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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What are differences between formation of embryonic disc in chick and mammal embryo?

Exam question which got lowest average points in my university: 1/5 average. No markscheme available so my attempt below. I assume that embryonic disk prefers to germ disk such that Formation prefers ...
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1answer
34 views

What are studies linking dietary choices over life with probability of reaching higher ages? [closed]

Are there big studies that link diet and lifestyle choices with the probability of reaching a certain age? What are their conclusions?
4
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1answer
99 views

Do the eyes play any role in producing the visual experiences you have during dreaming?

Sometimes, you remember a vivid picture of a dream that you saw. What is the role of your eye in this experience? Please provide me with the answer that is as simple as possible since I am in Class ...
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0answers
13 views

Would constant light or fading light be registered as more wakefulness promoting by the Supra Chiasmatic Nucleus?

During the fall and winter season, a number of people are experiencing Seasonal Affective Disorder. One of the way it has traditionally been treated is with a dedicated lightbox - a very high ...
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0answers
13 views

Dawn simulation - does color change affect waking up?

just curious. Are there any works or research results related to the influence of light color used for dawn simulation? I mean those wake-up lights which try to simulate dawn to make waking up better ...
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0answers
42 views

What factors affect the likelihood of auditory stimuli causing arousal during sleep?

I've noticed that the sound of water drops makes me wake up from sleep but other more strong sounds don't make me wake up. I can't find anything about this. The only reason I can think of is maybe ...
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0answers
16 views

Physiological function of CFTR gene product? [duplicate]

I just need a clarification. If I am to talk about the physiological function of the CFTR gene product? Then what should I do research and talk about? The only physiological function that I can ...
5
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1answer
651 views

Are there any effects of elevated Cysteine levels on cognitive function?

I'm looking at this diagram of homocysteine metabolism and see two distinct pathways that the amino acid may get metabolized to: with vitamin B12 it gets converted back into methionine, while with B6 ...
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3answers
2k views

Where does the 'C' in exhaled CO₂ mostly come from?

When a human being exhales CO₂, what is, by the numbers, the main source of carbon atoms exiting the body in this way? I mean what class of cells, or which tissues are the biggest on a pie chart of ...
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2answers
812 views

Ill effects of urea and NH₃ on metabolism

What exactly does urea do that harms our body? Does it interfere with our cellular processes or disturbs the colloidal onchotic pressure of our blood? I have heard that NH3 damages the brain. What ...
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0answers
47 views

Does eating antacid (such as Magnesia) before meal have any impact on digestion? [closed]

During an anatomy lecture I heard of the importance of the acidity of gastric acid (e.g., killing microorganisms, dissolving food, being a factor for triggering further processes). If a healthy person ...
7
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1answer
136 views

How fast can a human run?

I'm a runner (cross country) and I'm always amazed at how fast Olympic sprinters are. There's a lot of hype about those in the 100-meter dash being the fastest in the world, and we're constantly ...
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2answers
197 views

The gender of offspring of Twins?

Given identical twin males, Michael and Douglas, Douglas and his wife have four children, all of whom are girls. Michael and his wife have only one child, a boy, and are expecting another. What are ...
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3answers
738 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 ...
0
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1answer
27 views

Recovery from a more severe injury can be shorter than from a less severe one [closed]

I vaguely remember reading somewhere that in certain cases, recovery from a more severe injury can occur faster than from a less severe injury. This was motivated by claiming that the less severe ...
2
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3answers
72 views

Is the quality of sleep dependent on sleep duration?

I've been facing this lately, where I will wake up in the middle of the night after sleeping for perhaps 2-3 hours and be wide awake, but when I go back to sleep, I wake up more tired than before. ...
8
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1answer
78 views

Can a human cell live indefinetely in a controlled environment?

How long can a human cell live in a controlled environment, given all necessary nutrients, temperatures, mechanisms for waste removal, and other requirements are provided for? Put differently: Can a ...
3
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1answer
24 views

How is Microenvironment strictly defined?

I started to think this definition of Wikipedia: Microenvironment (biology), a small or relatively small usually distinctly specialized and effectively isolated biophysical environment (as of ...
4
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1answer
74 views

Are all functions of a human cell known? [closed]

Please bear with me as I'm intruding into your world from a computer science background. In programming, once you have created a program, you know all functions of that program. Thus, 100% knowledge ...
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2answers
57 views

Can Hepatitis be caused by Bacteria?

There are many information about viral hepatitis. But it is interesting for me, can bacteria cause the hepatitis too?
3
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1answer
118 views

Do you produce more sperm after 1 week of abstinence vs 1 year of abstinence

Question: I was wondering if the amount of sperm increase with the amount of abstinence? Side questions: Is their a max amount of sperm? What happens with the excess amount?
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2answers
4k views

Why is cold water more refreshing than warm water?

Obviously, the temperature of water does not affect its chemical composition. At least not in the ranges we are likely to drink it in. Yet it is clearly far more pleasant and refreshing to drink cool ...
0
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1answer
45 views

Is there any research paper which identifies left and right brained behavior?

There are many web puzzle to identify, but does it really have any scientific proof? something like - http://braintest.sommer-sommer.com/en/ any logic behind it?
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2answers
9k views

What could cause hairs to gray at the tips but not the roots?

I have noticed that some of my sporadic gray hairs are gray at the tip side but oddly, not near the roots. Some are even only gray in the middle. I find all of this very counter intuitive, and I ...
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1answer
53 views

Is the activity of enzymes in the human body affected by the outer temperature?

I have to do a research about the enzymes in the human body and the things that affect them. I know that the body temperature affects the activity of enzyemes but I'd like to know if the outer ...
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1answer
17 views

Help me understand my membrane potential assignment

Epithelial with the ability to transport NaCl is bathed in an isotonic salt solution with these values (in mM): 136 Na, 6 K, 140 Cl. The intracellular concentrations are: 45 Na, 100 K, 13 Cl. The ...
3
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1answer
640 views
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2answers
1k views

Why do we like salt?

A few friends of mine told me that salt provides zero nutritional value to us, and in fact can harm our bodies. Now, these guys are medical students, and being an engineering student myself, I decided ...
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3answers
4k views

Why isn't vomit corrosive?

Vomit comes from gastric acid, right? And in gastric acid there is HCl and HCl is corrosive (strong), how come when I vomit, it doesn't destroy things that it (as the vomit) hits (such as floor, ...
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2answers
51 views

Problems understanding membrane potential

I understand that membrane potential is the difference of the extracellular and intracellular ionic charges, due to their concentrations. We say that the extracellular space has a charge of 0 and then ...
8
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1answer
238 views

How do the pharmacodynamics of the NSAIDs differ and are there “resistant” COX phenotypes?

I know that the non-steroidal anti-inflammatory drugs (e.g., aspirin, ibuprofen, naproxen) affect the enzymes cyclooxygenase (types I and II). Is there any difference in the degree to which these ...
2
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1answer
583 views

Are Asian people shorter than Europeans?

People in different countries have different average heights. For example, Wikipedia's article on human height states that Australian men have an average height of 177.8 cm, and Australian women 163.8 ...
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1answer
41 views

Understanding intra and extracelullar concentrations (membrane potential)

I have 4 question (not homework) What happens to the cells membrane potential if: a) Na+ outside rises by 40mM b) K+ inside rises by 10mM c) K+ outside rises by 10mM d) A- (impermeable ion) ...
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0answers
40 views

Are some facial features more important than others in human facial recognition?

I'm often surprised by the human ability to correctly identify other individuals despite significant modifications due to ageing, hairstyle, injury etc. But, sometimes the addition of a beard and a ...
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1answer
40 views

Why can't we smell our own bad breath? [closed]

Why can't we smell our own bad breath. Is there any way we can do that?
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1answer
30 views

How can ingesting a prion “infect” someone?

That's something that's been bugging me for a while... Our gastrointestinal tract produces proteases that degrade proteins. Prions are proteins. Shouldn't they be broken by proteases? Also, how can ...
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0answers
28 views

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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0answers
34 views

Can sealed epiphyseal growth plates theoretically be restored via epigenetic or genetic methods?

I know that epiphyseal growth plates seal up once people become young adults and that it is currently impossible to restore them to actively produce new bone growth but, is it theoretically possible ...
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0answers
29 views

Is Canine teeth enough evidence to prove that one is a Carnivore?

This question does not assume that we are meant to be carnivores in the first place; In fact I have no idea to which category we belong to anyway! There are several posts online indicating that ...
0
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1answer
36 views

Is the innate immune system capable of identifying all foreign antigens?

I've been studying immunology on my own lately and I would like to know if the macrophages and the other components of the innate immune system are capable of identifying all foreign antigens. As far ...
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3answers
139 views

Why can't you just take a vitamin? Why you need a healthy diet on top of that?

From what I understand, your body needs certain amounts of vitamins and minerals to maintain health. Why can't we just take enough pills to obtain these vitamins and minerals?
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0answers
30 views

Do animals have social status as humans in our society?

As our society and it's functioning is closely related to the ones of animals, one question arises: Do animals in nature have social status as humans? People often display it publicly, by buying nice ...
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1answer
32 views

Help me understand how the thyroid secretes

Please have a look at this close up light microscopic image of a thyroid gland: So I'm guessing the cubic epithelial cells surrounding this big red pulp are the secreting cells...? If so, is the ...
3
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1answer
81 views

How does electrolarynx work?

I have heard that this is an effective replacement for patients who have a dysfunctional larynx, partly due to cancer. I am curious to know the inner working of this device and why such a robotic ...
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2answers
378 views

In humans what is the last metabolic process to cease after death?

After death which of our body's metabolic processes will continue functioning for the longest?
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0answers
57 views

Do humans have chemosensors for nutrients or chemicals?

I'm reading about chemoreceptors on Wikipedia, and see that the typical ones are mentioned: taste, smell, CO₂. I would like to learn more about the other kinds of chemoreceptors that humans may ...
5
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1answer
552 views

Total amount of CO₂ / Oxygen in Bloodstream in Humans

How much carbon dioxide and oxygen from/for respiration are in the bloodstream at any one time? (mass per litre of blood or similar) And would there be much more aside from the blood in tissue, e.g. ...
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2answers
1k views

How do we know the presence of light when our eyes are closed?

Last night I laid on my bed and tried to go to sleep with the light off. I closed my eyes (but hadn't gone to sleep). My younger brother touched the wireless mouse (which had laser) for the laptop. ...
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0answers
73 views

How many proteins are synthesized in human body throughout life?

My idea to calculate this is: Define up to what age will do the calculation. (for instance 60) Determine how many cells born and died up to that point in life. (by type of cell) Determine how many ...
13
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1answer
79 views

What is the mechanism responsible for the periodicity of hiccups?

Hiccups (singultus) are caused by involuntary spasm of the intercostal muscles and diaphragm, producing a sudden inspiration with associated glottic closure. It seems the neurobiology of the reflex ...