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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Nutrition and experimental biology

We know that food in the stomach is present in the form of chyme treated with pepsin and hydrochloric acid, if we take food crush it with saliva and then treat it with Pepsin and HCl (in the lab),and ...
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Is atrial natriuretic peptide relased when we drink water?

I know that osmolarity is controlled by the hypothalamus and recover by ADH which reabsorb water. It also can be released when ECV is very low. ECV/salt is controlled by aldosterone/atrial ...
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Why isn't life expectancy normally distributed?

Lots of phenomenon in nature can be plotted onto some sort of normal distribution, and that makes intuitive sense to me (such as human height). Why then, does global human life expectancy drop off so ...
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Are there any benefits/disadvantages/traits from having a permanent lower core temperature?

My body temperature as far as I remember has always been around 35.6 degrees Celsius, that's a degree less than what is the usually quoted as the average temperature for humans. Are there any known ...
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Does intelligence depend more on environment than on genetic factors? [duplicate]

Many have argued that the test of IQ is simply a test of language. The application of the test consists of asking a number of questions. The person should understand the question presented to them and ...
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How much Oxygen can the Human body carry?

Basically - the title: How much Oxygen does a human body carry at a single point? What have I tried: A friend of mine has done some calculations and came up with the following numbers. Neither of us ...
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Does any tendon in humans receive a high amount of blood supply? Or is the property of not receiving a large blood supply a constant across tendons?

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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Apply ficks law to explain biological examples of diffusion [closed]

Apply ficks law to explain biological examples of diffusion. I have researched this question and found the equation for ficks law rate of diffuion= area of diffusion surface x difference in ...
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Is it possible to buy a DNA sample with a specific mutation?

I would like to test a genotyping method (ARMS) on a specific human snp (heterozygous or homozygous ). Unfortunally, we do not have any dna samples with the mutation. Is it possible to buy somewhere a ...
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Can stress and arousal be independent?

I'm trying to figure out if it's possible to have a stress response without being initially, or simultaneously aroused. I'm defining stress to be physiological stress (ie. release of cortisol) and ...
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1answer
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What are the genetic basis for further classification of human beings? [closed]

According to anthropology, human race further gets divided in Caucasians, Mongoloids, Aboriginals, Eskimos, Red Indidians and Negro's. How far, is this classification, though maybe anthropologically ...
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What are areas of the body where stab wounds are not lethal? [on hold]

I do not know if this stack exchange is the most appropriate one for this question, and if not I apologise and hope it will be redirected to the correct stack exchange. As title indicates, I'm ...
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How to overcome the tiredness feeling which come after studying 60-90 minutes [closed]

I am preparing for a examination called JEE which have physics, chemistry and maths questions in it. I study in slots of 10 minutes, for the first 9 minutes I study and and than completely rest for 1 ...
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How long can a human survive in a vacuum? [duplicate]

I’m curious how long a human could survive in a vacuum, how he/she would die, and if an O2 mask or tight-fitting clothing would help.
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Can we drink water before brushing teeth? [on hold]

It is written almost every where to drink water in the morning empty stomach but should we do it before brushing or after brushing?
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Could ions inside lungs produce hydroxyl?

I am not proficient in either biology or chemistry. However, I have a question which I can't find answer to. It seems to belong somewhere between chemistry and biology. I apologize for any errors and ...
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Can we “learn” reflexes?

Can we force our bodies to react to situations faster than our brain can think about them? Some reflexes I can think of off the top of my head: knee jerk reflex retracting hand when touching a hot ...
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Clone instict of life [closed]

If we create 2 clones of a person, how would they behave to each other? I mean, would they protect each other at all costs or work as separate beings?
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1answer
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Does the 1:1 sex ratio at birth apply to every human pregnancy or is it a statistical average?

Are there genetic factors that biase the sex ratio of offsprings for each person but average to 1:1 for the entire human population, or does the 1:1 ratio apply to every single fertile person?
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What do we mean by MHC molecule diversity? Does each human have a variety of MHC molecule isoforms?

I'm going to try and explain what I think I know From what I understand, MHC/HLA molecules present peptides to T cells. To be able to present peptides from a wide variety of pathogens, they need to ...
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Adenosine Triphosphate is used as energy supplier why not GTP / CTP / TTP [duplicate]

All are having Triphosphate ATP / GTP / CTP / TTP Why only ATP is used as an energy supplier?
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2answers
2k views

Can UV radiation be safe for the skin?

It is well known that UV radiation can damage the DNA and generally harm our skin. We also know that UV radiation helps on the production of melanin and Vitamin D. From what I could find, the DNA ...
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1answer
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Does body absorb nutrients less efficiently if we ingest the same amount at the same time, opposed to spreading over a larger period?

I would like to understand if ingesting a certain amount of nutrients will result in different absorption from my body, depending on whether I ingest that amount spread over time or everything at once....
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Is attractiveness linked to total population of sexes?

I ask due to linking in with some pre University research. I am seeing if there are studies and if you can link them to me about if The rating of attractiveness per female is more if there is less ...
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What are the sufficient criteria that make an entity a living homo sapiens? [closed]

When I say criteria I mean like x biological functions or y genetics. If it were to be appearance,anatomy. A corpse completely looks like a man. Moreover a person who has had their 4 limbs amputated, ...
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Why do I have 95% of chimpanzee's DNA, and only 2% of Neanderthal's DNA? [duplicate]

Excuse me if it is a question with a simply answer, but I don't understand these discoveries, looking a discrepancy from my unknowledge of genetics: I have 95% of Chimapanzee's DNA, and, I have [...
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2answers
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What could humans do to “see” what dogs smell?

We're able to see a lot of things using computers that we can't see normally: yellow-green, UV light, X-rays, etc. What do we have that harnesses the ability to "see" what dogs smell (e.g., harnessing ...
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How does the cardiovascular system improve upon repeated, strenuous exercise?

New here, hopefully this is the right place to post this question. It's widely known that repeated, strenuous aerobic exercise gradually improves the capacity of one's cardiovascular system — $\text{...
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Are cold weather tolerance and spicy food tolerance related physiologically?

If a person grew up in a cold place they happily walk outside in winter in short sleeves and shorts in places with mild Winters while the locals are bundled up in thick jackets. Spicy food with ...
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1answer
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Are casein proteins in UHT milk digestable for infants or toddlers?

As a novice cheesemaker, I have read that Ultra High Temperature prosessed milk is unsuitable for cheesemaking, as casein proteins are denatured and cannot be curdled with rennet. I have verified that ...
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What separates humans from other animals?

It is clear that humans are distinguished from the other species on Earth, but what specific features are the cause? Other animals like chimpanzees have been shown to have consciousness and some self-...
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1answer
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Which chemokines are being produced by melanocytes?

I am looking into Vitiligo it's an autoimmune disease that results in apoptosis of melanocytes due to misfolded protein accumulation. It also dramatically increases breast cancer rates (600 times) ...
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Why can early embryos survive freezing?

According to this Blastocyst & Embryo Freezing in IVF Embryos can be frozen at the pronuclear stage (one cell), or at any stage after that up to and including the blastocyst stage (5-7 days ...
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Why isn't the human zygote considered a human life how is a living anatomically modern human defined biologically? [closed]

It has 46 chromosomes by default when healthy(Differences almost always are pathological) and has almost every biological functions, processes a Newborn or and Adult person has. It even invades ...
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Cerebral/Cerebellar Cortex versus Deep Nuclei

I have troubles using the terms Cortex & Deep Nuclei, and 'Nuclei' in general. From what I understand, a brain has '3 matter types in accordance to anatomical locations' Superficial Grey matter - ...
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Sexual Reproduction in Humans

Is the human egg cell (ova) considered motile? We know that is is not actively motile but it is transferred via the fallopian tube to the uterus. Does that make it motile?
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Protein inhibitory process

I usually find substances that activates proteins, like ApoA-I, but I don't find substances that inhibit it. So in an experimental design, could I consider the absence of a drug that directly acts ...
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1answer
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What is a deep exhalation/inhalation?

I tried to find the academic definition of deep exhalation/inhalation but found nothing special. I speculate that the correct definition is as follows: • Deep ...
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Are your finger muscles and tendons interconnected?

Are finger muscles and tendons interconnected? If they are interconnected, then if i exercise one finger will it train the other fingers since they are interconnected and share the same muscles in the ...
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Optimal carbon dioxide concentration range for the human body

Previously I had thought the maximum concentration of CO2 for human health to be given by the ‘Pettenkofer CO2 level’ with a maximum of 1000 ppm. But according to this post a growing body of ...
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Do tenocytes move around in a healthy tendon or do they stay at the same location?

The 2018 study {1} mentions that: The healing process of injured tendons includes tenocyte migration which occurs from intact regions of tendon into the wound site. Do tenocytes move around ...
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1answer
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RE: Fasting gastric pH vs Normal gastric pH

If fasting gastric pH values are more acidic then why is it recommended to eat no more than three hours before bed time to prevent reflux. It seems at some point during sleep the stomach would become ...
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Does vitamin D affect melanin concentration?

I am aware of the affect on vitamin D production by melanin (in sunlight) but I can not find any information regarding a reverse connection.
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What percentage of the human genome hasn't been sequenced yet? If percentage estimates aren't precise, why is it difficult to estimate?

What percentage of the human genome hasn't been sequenced yet? I have read different estimates, e.g.: https://www.genome.gov/human-genome-project/Completion-FAQ (mirror): "In the April 2003 version, ...
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Why do calcific tendinopathies mostly affect the supraspinatus tendon?

I read on {1}: Calcific tendonitis or hydroxyapatite deposition disease is a common disorder and the site of occurrence is around the shoulder mainly within the supraspinatus tendon and at a ...
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For how long is the gene expression altered in tenocytes' nuclei following changes in mechanical load, and which genes are affected?

I read in {1}: The matrix is far more conspicuous than the cells. However, it is now widely recognised that the cellular elements hold the key to understanding development, repair and the ability ...
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What causes tenocytes to migrate from intact regions of tendon into the wound site, and how do they move?

The 2018 study {1} mentions that: The healing process of injured tendons includes tenocyte migration which occurs from intact regions of tendon into the wound site. What causes tenocytes to ...
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1answer
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What differentiates neurons in different parts of the brain?

For example: what makes a neuron in the hippocampus of the brain different from a neuron in, say, the amygdala, or the frontal lobe, or anywhere else in the brain? Do neurons in different parts of the ...
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1answer
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Heritable immunity and smallpox vaccination [duplicate]

As I understand it, lack of heritable immunity caused smallpox to wipe out certain communities of native Americans. If vaccination conveys heritable immunity to a population, shouldn’t this make ...
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How does the structure of tendons change as they become stronger?

I understand the basic structure of tendons, but I wonder how a tendon becomes stronger via exercise. Do the collagen fibers become more aligned/numerous/dense/etc.? Is the tendon expected to become ...