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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1answer
37 views

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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18 views

Why do I have 95% of chimpanzee's DNA, and only 2% of Neanderthal's DNA?

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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22 views

Human Biology 2A Study Guide/Supplement [on hold]

I'm a sophomore in college and wondering if anyone knew of a study Guide or handbook that supplements the Essen Cell Biology textbook, 5th Edition, Alberts, W. W. Norton & Company, Inc. I just ...
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1answer
2k views

What is the difference between Amino acids from blood and urine?

I would like to understand the difference between different tests for Amino Acids. Any blood laboratory offers amino acids tests using 3-4 methods Blood serum Urine Random Urine 24 hour (all the ...
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17 views

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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12 views

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
44 views

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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2answers
5k views

What happens to lactic acid I eat?

Let's say I drink some Kefir Milk, what happens to the lactic acid in the Kefir Milk that has entered my digestive system?
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2answers
35 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 ...
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1answer
1k views

Is it possible to have sleep paralysis while sleepwalking?

At least from a conceptual level, these two disorders don't conflict. The effect of sleep paralysis is being conscious while having the inability to consciously direct motor functions. Sleepwalking is ...
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How to not hear deliberately? [closed]

Is it possible that, we can control what to listen and what to not? Example, we can control our sight, if we wish to see, we see that object; if we don't wish to see, we can close our eye without ...
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1answer
25 views

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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2answers
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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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1answer
63 views

What is a living homo sapiens? [closed]

https://en.wikipedia.org/wiki/Homo_sapiens I am asking to see if the human zygote should be considered a living homo sapiens. I want to know the sufficient criteria that define the living homo ...
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4answers
32k views

How many genes do we share with our mother?

Somewhere I have read we share more than 99% of our genes with every other other person and 98% of our genes with chimpanzees. What does this mean? Don't we share 50% of our genes with our mother and ...
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22 views

Why does our bones break or strain before our muscles when we fall?

I have seen many people breaking their bones by falling from high buildings, most of them underwent surgery after that , but i have never seen a single case of broken or strained muscles, they never ...
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1answer
39 views

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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2answers
908 views

Which are the last cells of the human body to die?

When somebody dies, which are the last surviving cells of his/her body? Those of hair, nails, or some other obscure but resilient cells? Shedding light on why and how they are so vital might boost ...
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46 views

How much DNA do humans share with their first non human ancestors? [closed]

As far as I understand, by reading this Hominini Australopithecus , our last ancestors are one of the australopith species evolved into the genus Homo. By taking DNA sample of bone fossils it's been ...
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1answer
65 views

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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30 views

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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1answer
93 views

Why spermatogenesis is an independent process while formation of ovum is dependent on fertilization by sperm?

At the time of ovulation,secondary oocyte is arrested at Metaphase II and goes into the fallopian tube.If fertilization occurs, sperm binds with secondary oocyte and releases Anaphase promoting factor ...
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1answer
37 views

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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What's a “constitutionally small penis”?

I'm reading some urology papers and came across one involving penis growth (Kim & Song, 2008); here's an intro passage that I'm confused about: A total of 58 patients with constitutionally ...
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40 views

Have a biology question based on human life or existence

Why must we consume life to exist. I have even read at this link (Can humans survive without consuming life?) That when cells die in our stomachs we reuse them or absorb them. Does this mean that at ...
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2answers
6k views

Is there any biological reason that professional swimming is dominated by white people? [closed]

I suppose that the question should be turned around to "Why is it extremely rare to see black people competing in professional swimming?" because it is the absence of this phenotype while watching the ...
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0answers
15 views

What is the maximum electric current a human can survive?

Many sources say that currents between 100 and 200 mA are nearly always lethal because they cause ventricular fibrillation, while higher currents cause cardiac arrest and burns but can be survived ...
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2answers
24k views

Why aren't we allowed to refreeze previously thawed breastmilk in refrigerator?

https://www.breastfeeding.asn.au/bf-info/breastfeeding-and-work/expressing-and-storing-breastmilk Previously frozen— thawed in refrigerator but not warmed 4 hours or less (ie the next feeding) ...
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2answers
8k views

Why can't we grow more teeth?

A similar question but about teeth healing themselves is Do teeth have the capacity to heal?. So I understand that teeth have the capacity to heal themselves to a certain degree. It appears to be ...
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0answers
13 views

Why are Neanderthals considered a separate species from Homo sapiens? [duplicate]

Why are Neanderthals considered a separate species from Homo sapiens? They crossbred and had fertile offspring.
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2answers
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Why isn't the human zygote considered a human life how is a living anatomically modern human defined biologically?

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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3answers
2k views

Are humans capable of both anaerobic respiration, and lactic acid fermentation?

Are humans capable of both anaerobic respiration, and lactic acid fermentation? And if so, when do they do each? I understand that the difference between respiration and fermentation is that ...
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1answer
34 views

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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1answer
19k views

Difference between intervertebral and vertebral foramina

In the human spine, what is the difference between intervertebral and vertebral foramina? Is it just a matter of perspective and do they refer to the same thing or are they different?
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2answers
12k views

What is the maximum altitude where humans can survive?

What is the highest altitude that a human can survive without being pressurized? Let's assume that oxygen and heat/insulation are not the limiting factors? Why I asked.
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1answer
31 views

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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3answers
3k views

How are our senses dimmed during sleep?

Our senses are not as sensitive during sleep compared to wake. There is an arousal threshold during sleep that only when it is overcome will it wake a person up. My question is how is this arousal ...
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3answers
641 views

How does menstruation proceed during one period?

I'm simplifying things here: A. Does a woman bleed constantly, like a drop every 10 minutes? Two hours without pad or tampon and your underwear is dirty? or B. Does a woman bleed suddenly a ...
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0answers
57 views

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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3answers
2k views

Is there such thing as “half-life” of dopamine?

If a dopamine is released at T=0 and binds to receptor D2, what determines the time when the concentration of this neurotransmitter bound to the receptor reaches half of the original concentration? In ...
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0answers
26 views

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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0answers
51 views

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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1answer
39 views

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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1answer
2k views

Why don't we build up an immunity to sore throat?

We often get sore throats once or twice a year, and it clears in a few days sometimes without any antibiotics. I was wondering why doesn't our body become immune after clearing a sore throat?
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21 views

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
41 views

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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1answer
9k views

What causes morning wood?

Sometimes men wake up with an erection in the morning. Why does this happen?
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0answers
85 views

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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2answers
130 views

Reseach on feeling pain of other people

I'm more of a tech than bio kind of guy, but I have read and learned a lot alongside of my girlfriend's education. Which is very interesting!! Currently I want to investigate : people claiming to ...
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1answer
51 views

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 ...