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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3
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1answer
69 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 ...
1
vote
0answers
46 views

Which sperm fertilizes the 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 ...
0
votes
1answer
71 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
votes
1answer
107 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 ...
6
votes
2answers
344 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?
0
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0answers
54 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 ...
-5
votes
1answer
173 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 ...
0
votes
1answer
39 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. ...
0
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0answers
40 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 ...
0
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0answers
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 ...
0
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0answers
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 ...
-2
votes
1answer
74 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. ...
2
votes
1answer
34 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.
3
votes
0answers
38 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 ...
2
votes
2answers
98 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?
1
vote
1answer
30 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 ...
3
votes
0answers
18 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 ...
0
votes
0answers
27 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. ...
3
votes
2answers
53 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 ...
0
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0answers
15 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?
3
votes
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 ...
0
votes
1answer
104 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 ?
1
vote
3answers
109 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? ...
2
votes
0answers
113 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 ...
0
votes
1answer
276 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?
2
votes
1answer
136 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 ...
2
votes
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 ...
0
votes
0answers
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 ...
0
votes
1answer
192 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. ...
6
votes
2answers
246 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 ...
1
vote
1answer
75 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 ...
1
vote
1answer
121 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. ...
1
vote
1answer
63 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 ...
1
vote
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?
3
votes
1answer
47 views

Why would growth hormone (somatotropin) cause both lipid AND glucose release?

GH increases lipolysis (lipid breakdown) and the release of fatty acids from adipocytes into the blood. Fatty acids then can be used as energy sources to drive chemical reactions, including ...
2
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0answers
74 views

Proteases in the blood

I’m reading on hormones and the book talks about how peptide or amine hormones are easily broken down by proteases present in the blood plasma. This has led me to question the interactions between ...
0
votes
1answer
107 views

Why are lipid-soluble substances harder to excrete?

I understand why water-soluble substances can be excreted. However, why are they easier to excrete than lipid-soluble substances? Why can’t lipid-soluble substance be excreted just as easily in the ...
2
votes
1answer
134 views

Why is chromatin not condensed during interphase but is in prophase [closed]

Cell cycle goes through three processes: Interphase Mitosis Cytokinesis Why are chromatins not condensed during interphase but instead condensed at prophase of mitosis? What makes them condense ...
2
votes
1answer
149 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 ...
2
votes
2answers
160 views

Why is warm water comfortable, but warm air uncomfortable?

I friend of mine tried floating, where you lay in a bath kept at body temperature (98.6 degrees F). He said after a while you don't feel the water at all. This made me wonder why being in warm water ...
11
votes
2answers
676 views

Is global life expectancy normally distributed?

I am trying to find out what the world distribution of life expectancy looks like.
2
votes
1answer
36 views

What is the mechanism of folic acid deficiency and neural tube defects?

I am having difficulty finding the mechanism by which folic acid reduces the risk of neural tube defects. I know that it does so, but what in particular actually occurs with folic acid deficiency to ...
0
votes
1answer
20 views

Absorption of Topical Magnesium

Can Magnesium be absorbed through the skin? Some athletes believe that Homeopathic magnesium lotions can reduce muscle pain. I've tried this and it doesn't work nor can I see how it can.
3
votes
1answer
113 views

Why is one testicle larger than the other?

Why is one testicle generally larger in humans? Just due to asymmetric development, or is there a hypothesis as to some utility it serves? I read that the different heights may be attributed to ...
2
votes
3answers
79 views

Do adult humans exchange beneficial bacteria? If so, how?

Recently there has been increasing interest and research into symbiotic bacteria present in humans and human gut. I'm aware of two new discoveries: humans are surrounded by a unique cloud of ...
2
votes
1answer
29 views

Can specific B-cells be created in a lab? [closed]

Instead of creating protein sequences, could that stepped be skipped and just have B-cells created to manufacture a particular type of immunity?
0
votes
2answers
65 views

When did human ancestors learn to walk? [closed]

Where does our ancestor learn to walk from? How do we control our legs whenever we take a step? I confuse every time whenever I take one step.
4
votes
1answer
90 views

Is it easy to test human Flicker Fusion Threshold?

How would you go about testing human flicker fusion threshold? Is the testable rate consistent in humans over time or volatile?
3
votes
0answers
36 views

Can body temperature affect the quality of sleep?

If so, how does it influence our sleep? And what can we do to improve the quality of sleep by adjesting our body tempurature?
1
vote
0answers
26 views

What are the molecular/cellular basis of pruritus ?

Could someone please explain the cells and molecules involved in the clinical phenomenon of pruritus ? I'm interested in a general view about the subject, but detailed answers will be appreciated. ...