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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Breathing becomes harder in certain wind conditions

I'm not sure if this is the right site to ask this, but it seemed like the best option. I've observed on myself that, if I stand on a train platform and a cargo train drives by, creating strong, ...
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1answer
75 views

Why does a Urinary Tract Infection cause a strong, persistent urge to urinate?

There are plenty of articles on the fact the a urinary tract infection (UTI) causes frequent and urgent urination. For example; on this National Institutes of Health webpage. My question is: Why ...
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1answer
192 views

How may the age of a child be estimated when required to do so, in video-graphic evidence?

How may it be possible to roughly conclude that a subject in a select piece of video-graphic evidence presented, is in fact a child, i.e. without the subject being, physically examined? Is it ...
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1answer
72 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
129 views

Why do you retch when you see something disgusting?

Why do you retch when you see something disgusting? I imagine it is some sort of evolutionary response, although I can't see the connection between receiving a signal that unhealthy conditions are in ...
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0answers
30 views

Can we predict a person's tolerance to cold exposure during excercise?

Being an amateur athlete and student of anatomy I've always wanted to know if there is a formula for determining an unconditioned body's tolerance to cold temperatures while exercising. I know the ...
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1answer
83 views

Which part of the reflex arc takes the longest time?

If the reflex arc is composed of 4 parts: Activation of sensory receptors, Conduction to and from the CNS, Transmission across the neuromuscular junction & Activation of the muscular contractile ...
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1answer
61 views

How body loses more fat in CO2 form than in sweating form? [closed]

Yesterday, I saw TV Game Show. There is question like this: Body loses more fat in which form? It gave 4 options: 1) CO2 2) sweating 3) xxx 4) xyz sorry i didn't remember 3 & 4 options. ...
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2answers
138 views

Can an argument be made that humans are 90% bacterial?

On the blog, All about Scientist in Microword: Microbiology, I read the post We are 90% bacteria, actually, which says that humans are 90% bacterial cells. If this is the case, then why don't we ...
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1answer
139 views

Colorblindness in females and random X chromosome inactivation

From Annenberg Learner: Because the X is inactivated randomly in cells, one cell could have the maternal X inactivated, while the adjacent cell could have the paternal X inactivated. This causes ...
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1answer
53 views

When does lactation occur?

High levels of estrogens and progesterone antagonize prolactin’s effect on the mammary glands, and it’s only after the placenta has been removed and the levels of estrogens and progesterone has ...
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2answers
127 views

Do intestinal flora have the same DNA as their host?

Please bear with me, this is not my professional field and I might be mixing things up. In an explanation why seeds won't start growing in one's intestines, the explanation given was that foreign ...
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1answer
64 views

Do vitamins protect you from common cold? [closed]

Do vitamins (taken as pills) boost your immune system, and make you less likely to contract diseases such as common cold or flu?
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1answer
333 views

Are there human-ingestible liquids that do not contain water?

My son asked me a question that stumped me: Is there anything a human can drink that does not contain water? It stemmed from a conversation in beverages in general where I was pointing out that they ...
3
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1answer
273 views

Why do humans masturbate? [closed]

Why does masturbating seem to be like an addiction? What controls or initiates the urge to masturbate? Is it good or bad or both and why is it so? I have heard guys who say that the do it ...
6
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1answer
979 views

Why does a fetus drinks and urinates into the amniotic fluid?

I was reading this website saying that fetuses urinate into the amniotic fluid. It also mentioned that, because we drink the amniotic fluid, we’ve been drinking our urine for months. However, why do ...
3
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1answer
75 views

Corpus luteum during the luteal phase and gonadotropins

Does the corpus luteum operate independently of the hypothalamic-hypophyseal-ovarian axis? I know that hCG sustains the corpus luteum in the absence of FSH and LH, but in an ovarian cycle where there ...
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0answers
72 views

Why does it take many sperm for one sperm to fertilize an egg?

Hundreds of acrosomes must undergo exocytosis to digest holes in the zona pellucida. This is one case that does not bear out the adage, “The early bird catches the worm.” A sperm that comes along ...
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1answer
79 views

Acrosomal enzymes and the female reproductive tract

My textbook wrote that the reason why acrosomal enzymes are so securely contained within the sperm (thus needing capacitation to facilitate their release) is to prevent any premature release in the ...
2
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1answer
113 views

How does the pancreatic beta-cell know how much insulin to secrete in response to glucose?

How do $\ce\beta$-cells know how much glucose is in the blood? I know that when glucose enters a beta cell it triggers the cell to produce insulin. $\ce\beta$-cells trap glucose by converting it into ...
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2answers
369 views

Why can't our eyes smoothly transition from side to side without focusing on a moving object?

Why are we not able to slowly and smoothly look from side to side, or up and down in a single and smooth transition, given that we are able to do this if our eyes are focused on a moving object?
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60 views

Why exactly does a scarf help against a neck pain and a sore throat?

I was going out without a scarf and as this day my neck was more sensitive; after a while my voice was rasping, I needed to cough and my neck was hurting slightly. After coming home I put on my silk ...
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1answer
208 views

Why are plants classified in living things? [closed]

@Volunteers Beware that I am none of the biological magnates. Nor a philosopher. This is just a sign of curiosity. And, I want only an intuition that enables me to see the difference. As far as I ...
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1answer
43 views

How DNA programs the first cell in womb into a human [closed]

Sorry if you see me silly. I am just a programmer happens to be curious about biology... So far I understand how DNA make protein, how cell divides, how one composed of cells->tissues-> organs. But,...
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42 views

Why does histamine release in Type I hypersensitivity help in case of parasites?

The IgE system exists because the same events which lead to often-life threatening complications of allergy, in presence of parasites are helpful in their elimination. The tissue injury mediated ...
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24 views

Pathogenesis of type IV hypersensitivity

In hypersensitivity, as I understand it, a normal immune response gets excessive, misdirected or wrongly regulated to cause tissue injury. The various types determine the various ways in which the ...
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16 views

Where can I find epigenetics related microarray dataset for Alzheimer and Parkinson diseases?

In my thesis project, one of the tasks regards co-expression network analysis for epigenetics (methylation) data. In GEO and Array Express repositories, I have already searched for the microarray ...
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1answer
82 views

After doing brush I feel hungry? [closed]

Why I feel hungry after brushing my teeth in morning? I usually have my dinner in between 9 to 10 at night and then I sleep at 12. Sometimes I wake up at 6 in morning and then I go to brush my teeth. ...
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1answer
36 views

How are cardiac cells stimulated by an action potential?

Why, and how, does the action potential of one cell in the heart stimulate an action potential in the next cell? I'm interested in an answer with citation.
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39 views

Why are kidney discard rates so high?

A recent report from UNOS states: The kidney discard rate has returned to pre-KAS levels, dropping from 20.2 percent in the first six months to 18.4 percent in months 7-10. To me, this seems ...
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2answers
110 views

Blood draw from the elderly or those with tiny veins

A lot of people have very small veins making it next to impossible to draw blood. Would a nitroglycerin tablet (or some other vasodilator) before drawing blood help to enlarge veins?
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1answer
32 views

How does increased heat increase the rate of metabolism?

I have heard that taking a hot shower helps blood circulation metabolism. For (2) metabolism, I think that the rate is increased since kinetic energy is given to compound to bond with enzymes ...
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0answers
19 views

What are necessary parameters for a tissue scaffold to be biodegradable?`

I am a mechanical engineer with little biological experience, but I have recently been looking at tissue scaffoldings. My current understanding is as follows, but may be flawed. I would appreciate ...
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28 views

Why doesn't EMG data for triceps show a clear relationship?

In a surface electromyography (EMG) experiment of the triceps muscle where a person lifts weights, I found the value for maximum amplitude of EMG signal to be rather similar for all loads of 0-10kg. ...
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2answers
69 views

What neurons make up the CNS?

I generally see it written that there are three types of neurons, classified by projection: (1) sensory neurons, (2) interneurons, and (3) motor neurons. Now, in the CNS, I don’t think there would be ...
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16 views

What will happen if an anaplastic/cancer cell is used in cloning?

Since anaplastic cells have high glycolytic ratio and replicative potential, if they are used as the somatic cell in a model of cloning(like dolly's mother's udder cell), what is likely to happen?
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3answers
237 views

Can/Have cancer cells be/been used in stem cell culture lines?

Since Cancer cells have unlimited growth potential, can they be induced towards totipotency and pluripotency? If so, can cancer cells be used in stem cell culture because of similar properties of ...
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1answer
113 views

What's the difference between tumor cells and host cells? [closed]

When you talk about cancer, is there a difference between tumor cells and host cells ? What is the role of immune cells ? in a nutshell ?
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3answers
115 views

Are missing limbs hereditary?

So with my basic understanding of biology, DNA can change over time. Does this mean that if one (or both) parents have something major missing (like a limb), the kid will come out without a limb? ...
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0answers
119 views

Why did humans evolve the ability to feel such a high level of heat pain? [closed]

It's probably because our ancestors were frequently around 300°C metal which badly damages flesh in a fraction of a second because they made fires to cook. I don't see why that would cause natural ...
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1answer
364 views

What is the normal blood water content

What is the normal water volume per 1 L of blood, and how much deviation from that norm causes dehydration or hyponatremia?
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1answer
176 views

Why would glucocorticoids promote glycogenesis and not glycogenolysis?

I read in a textbook that glucocorticoids can stimulate the synthesis of glycogen. I do not understand this at all—shouldn’t glucocorticoids try to increase the blood level of glucose? Why would they ...
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0answers
41 views

Why do workouts cause your muscles to feel heavy?

I know that muscle activity causes your muscles to build up lactic acid. Is this the specific reason that your muscles begin to feel heavy? How does this relate to the healing or inflammation process ...
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27 views

Is there any evidence to suggest that exercise reduces the side effects of caffeine?

I heard a friend say: I'm not drinking coffee this week. My body can only process the caffeine if I run at least 15km a week. I found this claim fascinating - that exercise temporarily ...
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1answer
223 views

Are human teeth only diphyodont or both diphyodont and monodont?

Many books say human teeth are only diphyodont .But premolars appear only once and one molar appears later which should be considered monophyodont. Dental Formulae : CHILD - 1. Incissor -2/2 2. ...
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2answers
257 views

Does soap kill human cells?

I see many products, particularly hand soap and cleaning products, that claim to kill 99.9% or more of bacteria. This makes me wonder, if the chemicals are potent enough to break down bacterial cell ...
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1answer
81 views

When you blow through your nose while holding it closed to “depop” you ears, why do you sometimes feel it in your eyes?

After your ears have "popped", for example on a flight, I heard you are supposed to hold your nostrils closed and blow through your nose to readjust the pressure to the normal level. Why do you ...
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1answer
130 views

If all bacteria in human gut are dead, can they be there again?

If someone likes to eat chocolate, she may have gut bacteria which like chocolate according to some articles that I have read. http://www.theatlantic.com/health/archive/2014/08/your-gut-bacteria-want-...
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1answer
69 views

Movement of sperm to the egg

Sperm swims through semen and reaches the haploid egg in the oviduct during fertilisation. Once the sperm reaches the cervix, through what does the sperm swim through to reach the egg? Is the ...
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1answer
78 views

How can a blood test give information about rickets?

Can we detect rickets from a blood test? What evidence pf rickets is in the blood and how is the blood treated to detect rickets?