Alzheimer's Disease?

From Raichle ME. 2010. Two views of brain function. Trends in cognitive sciences 14: 180–90: Alzheimer’s disease (AD) is the most common cause of progressive cognitive decline and dementia in ...
16
votes
2answers
378 views

Why would diffusion be faster across a non-specialised tissue?

The standard protocol for a person experiencing chest pains is to chew a 300mg aspirin tablet, the argument being that chewing rather than swallowing the tablet results in the aspirin entering the ...
4
votes
2answers
132 views

Does age affect the frequency of flatus?

Is there any relation between age and the frequency of flatus? I often have this feeling that older people f*** more often than younger ones. Is this feeling scientifically correct?
3
votes
1answer
193 views

What is the relationship between Homocysteine and Norepinephrine metabolic cycles?

I've been researching neuromodulators and have taken a look at the Norepinephrine/Noradrenaline system. The diagram of biosynthesis of Norepinephrine is presented in the wikipedia article: ...
12
votes
2answers
201 views

Can a color-deficient person be made to visualize the missing colors?

Hope this is within the scope of this site. Color-deficient persons lack the cells in their retina needed for differentiating some (or all) colors. However, the part of the brain that actually ...
0
votes
1answer
230 views

From which ancestor species did humans inherit orgasm?

From what ancestors did humans inherit orgasm? Do fish experience orgasm? Are the male and female orgasm the homologues that can be traced to the time when there was no difference in sex between ...
7
votes
2answers
155 views

How was the guided daily amount (GDA) calculated?

We are constantly shown nutritional information on food packaging stating this food contains "x" amount of your guided daily amount. A linked to the values is here. How were these values calculated? ...
11
votes
3answers
1k views

What happens to dextrorotatory amino acids in humans?

As indicated by this question, most of the amino acids in the human body have the L-chirality. As enzymes also have handedness, what happens to the D-amino acids that end up within the human body? Are ...
9
votes
2answers
348 views

Do twins “run in the family”?

My wife and I recently found out that we are going to have twins and so nearly everyone asks if we have a family history of twins. Now I know that the answer for me is that it doesn't matter—as ...
4
votes
1answer
1k views

What does vitamin B6 and B12 absorption depend upon?

I'm looking at my question about homocysteine metabolism and am doing a followup inquiry into vitamins B6(Pyroxidine) and B12(Cyanocobalamin). I've found this interesting bit about vitamin B12 and am ...
1
vote
1answer
58 views

What is the role of Homocysteine in cognitive function?

I'm looking at this link : Homocysteine and cognitive impairments and am looking for more information on specific cognitive impairments associated with elevated levels Homocysteine. That article is ...
7
votes
3answers
246 views

What alternatives are there to the amyloid hypothesis?

Given the recent failure of the Bapi clinical trial, there is a lot of questions that have arised from he amyloid hypothesis. However, I can't really think of many other mechanisms that don't involved ...
4
votes
1answer
87 views

Is there an advantage to having cellulite

There are many ads nowadays advertising cellulite removal, and it causes me to wonder if there is an advantage to having cellulite or if it is just a result of too much fat unevenly spread? Is it ...