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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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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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Sensitivity of fever as an indicator of infectious disease

What is the sensitivity or likelihood ratio of fever as an indicator of an infectious disease? Where can I get the number from?
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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 ...
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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 ...
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Can diet, supplementation and/or drugs affect sexual dimorphism?

After puberty, can certain diets, exercise, and/or possible drugs affect masculine/feminine dimorphism in adults? We know dimorphism and/or morphology is a product of genes, but to what extent can ...
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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 ...
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Why does the ring finger not move independently?

Why is it that we need to move little finger in order to move ring finger with it? For example, put your palm on a table and fold your middle finger inside. You won't be able to move your ring finger ...
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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 ...
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Would Cu1 or Cu2 oral supplementation be most likely to aid lysyl oxidase (LOX) production?

Forgive the basic question, I'm not a biochemist but am interested in understanding the below: LOX of course is key for interlinking collagen & elastin. At the same time, it is claimed that Cu1 ...
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What are tendons made of specifically

From what I read on wikipedia they are made of collagen. Collagen is just a protein. Right? How is this collagen structured (I imagine like fibers). Aren't there cells in this fibers as well? From ...
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CELL BIOLOGY AND GENETICS [closed]

How the criteria of size, charge, polarity and hydrophilicity/hydropathy determine whether a molecule will pass through the membrane. The amino acid requirements of proteins and how they are placed ...
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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 ...
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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: {...
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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 ...
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How does prolonged exposure to high frequency noise affect hearing?

Is there any research showing how prolonged exposure to background noises, particularly high frequency noises, affect hearing abilities? Does constant high pitched noise cause damage even a low ...
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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 ...
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Haemoglobinic acid

I’ve tried searching for the structure of haemoglobinic acid but it isn’t anywhere. I was trying to find out whether H+ ions bind onto the same site as carbon monoxide and oxygen on haemoglobin or not,...
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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 ...
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1answer
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Why proximal muscle weakness is seen earlier than distal muscle weakness in Dermatomyositis?

It is said that in dermatomyositis(DM) , proximal muscle weakness is seen earlier than distal muscle weakness. It is also said that , DM is due to damage to small blood vessels contributing to muscle ...
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What is the inlet/outlet speed of air going in/out of our mouth during inhalation/exhalation

During inhalation, your alveoli expand, creating a pressure difference between the atmosphereic pressure and our lung sacks and therefore air will flow into the repspiratory airways. I am trying to ...
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1answer
47 views

Is the lac operon repressed in the presence of both glucose and lactose?

In the presence of both sugars (glucose and lactose) will there be repression of the lac operon completely? I know that more glucose means less cAMP --> less CAP --> less positive regulation, and ...
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Why do bones only get bigger horizontally? [closed]

After growth plate closure, human bones only get thicker, never longer. Why is this? Is gravity the only reason? Is it obstruction from other bones? What constrains long bone vertical growth?
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4answers
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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 ...
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1answer
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How can a child be blood type AB, if both of the parents are blood type A?

Basically, both of my parents are blood type A (both are confirmed and it's also certain both of them are my biological parents). I recently found out my blood type is AB. How is this possible? I ...
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1answer
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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 ...
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4answers
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Is there a known glucosepane cross-link breaker?

I read the following on wikipedia: There is, however, no agent known that can break down the most common AGE, glucosepane, which appears 10 to 1,000 times more common in human tissue than any ...
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1answer
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What is the distance between the insertion of the distal end of the bicep tendon and the head of the radius?

I was unable to find a source that could provide a measurement for the distance between the insertion of the distal end of the bicep tendon and the head of the radius. Does anyone know a source that ...
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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?
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2answers
62 views

Force applied to the human body

This is the basic premise of a physics question I have been attempting to solve over on the Physics SE. (I'm working on solving the actual science behind an old movie myth). How hard a punch hits ...
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2answers
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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 ...
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2answers
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Advantages of pain sensation?

The hazards of congenital insensitivity to pain (CIP) are well-known. This question is about the obverse: what selective advantage, if any, does the normal sensation of pain confer? I'm thinking of ...
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2answers
165 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?
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Does any tendon in the human body receive a high amount of blood supply?

I read on https://www.physiocomestoyou.co.uk/blog/all-you-need-to-know-about-tendons/ (mirror): [Tendons] do not have a large blood supply. Does any tendon in the human body receive a high amount ...
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Left and Right Handedness

Today I found out that the gene for being Left-handed is dominant while Right-handed is recessive. I personally am left handed and so is my father. My mothers father is also left handed and I was ...
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Why did nature decide to make plasma membrane of animal cell hydrophobic?

I am taking Introductory Human physiology course on Coursera. The teacher said and I quote " the membrane of the cell is a hydrophobic barrier that prevents any charged ions or molecules from moving ...
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What part of food gives the blood red color?

Roughly, what I know is, when we eat food it goes into our: Stomach > Small Intestine > Large Intestine > Rectum. So, it just moves through a digestive pipe. What I don't understand is, what part of ...
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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 ...
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When does the brain stem appear in humans?

This article states: Once the neural tube closes, at around week 6 or week 7 of pregnancy, it curves and bulges into three sections, commonly known as the forebrain, midbrain and hindbrain. ...
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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?
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How do I tell if the mosquitos in my New York City apartment can carry Zika?

The species that carries Zika, A. aegypti, is unlikely to be found in New York. However, the related species A. albopictus is prevalent and quite concerning. So this question is focusing on A. ...
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2answers
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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 ...
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3answers
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Why we do not get hurt from HCl secreted in the stomach?

I read in my book that during digestion our stomach secretes hydrochloric acid ($HCl$). Why we do not get hurt from it? It was also said that mucous provides protection, but from where is it coming?
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Could an uncut umbilical cord benifit a baby?

How long and would there be any benefit like adding an IV line to the uncut umbilical cord after a baby is born? Can keeping the umbilical cord attached (and for how long) be beneficial or harmful ...
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Could a reed mat delay human decomposition for over three years?

Based on a discussion over at Mi Yodeya. The relevant part here is the claim discussed there that if a body is buried wrapped in reed mats, it slows its decomposition by a factor of several years. Is ...
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1answer
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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 ...
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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 ...
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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?)
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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 ...