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Questions tagged [human-biology]

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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Hematuria due to Nitric Oxide

Drug interactions between properly dosed NO and other medications are not expected, but side effects may include noisy breathing, hematuria, or possibly atelectasis. (pg.no:577; Goodman and Gilman ...
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Most sensitive hearing human ever measured?

The Fletcher Munsen curve shows the lowest spl that humana can hear is -6db around 4 KHz.I assume this curve is average obtained from measuring many people. My question is,what is the most extreme ...
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How hypoxia causes increase in intracellular $Ca^{2+}$?

Ischemia can cause depletion of ATP inside cell which can affect the efflux of $Ca^{2+}$ via energy dependent calcium pumps. This may (How?) cause increase in $Ca^{2+}$ ions intracellularly (Effect of ...
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Why do humans lose subcutaneous fat from the extremities with age?

Why does fat tissue die and shrink on the hands, knees, and lower legs of most people as they age, even when they are overweight? In most people, their bone definition becomes much more visible around ...
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Can you eat cancer cells without risk?

Afaik GMO products are not a real risk to health of course if they do not contain toxins. But how about cancer cells? Like say rhabdomyosarcoma which is more or less a muscle cancer found also in ...
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About how long does it take for a person's eyes to turn black after death?

I have found information about why and how a person's eyes turn black after death, but I haven't found anything mentioning a rough time frame. About how long does it take for a person's eyes to turn ...
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157 views

Why do humans lose subcutaneous fat tissue with age?

Why exactly do humans lose subcutaneous fat tissue with age? It appears that we either lose fat cell volume or we might actually be losing the number of fat cells with age. One hypothesis is that as ...
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Very frequent multiple births in humans

18th century Feodor Vassilyev is said to have had children by two wives, each of whom only ever had twins, triplets or quadruplets. His first wife has 16 sets of twins, 7 of triplets and 4 of quads; ...
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Humans have Cannabinoid receptors. Does that mean we're meant to consume cannabis?

I know the answer is no. But what then explains the name of these receptors being specific to Cannabinoid found in cannabis? Aren't Cannabinoid receptors exclusive to Cannabinoid? Why are they named ...
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78 views

İrreversible dopamine antagonist vs. Dopamine agonist

Can a dopamine agonist reverse the effects of an irreversible dopamine antagonist?
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55 views

What is the chance a given gene will end up in a given gamete?

Let us say a somatic cell had a desired gene. This somatic cell was replicated during interphase so that it had two of the desired gene. It then underwent meiosis. My question then is, what is the ...
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why do we tighten out muscles against cold?

When I'm in shower and I want to open the cold water on myself suddenly I make my muscles so tight before I open the water and that helps so much in being able to handle the shock. Why does tightening ...
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103 views

Is that true that plant stem cells can be used in humans?

I was reading an article (which seems very fake to me) on sensitive topics, but there was one astonishing statement: Stem cells are obtained from certain plants that grow all over the world. Once ...
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66 views

Animals as organ donors and organ's life expectancy

Recent attempts to find reliable organ donors was using genetically-engineered (GE) pigs as heart donors. The pig's DNA is altered so that its tissues will appear identical to the patient's tissue and ...
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1answer
288 views

Is there a correlation between B12 deficiency and cardiovascular disease?

I've read in several health sites that state that high blood homocysteine, as well as low B12 intake, is not only correlated, but actually causes cardiovascular diseases. In order to verify those ...
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Are we evolving as fast as the oxygen is depleting?

How much oxygen saturation have we lost in the last 100 years? As oxygen levels dwindle and industry, deforestation, and population increases, at what year and saturation will the low levels of ...
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Are mosquitoes actually louder than similar flying insects, or have we evolved to hear them?

I've come across many flying insects smaller than the common housefly, but (anecdotally) the only such species that I can hear from an appreciable distance away is the mosquito, with its distinctive ...
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1answer
41 views

Why should collected blood from patients be analyzed as soon as possible?

I'm looking for the possible factors influencing blood samples. What happens to the blood cells esp. WBCs/PBMCs after 8 hours of blood draw? For example, I know that granulocytes may cause oxidative ...
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What is the occipital bun, precisely (in Neanderthals and Homo Sapiens)?

I've read that the occipital bun is an anatomical feature of the Neanderthals, and only because modern humans (except sub-Saharan Africans) carry a few percent of Neanderthal DNA due to ...
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1answer
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Viral susceptiility of Nose and eyes

I read that opening in our face like nose and eyes are one which get us infected with numerous communicable diseases like cold , flu ebola etc. Both these organs have preventive mechanism like nose ...
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Are red blood cells prokaryotic?

After searching "do antibiotics impact the immune system" I found out that antibiotics target prokaryotic cells. It all made a lot of sense thinking about all those yogurt recommendations you get ...
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Is marriage with half-cousin's daughter more risky than marriage with others?

I want to know is marriage with half-cousin's girl more risky than marriage with a non-family girl? Also I like to know if her parent are cousins(but from mother side), does it add more risk to this ...
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What would the RBCs of someone heterozygous for sickle cell anemia look like?

Would half of the RBCs look normal, and the other half sickled? Or would all of the RBCs have slight deformation/sickling? Thanks!
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Why there is no vaccine against Human Immunodeficiency Virus (HIV)?

I was informed by my teacher that this retrovirus changes its RNA, so there is not a drug which can recognize the RNA and somehow inactivates it. Are there any other reasons explaining why there isn't ...
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What if the luminosity of Sunlight increased by 10% [closed]

If the luminosity of sunlight increased by 10%, would people be able to survive outside? Would such brightness of light be very harmful to them, for exemple as much as the Mercury Vapour Lamp deprived ...
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159 views

Why are only few cigarette smokers prone to cancer?

It's tacit that only a few populace of smokers get cancer. What spares the others from it or what specifically cause cancer in those populace? See this Washington Post Article
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Why do people have characteristic body odour?

I am informed that odour (specifically coming from armpits) is due to bacteria residing on the skin do the work of manufacturing the malodorous compounds. So why do people have characteristic body ...
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2answers
99 views

How does 2,3 biphosphoglycerate works to release oxygen bound to the hemoglobin?

I read on Wikipedia that 2,3 BPG binds with the deoxygenated state of hemoglobin and helps in stabilizing it. It was also written that it helps release remaining oxygen from the hemoglobin. How? ...
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1answer
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Frequent urination caused by sound of running water [closed]

I urinate at sound of running water when I brush my teeth or wash my hands . This only happens when I am home
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61 views

Why ketoacidosis is less common in patients of Noninsulin Dependent Diabetes Mellitus?

The other day my teacher said ketone bodies are mostly formed when insulin is less and NIDDM type diabetes mellitus has less chances to grow ketosis. https://medlineplus.gov/ency/article/000320.htm P. ...
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1answer
43 views

Why do alpha-gal allergies only occur after a tick bite if alpha-gal is already present in red meat?

I just read an NPR article about allergies to red meat being caused by tick bites. That stood out to me because I thought allergies are triggered by an initial exposure to some allergen. In this case, ...
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1answer
38 views

Neuroscience - A neuron with two types of synapses (electrical and chemical) at the same time

I learn that the nerves from the Peripheral Nervous System can carry signals from and to other organs of the body. I'm wondering if A Single Nerve carries 1) Only chemical signals 2) Only physical ...
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A human lifespan [duplicate]

Recently, I read an article that said a human lifespan does not have any limit and when a man turns 105 he has a 50/50 chance to survive another year. Some scientists say that a man who will reach the ...
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Is there a specific suffix for “within a cell”? i.e. in a similar manner to how -aemia refers to within the blood

Words like hyperglycemia and hyponatremia refer to the relative level of each component in the blood, not in the cell. Is there a suffix for within the cell? For reference I would like one word as an ...
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37 views

How does LDL leave the circulatory system and enter the interstitial fluid to deliver cholesterol to cells?

I have read that small molecules like oxygen and carbon dioxide diffuse through the capillaries, but larger structures can't fit through. This answer indicates that some proteins go through via ...
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98 views

Why is the hippocampus considered to be a cortical structure but not the amygdala?

I'm having some trouble understanding the anatomical differences that classify the hippocampus as a cortical structure but not the amygdala. I have included the screenshot of a diagram from Gray's ...
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What does it mean that growth plates are morphologically not equal but histologically are so?

I'm reading a text, and here it is written that epiphyseal plates / growth plates are morphologically not equal but histologically? Shouldn't it be the other way around?
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275 views

Mechanism by which hypokalemia reduces insulin secretion

Is there any known mechanism by which hypokalemia reduces insulin secretion? This video explains a mechanism, but its inherently wrong because ATP dependent K+ channels will allow movement of K+ from ...
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1answer
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Why is exercise good? [closed]

The fact that exercise is healthy is a bit counter intuitive to me. If we have any machine, a car for example, the less we use it the longer it lasts. Then how is it that using our body to do sports, ...
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46 views

Can toilet or sewage aerosol transfer eggs of human parasites?

Flushing a toilet produces hundreds of thousands of tiny droplets containing viruses and bacteria (source): Up to 145,000 droplets were produced per flush, with the high-energy flushometer ...
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379 views

Spermatogenesis question

I found this diagram in my textbook regarding the process of spermatogenesis. But, I doubt if the labelling done is correct or not. Especially, I can't figure out any difference between the cells ...
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34 views

Does adenylate cyclase stimulate or inhibit acid secretion in the stomach?

I am confused about my teacher's notes. "Acid secretion is stimulated by ACh, gastrin and histamine. Histamine stimulates adenylate cyclase which increases cAMP production." When I looked this up ...
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1answer
84 views

Polar renal scarring in pyelonephritis?

Why does infection and scarring occurs at poles in Vesicoureteric reflux but not in Obstructive pyelonephritis? It is said in Robbins that, it is due to polar papillae being flattened or concave ...
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What causes dreams to happen?

I've heard that dreams can be influenced by what happens in our daily lives. There are many theories about why we dream, but no one knows for sure. Some researchers say dreams have no purpose or ...
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108 views

What exactly does Curare do to the peripheral nervous system?

so, I was told: If you give them the right dosage it'll wear off within an hour or two. It was used for veterinary stuff until they tried it on a human and realized it only paralyzed you and didn'...
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Why does entonox slow down cap refill

After receiving entonox a gentleman's cap refill slowed down to 4. What would so this. I was told entonox switches off the receptors but I don't understand what happens and why
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60 views

Is a large tumor is more likely to develop hypoxic regions?

It is known that cancerous tumors in humans can develop hypoxic regions where no blood nor oxygen arrive to some volume of its cells, creating a dead lump inside or around the tumor. See Wikipedia - ...
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Regarding detection of pregnancy during post mortem

Is it possible to detect pregnancy in a woman who is dead considering the fact that she did not a have a showing belly.
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45 views

If fully colorblind people only see shades of white,gray, and black, does that mean that the colors black, white, gray are colors humans can’t see? [closed]

And since the brain can be tricked to thinking that objects with mostly black and grey gradients are moving, like optical illusions, does that mean motion has a color?
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Is it ok to keep primers at 4 degrees?

I reconstitute my primers in nuclease free water ( no sterilised) this morning and I forgot them at 4 degrees, acording to the instructions, they should be storage at -20 after the reconstitution. I ...