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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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Do you have nerves on the outside of your skull?

I have a spot on my skull that feels like a nerve or blood vessel. I know that there are many to the brain, however, it is the only one I have ever felt. So do we have nerves or blood vessels on the ...
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0answers
14 views

Why does the exercise level impact the nail growth rate?

I read on https://en.wikipedia.org/w/index.php?title=Nail_(anatomy)&oldid=863800434#Growth: Actual growth rate is dependent upon age, sex, season, exercise level, diet, and hereditary factors. ...
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0answers
14 views

What conclusions can I draw about the size, charge, and shape of messenger molecules?

Molecules such as cAMP or Inositol trisphosphate are used in organisms as messenger molecules that make things happen when they are supposed to happen. These molecules are usually big, but not too big,...
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1answer
10 views

Ciliated Epithelium & Goblet Cells Lining The Trachea

My book states this - The cells produce mucus that traps particles of dirt and bacteria in the air breathed in. The cilia on these cells move this debris up the trachea and into the stomach. Isn't the ...
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1answer
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Cross-species infections

I’ve heard that HIV developed from SIV, etc. I’ve also heard that most species (including most monkeys) can’t get a common cold like humans. So then what causes infections to be able to travel ...
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0answers
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diversity of races [closed]

How are africans the most diverse race if all africans look alike to me? besides some being short or tall, sans being brownish but all the rest black. I don't see much racial diversity phenotypically ...
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1answer
60 views

Is there a simple incision that would render a man impotent?

I’m writing a novel in which two women (one of whom is a doctor) take revenge on a rapist by performing surgery on him. What would be the simplest but most effective way of causing permanent and ...
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0answers
45 views

Best method to storage human DNA i a freezer?

I want to collect human DNA and then store it for as many years as possible, that is at least 10 years. I have a freezer at home that can hold down to minus 31 degrees celcius (-22 Fahrenheit). ...
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13 views

What are the perfect conditions for colon cancer proliferation?

Given the modern knowledge of anatomy and biology what are the things one must do in order to maximize colorectal cancer proliferation?
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3answers
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Why do hot water baths affect only males' fertility? Why not females'?

Here is the link where urologists are warning men not to take hot water baths. Why does it affect only males' fertility? Why not females also?
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2answers
40 views

Why does resting potential not become continually more negative?

(Firstly, I know this is similar to other questions, but I have read those answers and they do not really cover this topic). My understanding of resting potential: action potential is not being ...
5
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1answer
74 views

Why Is Gray Matter Gray?

There are different people giving different reason for this popular one 1) white matter is mylinated .this reason was given in reference and few website like this while others say 2)cell body ...
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1answer
26 views

Is there muscle hyperplasia or hypertrophy after surgery?

After exercise there is hypertrophy only. I am curious, if a surgery removes muscle, will there be hyperplasia or hypertrophy to restore it?
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2answers
100 views

Are the first humans black

I have been doing some studies and I believe humans where black before they were white. Black has the ability to create all colors where as white derives from no color so white couldn't have been ...
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0answers
7 views

Can you improve your intelligence by practising? [migrated]

According to this article https://www.nature.com/articles/ng.3869 your intelligence as an adult is to 80 % determined by genetics: Despite the well-known difference in twin-based heritability for ...
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2answers
42 views

Infant immunization

I know that polio vaccine consists of small dose of polio virus itself, which activates body's immunity against the disease. An infant is given a no of vaccines including chickenpox, tetanus, ...
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1answer
28 views

What is (roughly) the net charge of the DNA in an average human cell?

I was wondering about what general range for the net charge of DNA in human cells is in Coulombs. I imagine that kind of thing would be hard to measure but could be approximately calculated/estimated....
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0answers
28 views

why our nails and hair grow even when they are cut?

Our hair and nails grow even when we cut them.This has a coincidence with the growth of plant parts even when we cut them of.I know that my question is silly but is there any chance for the presence ...
1
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0answers
29 views

Can the natural loss of memory be modeled with a continuous function?

Disclaimer: I have little to no background in biology, so this question is based on anecdotal evidence. I've tried to spell out all of my suppositions, but please let me know if I'm making any leaps I'...
5
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2answers
74 views

Why is Cacao a stimulant?

As I write this I've just eaten a fair amount of cacao (not cocoa) powder and it's given me quite a buzz. I've googled the effects and the Internet seems to think it's somehow psychoactive although it'...
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1answer
18 views

Environment requirement for human life [closed]

I was wondering, what are the humans needs to fulfill to achieve a human colonisation on mars ? Let me explain, this is for role play game in a futuristic world where humans colonized mars. That ...
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1answer
79 views

Is it logical for someone to be allergic to the water molecule, but be perfectly fine with drinking milk since it's only 87% water molecules? [closed]

Recently this article got into the tabloids. The comments were disabled very quickly. Strange. The authos says she has Aquagenic Urticaria but it is a skin condition not an allergy, and hence wouldn'...
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0answers
14 views

Once neurotransmitters bind to its receptors, how does the post synaptic neuron “know” when to start a new action potential?

My textbook seems to gloss over this subject. Once the post-synaptic receptors are activated, do they cause particular ion channels to open, letting positive charge into the cell and inching the ...
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0answers
15 views

Why do we need to do specific physical exercices as adult when children don't need it? [migrated]

I've read this: https://www.babycenter.com/404_how-much-exercise-do-babies-need_6874.bc Why do we need to do specific physical exercices as adult when children don't need it? Why can't we as adult get ...
3
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1answer
95 views

What advantage does the pseudostratified epithelial structure type provide over squamous, cuboidal, and columnar?

I'm currently and have had difficulty receiving an answer about the role the pseudostratified columnar structure provides. I understand that that the following have their respective advantages: ...
3
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1answer
60 views

can one be infected with Naegleria fowleri by taking Steam?

will Naegleria fowleri be present in the steam molecules. Many people take steam from hot water to get relief from sinus. I read somewhere that Naegleria fowleri gets killed over 70 C. So steam will ...
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1answer
33 views

Why do neutrophils need to die after pathogen phagocytosis?

From referenced article below, neutrophils need to be removed because its granule contents and oxygen metabolites (used for killing phagocytosed pathogen) are harmful to the surrounding tissue. Thus, ...
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0answers
20 views

How long does it take fluids to make their way into blood vessels, to dilute blood volume to full after major blood loss?

So if one has a significant haemorrhage, how long will it take say for blood test results (hemoglobin and iron etc concentrations) to be impacted to full extent?. I've heard it takes multiple hours, ...
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1answer
92 views

Is Human a race? [closed]

Is it correct to say that 'humans' are a race? Will it also include apes and chimpanzees? Can I use the terms 'species' and 'race' interchangeably?
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1answer
56 views

Why do ADULTS need protein in their diet, if they are not growing? [duplicate]

Why do ADULTS need protein in their diet, assuming they are not growing? What happens to the amino acids already present in the body? Why don't our bodies conserve them?
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0answers
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Wound Healing Speed Across Soft Tissues?

I've heard that different tissues heal at different rates. Does anyone know of any attempts to measure and quantify the rates of soft tissue healing across different tissue types, or to determine the ...
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0answers
14 views

Acute calculous cholecystitis

The action of mucosal phospholipases hydrolyzes luminal lecithins to toxic lysolecithins. The normally protective glycoprotein mucus layer is disrupted, exposing the mucosal epithelium to the direct ...
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2answers
84 views

ATP production via aerobic respiration

Just started learning about aerobic respiration today, specifically Glycolysis. We were told that aerobic respiration produces 38 ATP, while anaerobic respiration produces only 2. However, we're ...
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1answer
84 views

What makes red meat less healthy than seafood, after millennia of evolving to eat meat? [closed]

We are told that red meat is carcinogen; fish and white meat are not. What make us not "compatible" to red meat after thousands of years of evolution and meat eating, and yet seafood is opposite ?
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0answers
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Why Cerebrospinal fluid is not heated for VDRL?

For performing VDRL of serum , we heat serum to inactivate complement proteins which may otherwise interfere , but why don't we do same for CSF even though it too has complement proteins in it? Is it ...
2
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1answer
40 views

Why reaginic antibodies are absent in these types of syphilis?

According to Textbook of Microbiology and Immunology 2e, Subhash Chandra Parija, pg.no; 375 These(reaginic) antibodies do not appear in early primary syphilis, latent acquired syphilis of long ...
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0answers
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Does the ratio between M and L cone cells vary in one indiviual?

Wikipedia says: The ratio of M and L cones varies greatly among different people with regular vision (e.g. values of 75.8% L with 20.0% M versus 50.6% L with 44.2% M in two male subjects). This ...
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0answers
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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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0answers
4 views

Lacrimal caruncle

What anatomical structre sits behind the lacrimal caruncle? Is there also part of the eye or something different like conjunctive tissue? In short: Does the lacrimal caruncle also covers parts of the ...
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0answers
21 views

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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0answers
31 views

How does the vagina stretch during arousal?

There doesnt seem to be any mechancial way for this to work. There is nothing hindering or pulling the vagina which would result in a shape change. There are only muscles which constrict the vagina. ...
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0answers
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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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0answers
24 views

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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2answers
97 views

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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33 views

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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1answer
70 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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1answer
82 views

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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2answers
105 views

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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1answer
35 views

İrreversible dopamine antagonist vs. Dopamine agonist

Can a dopamine agonist reverse the effects of an irreversible dopamine antagonist?
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2answers
41 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 ...