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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4
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1answer
93 views

Do human-ape hybrids exist?

Since humans and apes share up to 99% of their DNA, can they interbreed? For example, a horse and a donkey seem to be just as distantly related and produce offspring. Mules, however, are sterile. ...
2
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0answers
52 views

Is there any biological support for the concept of “chakras”? [closed]

Is there any support in modern biology for the ancient concept of "Chakras"? I've seen the concept of 7 chakras linked to the major endocrine glands in the human body (pineal,thyroid, adrenal, ...
0
votes
1answer
101 views

Does the DNA of a tadpole change after it becomes a frog?

Does the DNA of a tadpole change after it becomes a frog? In other words what changes take place as a tadpole becomes a frog, and does this metamorphosis affect the DNA in any way? I would appreciate ...
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0answers
48 views

How many mitotic divisions do haploid cells undergo before fertilization?

Background This question is about human physiology and gametogenesis. A spermatozoid is not necessarily the direct "offspring" of diploid cell. Stated differently, a spermatozoid cell can be the ...
-1
votes
1answer
163 views

Our muscles give us the ability to move our arms but…? [closed]

I have a strange question, but let me tell you something first. If you think of this carefully, then you realize something, please try this right now: Contract your muscles only so that your arms ...
1
vote
1answer
29 views

Difference between pulse and blood pressure

I'm a very naive and biologically illiterate person, and from what I've read on the internet I'm not really sure I understand the difference between pulse and ...
-5
votes
1answer
91 views

Why do fingers swell during cold winters?

When exercising, tissue in the hands may swell. This may be caused by the muscles generating heat, which leads to blood being pushed to the vessels closest to the surface of your body to dissipate the ...
3
votes
1answer
85 views

Human bone density and Brown Bear bone density?

It is stated on this website that the density of a Grizzly bear bone is ten times our own. And since I am not into biology at all, I am confused as I don't understand the meaning of bone density here. ...
2
votes
1answer
44 views

Help reading gene markers

I'm sorry if "gene markers" is not the correct word. An edit could be appreciated but I don't study in an English speaking country unfortunately. Question overview: In a family, there is a genetic, ...
2
votes
2answers
38 views

Help reading chromatogram

A genetic variation is found in this chromatogram: It says that the "reference sequence" is the top line and that I can use the general genetic code to find the reading frame. I can see that there ...
5
votes
1answer
93 views

Why do we get tired [closed]

At the end of a day full of work, it is general for people that their eyelids start to feel heavy. Laziness takes over and we begin to yawn. We all know that we're tired at that time, but why people ...
5
votes
1answer
97 views

What's a mouth ulcer/canker sore “made of”, and why do they develop?

Mouth ulcers are red/white rings with a crater. They are sore and last for 7-10 days. What I want to know is what they are 'made of' - i.e., what is the ring filled with, and why is the centre crater ...
2
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0answers
45 views

The ring formation of ringworm

I know ringworm is caused by a fungus on the skin, nails or scalp but what causes the rash to form as a ring instead of like a normal spread out rash?
5
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0answers
41 views

Do blood glucose “spikes” contribute to insulin resistance, or is prolonged elevation required?

There's increasing public discussion about the health risks of chronic insulin resistance* (IR). In many cases there's a focus on high glycemic index foods that "spike" your blood sugar, which implies ...
0
votes
1answer
112 views

Why should or shouldn't we allow the human body to take its natural course? [closed]

For example, when you are sick but don't feel thirsty, this could be due to baroreceptor reflex that is attempting to readjust salt and water balancing. Why shouldn't a patient be left thirsty and ...
8
votes
1answer
525 views

Why do people feel pleasure when using roller coasters / centrifuges?

The feeling when using an amusement park unit is usually a pleasure. Why is it not a pain instead? Are there advantages, from an evolutionary point of view, in loving this potentially dangerous ...
3
votes
1answer
115 views

Why do people in the scientific community use terminology such as renal, hepatic, cardiac instead of kidney, liver and heart? [closed]

Why is there the need to map these everyday words into another set of words, it seems to complicate matters. Is it done mostly out of tradition or is there some logical basis to it?
0
votes
1answer
61 views

Survival with only water but no food [duplicate]

How long can the average, healthy adult human survive with only water?
1
vote
2answers
73 views

Can leukopenia in a person with an otherwise normal immune system lead to non-infectious diseases in the long-term?

If a person has developed leukopenia as a side-effect of long-term use of anti-convulsant medications and his/her immune system appears normal otherwise (does not get infections any more often than a ...
4
votes
1answer
43 views

How can human infants express chymosin with only a pseudogene at their disposal?

I read on the Wikipedia article about Chymosin http://en.m.wikipedia.org/wiki/Chymosin It stated that chymosin is produced by gastric chief cell in human infants. But it also stated that human only ...
0
votes
1answer
22 views

Beta oxidation of saturated fats

In my text book there is an example of a 18 carbon long fat and it says that it can run 8 laps of oxidation. I don't understand why it doesn't run 9? 2 are removed each cycle? Thanks.
1
vote
1answer
50 views

Why use creatine phosphate?

We use creatine phosphate as an energy storage to resupply ADP with a phosphate group as our muscle cells only contain about 2-5 mM ATP. But why doesn't the muscle cells just keep 20-30 mM ATP instead ...
0
votes
0answers
38 views

Why doesn't the body optimize how many fatty acids it burns?

Ketone bodies are produced due to an excess of fatty acids being burned (accumulation of acetyl-CoA) so my question is: Why doesn't the body simply regulate how many fats it burns so it doesn't have ...
2
votes
1answer
34 views

How are ketone bodies used?

While searching for literature on ketone bodies, I can only seem to find how they are synthesized, but not how they are broken down. I'm looking for the series of events with enzyme names and ...
9
votes
1answer
335 views

Why gluconeogenesis?

It seems quite pointless to me. Why would I want to use energy to create a molecule that I can then use again for less energy? It seems only to serve as a complete waste of energy to me? Can someone ...
3
votes
1answer
34 views

NADH shuttles - Why cytosol?

Why is the malate-aspartate and the glycerol-3-phosphate shuttles located in the cytosol and intermembrane space? The krebs cycle happens in the matrix so why wouldn't they push electrons from the ...
4
votes
0answers
38 views

Cholesterol's role in lipid uptake [closed]

I'm studying the digestion of fats and I understand that our dietary fats mostly consist of triglycerides. We absorb the fats and eventually they end up in a muscle/adipose cell for storage (as ...
15
votes
1answer
123 views

Why does mint oil feel cold on the skin?

When putting (japanese) mintoil on the skin it produces a cool feeling. You can experience this, when adding it to your bath or using a spray with mint oil on your skin. The cool feeling occures ...
5
votes
1answer
201 views

What is the maximum number of babies a human woman can have?

I know you could divide the female fertility period (~40 years, right?) by 9 months which would give something like ~50 kids (with no multiple kids per pregnancy). The limiting factor in this ...
3
votes
2answers
76 views

Myopia as a microscopic superpower?

A few years back my Physics professor made a joke that his myopia (i.e., nearsightedness) gave him a "superpower" that allowed him to see close objects much more clearly than someone with typical ...
9
votes
1answer
121 views

Circadian Clock During a Flight

I am interested to know how does our Circadian Clock respond (and its resultant changes if any) when we are traveling across Time Zones? UPDATE 24th April I am reopening this question as the ...
3
votes
1answer
128 views

Can Leptospirosis be spread through human urine

I am wondering if Leptospirosis can be spread via the urine of an infected human individual. All of the sources I have been able to find on the web have stated that the disease is primarily spread ...
0
votes
2answers
78 views

Difficulties understanding a pathway [closed]

I am not a biologist and I would love to understand what is going on with this pathway. I went to the description but it's still complicated, and I couldn't follow. Can someone please help me with it? ...
1
vote
1answer
39 views

Pasteurization and Bioavailability of Antioxidants in Beet Juice

What are the effects of pasteurization on the antioxidants found in beet juice ? Does the process render most of the beneficial nutrients (betaine) useless and make them unable for the body to process ...
3
votes
1answer
74 views

What is the impact of stress on the human body?

Can stress trigger any changes in the human body? I'd like to know more about things less commonly known than, for example: sweating and tiredness. What are the long term risks of chronic stress? Do ...
7
votes
2answers
140 views

Is it possible for a human to wake up in a wrong way?

There's an old folk saying that goes like "He got out of bed on a wrong foot" - to indicate that the person's day is going poorly because of the way that person woke up. Is it is possible for a human ...
0
votes
1answer
45 views

What would happen if we had a device that produced oxygen inside of our lungs? [closed]

Hypothetically speaking, suppose there is a device that produces a limitless supply of oxygen. The device is inhaled by a human and is resting inside the (a) lung. What would hypothetically happen if ...
8
votes
2answers
148 views

Should we induce fever to assist healing?

I am currently reading "The Fundamentals of Anatomy Physiology" 10th edition, and have found it an incredibly interesting book. I have just been reading about the lymphatic system, and the various ...
1
vote
2answers
101 views

How does the body respond to blood donation; are there any possible risks?

Can blood donation cause any harm to the donor? I have been told so, but cannot find any references supporting this claim. I have also learned that our body will replace the lost fluids within 24 ...
3
votes
1answer
497 views

Possible genotypes for blood types?

If I am blood type B, what are all the possible genotypes that could be expressed by my parents? I think it might be 16 but I was reading online and saw this: Similarly, someone who is blood type ...
2
votes
1answer
209 views

When contracting a muscle will the muscle spindle stretch or contract?

When you contract your muscle, will your muscle spindle stretch or contract? And why? I was always under the impression that it was contracting your muscle spindle, but now I am not sure.
7
votes
2answers
159 views

Are unilaterally deaf people able to determine where sound comes from?

My question is on people deafened in one ear, but normal hearing in the other. Time and level differences between the two ears are only part of how the human body can localize the source of the ...
6
votes
2answers
59 views

What level of cellular radiation is harmful for humans?

What level of radiation at the frequencies used by the cellular network(1-2 Ghz) is harmful for human health?
5
votes
1answer
42 views

Stretching and compressing bones

The Young's modulus of elasticity when a bone is stretched is : 16×109 and when it is compressed, it is 9×109 N/m2. That means, change in length will be more if you compress a bone as compared to ...
4
votes
1answer
47 views

By what mechanism does Risperidone swell breast tissue?

There has been much talk of the anti-psychotic drug Rispeirdone causing un-natural breast tissue growth as well as galactorhea (milk production). Especially in young men and boys. What is the ...
3
votes
1answer
98 views

What causes the line patterns in the palm of the hand?

The line patterns on the hand are unique to each individual, but what causes these lines and re they advantageous in anyway?
2
votes
1answer
46 views

Atelectasis due to decreased surfactant in lungs

Surfactant is a protein lipid mixture produced by alveolar pneumocytes composed of Dipalmitoyl Phosphatidyl Choline lipid, apoproteins and calcium ions. This surface lines the alveolar epithelium ...
1
vote
1answer
27 views

What are the roles of cadherins in epithelial mesenchymal transitions? [closed]

I know that cadherins control the expression of cancer cells involved in the epithelial-mesenchymal transitions, but I was wondering exactly how the process worked.
4
votes
1answer
248 views

What do trans-fats do when in human body?

Trans fats cause health problems, especially to the heart. https://en.wikipedia.org/wiki/Trans_fat#Health_risks My guess is that all effects happen because trans-fats are inherently toxic as the ...
4
votes
1answer
377 views

What is our skin made up of?

Again, it is a basic question. What is our skin made up of? is it made up of many cells arranged in a systematic way or is it just like any layer say of a book?? what is the difference? where is the ...