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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2
votes
1answer
20 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
0answers
13 views

Why do fingers/finger tips swell during winters?

Why do fingers/finger tips swell during winters (of temperature 5-15 degree celsius)? During winters mine and many others's fingers swell. is it due to blood circulation or what?
3
votes
1answer
47 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?
0
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0answers
22 views

Why do fingers swell during winters? [on hold]

Why do fingers swell during winters (of temperature 5-15 degree celsius)? During winters mine and many others's fingers swell. is it due to blood circulation or what?
9
votes
1answer
118 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 ...
0
votes
0answers
27 views

The future of human evolution [on hold]

While in college I read a book that said human have stopped evolving internally, but rather we now evolve externally in the form of technology, ie instead of growing claws we make a knife. Is this ...
2
votes
1answer
26 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
31 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 ...
8
votes
1answer
630 views

What causes knuckle “popping” and the feeling of relief that comes from it?

Many people like cracking their knuckles. I have always been curious about it. What happens when we crack knuckles? What creates the POP sound? Why do we get a relief-like feeling after doing it?
4
votes
0answers
37 views

Why do we get tired

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
44 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 ...
-1
votes
0answers
28 views

Increasing height after 21 years [closed]

I am 21 years old guy and my height is only 5.4". Both my parents are short heighted. My family is also short heighted but my mom's family have a preety fair height. I have a younger brother and he is ...
2
votes
0answers
23 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?
3
votes
1answer
99 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?
7
votes
2answers
4k views

How does HCl not burn our stomach?

How does the digestive acid (HCl) not burn the surrounding skin of our stomach? It digests the majority of raw food we eat but how does it stay safely in our stomach? Also, how does the stomach ...
15
votes
6answers
2k views

Human evolution: Where *exactly* did the first human come from, whose parents were not?

Layman here. So I have never really quite understood this facet of human evolution, (or any other for that matter), in that, I understand the evolutionary process, but I get lost on the 'border' ...
4
votes
1answer
90 views

Length of sleep time

Why do we wake up after 6-8 hours of sleep ? Why don't we sleep for lets say 20-30 hours ? What mechanism is it that controls when to wake us up and how does it determine the moment that we should ...
4
votes
2answers
518 views

Why do men have a higher hematocrit (red blood cell count) than women?

The hematocrit, also known as packed cell volume (PCV) or erythrocyte volume fraction (EVF), is the volume percentage (%) of red blood cells in blood. It is normally 45% for men and 40% for women. ...
6
votes
1answer
70 views

Time lapse between fresh blood's exposure to air and that same blood turning darker red-brown

For investigative purposes, I'm searching for a tool that can be used as a quick visual assessment of the the length of time that blood has been exposed to air after the blood flow has stopped.. Let's ...
4
votes
0answers
21 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 ...
13
votes
3answers
3k views

Supercomputer Vs Human Brain

With supercomputers doing calculation in petaflops ($10^{15}$ Calculations per Second), have we crossed the speed of Human Brain?
0
votes
1answer
89 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 ...
0
votes
1answer
36 views

Survival with only water but no food [duplicate]

How long can the average, healthy adult human survive with only water?
1
vote
2answers
30 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 ...
7
votes
1answer
329 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 ...
7
votes
4answers
190 views

How does an embryo know where to grow limbs etc

For example you have a cell or already a bunch of cells. Those cell(s) divide and after several week you have a grown organism, for example a human with limbs, several different organs etc. However, ...
4
votes
1answer
36 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 ...
3
votes
1answer
552 views

What is the minimum air pressure the human body can tolerate if oxygen supply is not an issue?

Disregarding hypoxia, what is the minimum air pressure that the human body can tolerate? (i.e. at what air pressure would the blood start to boil, or skin start to burst, or whatever else might ...
10
votes
2answers
188 views

Why do we urinate more when we are nervous?

This question is a result of my personal experience... But I guess that is common for many of us. My school timing is 8:00 am to 1:30 pm (usually). During normal school days I typically urinate one ...
0
votes
1answer
17 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.
2
votes
1answer
878 views

Why does ear wax taste sour?

Why does ear wax taste sour? I am interested in both the physiochemical mechanisms and the evolutionary reasons behind the sour taste of earwax.
9
votes
1answer
272 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 ...
2
votes
1answer
29 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 ...
1
vote
1answer
37 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
25 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
26 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 ...
2
votes
1answer
33 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 ...
2
votes
0answers
19 views

Cholesterol's role in lipid uptake

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 ...
5
votes
1answer
142 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 ...
4
votes
1answer
50 views

What happens when someone is stung by a jellyfish?

What happens in the human body when someone is stung by a jellyfish; namely a box jelly. Judging by what I have heard about the stings I'm guessing that they involve a neurotoxin. But what is ...
1
vote
1answer
31 views

Myopia as a microscopic superpower?

A few years back my Physics professor made a joke that his Myopia/Nearsightedness gave him a "superpower" that allowed him to see close objects much more clearly than someone with typical eyesight. ...
7
votes
2answers
119 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 ...
3
votes
1answer
102 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 ...
4
votes
1answer
2k 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?
0
votes
2answers
73 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? ...
20
votes
4answers
2k views

How and where, in the human brain, are memories stored?

Background I am a computer programmer who is fascinated by artificial intelligence and artificial neural networks, and I am becoming more curious about how biological neural networks work. Context ...
3
votes
1answer
60 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 ...
1
vote
1answer
21 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 ...
8
votes
2answers
126 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 ...
9
votes
3answers
4k views

Why can all animals swim in water without learning to swim but humans cannot?

I had a question since I was a child. I was always curious about the fact that all animals can swim in water. They don't need any training or to learn swimming. But humans need to learn to swim. Why ? ...