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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27
votes
3answers
8k views

Can humans ever directly see a few photons at a time? Can a human see a single photon?

I am not asking the following question: Can humans ever see a photon in the same way we see a chair? My question is: Can a human retina respond to a single photon? If so, how does this happen and why ...
4
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1answer
107 views

Explain to a layperson how cigarettes smoke might cause cancer

I have a very intelligent friend who is a light smoker, and also a Biology layperson. I wondered whether understanding exactly how cigarettes smoke can cause cancer, might encourage him to smoke less ...
1
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0answers
48 views

What causes a tendinopathy to calcify?

I read in this 2012 research paper {1}: The aetiopathogenesis of CT [calcific tendinopathy] is still controversial, but seems to be the result of an active cell-mediated process and a localized ...
0
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0answers
28 views

For how long can the heart be in asystole and then restart itself?

The medication Adenosine is used for the treatment of some abnormal heart rhythms. However, according to Wikipedia, it can cause asystole for a few seconds: Because of the effects of adenosine on ...
0
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0answers
25 views

How important is getting enough glucose for maximal brain performance / cognition?

I know from many studies that have been done, that resting versus active use of the brain has relatively similar overall energy expenditure levels. On the other hand, however, we know that the brain ...
0
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0answers
54 views

Why are isometric contractions more analgesic than isotonic contractions for tendon pain?

According to a randomized clinical trial {1}, isometric contractions are more analgesic than isotonic contractions for tendon pain. The explanation they give is as follows: The antinociceptive ...
1
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1answer
91 views

How can space travel affect women’s fertility?

From Time: The reasoning behind the prerequisite, according to officials, is that spaceflight could potentially harm the women's fertility. How can space travel affect a woman’s fertility?
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0answers
34 views

How do painkillers prevent shock?

I was reading about the Placebo effect and came across this little story: The roots of the placebo problem can be traced to a lie told by an Army nurse during World War II as Allied forces ...
0
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0answers
62 views

Does the Chorion Completely enclose the Amnion in Humans

When a human baby is born "en caul" (aka enclosed in the amniotic sac) the amnion detaches from the chorion and the baby comes out in the sac with the chorion still attached to the placenta. If the ...
2
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0answers
37 views

How does the strength of 3D printed tendons compare to original tendons?

There have been some attempts such as {1,2} to 3D-bioprint tendons. How does the strength of 3D-bioprinted tendons compare to original tendons? I am mostly interested in human tendons. References: {...
0
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2answers
39 views

Does loss of dopaminergic neurons totally eliminate voluntary muscular control?

Breathing is a function that is not only autonomic, but can also be temporarily overridden and placed under voluntary control. In fact, you are now breathing manually. Now, suppose that someone has ...
0
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0answers
18 views

Why does the ratio type III collagen:type I collagen increase after a tendon injury?

I read on {1}: Type III collagen has accumulated at the rupture site [of human Achilles tendon] probably due to microtraumas and the subsequent healing process. […] The increased content of type ...
2
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1answer
108 views

Blood acidity and bones

By consuming acidic foods, could one cause their blood to become acidic and therefore cause an acid+base reaction between their blood and bone? I ask this because i recently discovered bone is a ...
3
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1answer
41 views

Why does cholesterol need to attach to proteins to travel through the blood?

I guess the deeper question is: what makes it possible for proteins like those part of HDL and LDL to move through the bloodstream?
11
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2answers
3k views

Where can I find the list of all tendons in the human body?

https://www.healthcentral.com/article/aging-can-take-major-toll-on-womens-tendons (mirror) claims that: There are about 4,000 tendons throughout the body. This claim is echoed by a fair amount of ...
1
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2answers
201 views

Why are (some) human men sexually attracted to female breasts?

Many human men are sexually attracted to female breasts. Is there an evolutionary reason for this?
3
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1answer
69 views

Does eating hard food really cause wisdom teeth to erupt properly?

According to the article Bad molars? The origins of wisdom teeth, in our evolutionary history, people were eating harder food like nuts and had unimpacted wisdom teeth. Later, that article appears to ...
0
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2answers
42 views

Are there any non-pathogenic gram-positive bacteria in human gut?

I wish to know if there are any non-pathogenic (not even opportunistic pathogen) gram-positive bacteria in the human gut? Is there any reference that shows there exists a non-pathogenic gram-positive ...
38
votes
4answers
11k views

Can a person survive on blood in place of water?

This question: Can you get enough water by eating only fish? asks if a person could survive on fish alone. Can a person survive on fish and/ or blood alone of any species if stuck at sea or animal ...
2
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0answers
45 views

Why can dogs hyperventilate without consequences like humans?

During the heat of summer, dogs usually breathes very fast, like 100 times per minute or more. If humans do so, we will experience an array of negative effects like dizziness, finger tingling or ...
3
votes
1answer
87 views

How does the human body extract energy from ethanol?

I was talking about alcohol and obesity with a colleague. I always thought the only cause of that is the sugar that is found in most alcoholic beverages. But my colleague pointed out that ethanol ...
0
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0answers
14 views

How are codocytes or target cells formed?

How are codocytes or target cells formed in conditions like Thalassemia? And why do they appear like a target(as in why is there a central red surrounded by pallor surrounded by red?)
0
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0answers
109 views

What is the significance of different types of papillae present on tongue?

Fungiform, Circumvallate, Filiform, Foliate Papillae are present on the surface of the tongue. They have a role in increasing surface area for taste buds that can be accommodated on the tongue. Each ...
0
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0answers
24 views

Are girls more often first born compared to boys in families with two children?

When there are two children, one girl and one boy, in a family are girls more often the oldest? If so what causes this?
2
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2answers
103 views

Why is HPV vaccines targeted for preteens?

Why is human papillomavirus products targeted to children before sexual activeness? Could all ages benefit from this vaccine even if they may have or have not contracted a form of HPV to prevent other ...
-2
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1answer
43 views

is it possible for a son to inherit an allele on a Y chromosome?

Obviously, the only way for one to be male is to inherit the Y chromosome, but are there alleles on the y chromosomes? Or is it just automatically the recessive trait without an allele.
4
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1answer
92 views

Is returning cholesterol to the liver really performed by HDL?

Various answers in biology SE, including two quite upvoted ones (1, 2) claim that (in humans) returning cholesterol to the liver is done by HDL. If I understand correctly, Wikipedia's Reverse ...
1
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0answers
60 views

Can one assess muscle strength through imaging (e.g., MRI)? If so, though which type of imaging and how accurate is it?

Can one assess muscle strength through imaging (e.g., MRI)? If so, though which type of imaging and how accurate is it? On How does muscle size relate to strength?, I read this answer from Moses (...
0
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1answer
110 views

Is drinking your urine an effective way to stay hydrated in a hostile environment?

There are quite a few stories about people trapped or otherwise incapacitated resorting to drinking their own urine in an attempt to stave off dehydration, ignoring the long term consequences, my ...
0
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1answer
45 views

Understanding genetic similarity in humans [duplicate]

I was reading "Blueprint" by Robert Plomin (online preview on webpage) and got stuck when I got to these two sentences in the prologue: "We are the same as every other human being for more than 99 ...
1
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1answer
29 views

Is “muscular attachment” synonymous to tendon? (when talking about the insertion of glutei medius and minimus to greater trochanter of the femur)

I have read the following two terms in an MRI report (both points refer to the insertion of gluteus medius/minimus to greater trochanter of the femur): mild degeneration of the muscular attachment ...
7
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2answers
2k views

Is NMDA produced in the body?

On the wiki page for NMDA it says that NMDA is a synthetic substance that mimics glutamate. So why does the body not use glutamate instead of NMDA? Also how is it possible that our body can produce ...
2
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2answers
61 views

Is it impossible to increase skeletal bone mass, as opposed to just bone density? [closed]

I've heard exercise and resistance/strength training increases the density, but doesn't increase mass. So basically, experimentally or theoretically possible at least, can modern science do this/is it ...
2
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0answers
43 views

Could certain drugs enable one to consistently eat above TDEE or BMR without fat gains?

I heard anabolic steroids and stuff like DNP and ephedrine and etc. can somewhat enable one to eat more and get away with it without much or any fat gain, despite eating more than the body would ...
1
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0answers
45 views

Does the molecular composition of human body change after a period of time?

I was discussing change in human biology over time and my two in-laws charged in saying, "we're molecularly different after x". I didn't pay attention to what time period they exactly mentioned (hence ...
0
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0answers
22 views

Does the human body absorb any of the humidity in the environment when dehydrated?

I was walking in the rain and feeling thirsty, and I wondered if when the human body is dehydrated it does absorb any of the humidity in the environment by itself.
-2
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1answer
138 views

How much does biomagnification affect human beings?

It is known that the effect of biological magnification increases with higher trophic levels. Since, we are at the top of the food chain, how much are we affected by it? Is there any proof of humans ...
0
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1answer
102 views

Coronary circulation

It is said that the coronary artery that gives the posterior descending artery(PDA) determines if the heart is right dominant(most cases) or left dominant. Is there any reason to this? Why PDA?
1
vote
1answer
184 views

Where does the gluteus medius attach to the greater trochanter compared to the gluteus minimus attachment?

Where does the gluteus medius attach to the greater trochanter of the femur compared to the gluteus minimus attachment? Is it above, below, next to it, etc.? Ideally I'd like to know the distance as ...
1
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0answers
27 views

Techniques of molecular medicine/biology for aesthetic medicine?

Are there scientifically valid methods (possibly in the developmental stage) that can be used for aesthetic medicine. Usually surgical of physical therapies are used for aesthetic medicine, but ...
4
votes
0answers
30 views

What phosphorylates tau protein & and what causes tau to be phosphorylated?

I want to know what phosphorylates tau protein and its 6 isoforms. I know kinases cause phosphorylation events, and in tau it can be phosphorylated in a healthy neuron in the trans conformation, but ...
0
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0answers
39 views

Left or Right hand fingerprints relation between people

I am making a machine learning program for a project at school, where I would like to classify fingerprints (well depending on your answer I will have to change it) depending on wether its of a left ...
2
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0answers
32 views

Do tarantulas and humans have the same mechanism for growing hair?

There's hair on my arms. Tarantulas also have hair on their arms. Is this the same type of hair?
0
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0answers
11 views

Can disorders involving involuntary muscle twitches and spasms have a hypertrophic and increased residual muscle tension effect?

Meaning disorders specifically like myokymia, myoclonus (positive and negative) and fasciculations. From the section of the literature I've seen, sometimes passing mentions are made when the disorder ...
1
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1answer
41 views

What is the darkest color human bowel movement can become? [closed]

I assume a healthy human, with usual nutrition, without using any drugs or supplements.
1
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0answers
27 views

What causes bio electricity? [closed]

When it is said that “electrical impulses sent from the brain” how is this charge flow produced?
1
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1answer
31 views

Can motor neurons in the brain stem start movements?

Supposedly (consciouss) movement is started in the cerebral cortex. But some time ago I've read a research which stated it might be possible some movements (not specified which ones, probably mean ...
1
vote
1answer
9 views

Are the processes on afferent neurons that go from the sensory receptor to the cell body considered axons or dendrites?

References on pain fibers say impulses move along axons to the CNS, but I thought that by definition axons carry impulses away from the cell body.
2
votes
1answer
64 views

Does every protein starts with Methionine amino acid [duplicate]

During process of protein synthesis we need AUG Codon to start translation .As we know this codon codes for Methionine amino acid so can we say that every protein starts with Methionine amino acid ?
1
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0answers
39 views

How hot water burn works?

At age of 6 I accidentally dipped my hand into a boiling indian curry(Sambar) which was in a large pot. I got a Boiling Water Burn(Just like in the picture but with a little more radius) in my hand ...