This tag is for questions about the general biological features of human beings (as opposed to the biology of non-humans).

learn more… | top users | synonyms

2
votes
2answers
367 views

Can I drink warm/hot tap water? [closed]

I live in Canada and tap water is drinkable, as a matter of fact, the government puts a little bit of flouride in the tap water so it cleans your teeth. My wife and mom always tells me not to drink ...
0
votes
0answers
49 views

Physiologically, how can stress/anxiety cause neuropathy?

According to the Mayo Clinic, stress/anxiety can cause "pins and needles" (neuropathy) sensations all over the body. But how can this be? My understanding of the sensory pathway is that sensory ...
1
vote
1answer
50 views

Can signals travel “backwards” in the sensory pathway?

My understanding of the "sensory pathway" is that its a linear, directional pipeline as follows: Nerves (fire various signals depending on the type of sensors they are) Fibers (transmit signals from ...
1
vote
0answers
25 views

Would blue light be effective to help average people when sunsets come much earlier in the day?

I know people with SAD (Seasonal Affective Disorder) benefit from blue light in the winter as night-time comes much earlier (in the UK, sunset is around 4pm in December, compared to 9pm in June). ...
7
votes
1answer
163 views

How are bones growing, if bones are not connected to the brain?

If the bones are not connected to the brain, how is their growth controlled? This question is not a duplicate of the question Mechanisms of bone growth, as this question deals with how bone growth is ...
9
votes
3answers
208 views

What causes feeling of feet falling asleep to be delayed?

This answer explains the sensation of extremities "falling asleep" as a result of sustained pressure on a nerve. The answer links to an external web page that says that the feeling "quickly goes away ...
3
votes
1answer
104 views

How are arms different than legs?

Ok, this is a bit of a tangent question, but it came up yesterday and I didn't know the answer: How are arms and legs defined physiologically? For example, we say humans have two arms and two legs, ...
0
votes
0answers
32 views

Maximum heart rate increase/decrease while physically active [duplicate]

I'm a computer scientist and implementing a heart-rate monitor for physical exercise. While I try to improve my code, I stumbled over the question how fast the heart rate can change within a given ...
7
votes
1answer
3k views

Why is fructose not glucose the main energy source of sperm?

The seminal fluid contains fructose as the main energy source for the sperm and not glucose. Why is fructose and not glucose the primary energy source for these sperm, since glucose is the ...
-1
votes
1answer
43 views

Effect of Western chicken and GH [closed]

I heard this clause from my teacher one week ago: Chicken are grown in half a year until eaten in Baltic countries - Estonia, Latvia and Lithuania, for instance, [probably in other parts of ...
4
votes
1answer
77 views

How can fresh cavities form at the margins of sliver amalgam fillings on teeth?

Silver amalgam fillings predominantly contain silver a known bactericidal agent and mercury which a known toxin and has bactericidal property. So how is it that the plaque bacteria survive near the ...
0
votes
1answer
88 views

Can swallowed fingermails, hair, or skin get caught in your appendix? [closed]

There is a common saying in my place: If you eat your skin, hair or nails, it will be deposited in the cecal (Vermiform) appendix, and can cause appendicitis. (This is mostly told to children to ...
7
votes
4answers
162 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, ...
3
votes
2answers
50 views

Hydrophobia Outside of Rabies?

RELATED: Why does rabies cause hydrophobia? Agony, Hydrophobia and viruses in the light of evolutionary principles Has hydrophobia been found outside of rabies? I have only seen it ...
0
votes
0answers
36 views

Cigarette consumption dose-response function WRT health outcomes

I'm curious how health risks (mortality, lifetime probability of cancer, etc) change with cigarette consumption. Specifically, treatring cigarette consumption like a continuous variable, rather than ...
0
votes
1answer
30 views

Deeper Learning in Physiology? [closed]

I am a Pharmacology and Toxicology major at a large state school. I was only required to take physics I and II. (algebra based) At first I thought that was fine, but I soon began to realize that I ...
7
votes
1answer
2k views

Can a human acquire a memory of an animal? [closed]

I would like to know if it's possible for a human to acquire an animal memory. I mean, animals store their memories in their brain, right? And so do we, humans, store our memory. So, is it possible ...
7
votes
1answer
168 views

How does the cornea breathe during sleep?

The cornea is not supplied with blood vessels and so exchanges gases directly with the atmosphere. So how does it breathe during sleep when our eyes are closed?
9
votes
3answers
553 views

Do memories have mass?

If it were possible to live forever, would our brains grow infinitely with the number of memories that we store? Or would we remove old memories as we create new ones?
3
votes
1answer
58 views

Effect of closed eyes on balance?

Suppose you want to stand on one leg. Doing it eyes open is not that difficult, but doing it eyes closed seems to be difficult. Why?
2
votes
1answer
47 views

Like size and colour constancy, why does the brain not maintain focus constancy?

I have progressive myopia. I grew up with perfectly normal eyes but slowly started getting myopic. The thing is, my brain knows (or should know) what the world looks like -- it knows that far away ...
2
votes
1answer
80 views

Why can't people talk while inhaling?

Why do we have to exhale in order to talk? From looking on Wikipedia, it seems like it has something to do with the glottis, but I'm not clear on the mechanism that makes speech sound so different ...
1
vote
1answer
35 views

Clonidine's adrenonergic nature?

I am little confused here. I used the term adrenoagonist and sympatholytic to describe the compound. However, my teacher says that the correct term here is adrenomimetic -term. My understanding of ...
1
vote
1answer
41 views

Anesthetics, specifically inhaled anesthetics

I have had a look at previous inhaled anesthetics and many of them appear to be fluorocarbons. What could be the mechanism behind fluorine's anesthetic properties? Is it the specific bonding pattern ...
4
votes
1answer
52 views

How to evolutionary explain menstrural cycles synchronization? [closed]

Sorry, I can not indicate the source, but I read that menstrual cycles of women who live in the same house over time sync. Is it true? How does it work?
12
votes
2answers
2k views

How was birth control realized in ancient days? [closed]

In ancient days, there were no birth control methods like condoms or contraceptive pills available. How did they control pregnancy?
3
votes
2answers
2k views

Presence of MHC on red blood cells

Do red blood cells have no MHC? (I have often heard that they do not.) If so why are they not destroyed by immune cells?
2
votes
3answers
154 views

Is there a stem cell/ biogel method exist for muscle and tendon lengthening?

Is there a stem cell/ biogel method exist for muscle and tendon lengthening? It is known that height surgery is limit to six inches with two surgeries and three inches each, it is also true that ...
3
votes
2answers
174 views

How does Humira work when injected into patients with rheumatoid arthritis?

OK, I have rheumatoid arthritis and I've been injecting Humira 2 times a month for the last 8 months. As far as I know rheumatoid arthritis is simply an immune system disorder which makes the immune ...
0
votes
1answer
18 views

How can Pyridostigmine have the indication of Myasthenia?

I am thinking how pyridostigmine can be used in the treatment of myasthenia gravis. Its similar compound (neostigmine) is also anticholine esterase. This compound has the indication of myasthenia ...
2
votes
1answer
101 views

Sodium levels and blood pressure

Why does low Na+ levels cause hypotension (low blood pressure). Alternatively, why does excessive intake of Na+ cause hypertension or high blood pressure? From what I understand, there are ...
0
votes
1answer
51 views

How does anger relate to blood pressure?

Anger is an emotion generated by neural processes in the brain and is associated with elevated blood pressure. How can an emotion, which is totally related to brain, result in blood pressure changes?
22
votes
2answers
9k views

What causes fingerprints to form and why is the pattern formed unique?

I've found research that suggests that the reason we develop fingerprints is because they aid us with feeling surfaces (Scheibert, et al. 2008) and not to increase friction and help with the gripping ...
-2
votes
1answer
46 views

To understand side-effects for nebivolol's beta1 selective pathway in PubChem? [closed]

Assume you have a drug nebivolol. When nebivolol is used as beta1 selective drug, beta2 is mostly for side effects, but this is not clear from PubChem. I do not know any cases where nebivolol is used ...
2
votes
1answer
47 views

How to manage fat-gluten oxidation in celiac disease?

Assume you have been in non-gluten diet 20 years. You built mass 8 mass with substances containing gluten (endogenous gluten stored in fat). Then, celiac disease is diagnosed. You have been 3 ...
3
votes
1answer
96 views

How common is complete heterochromia?

How common is complete heterochromia? (One iris is a different color from the other) Are there any statistics available for this? If no, why not?
3
votes
2answers
178 views

Why do humans have only two nipples?

If other animals have more than 2 nipples, then why do humans have only 2 nipples? Even my pet dog has more than 2 nipples.
0
votes
2answers
32 views

T-cells Question

T-cells are important for efficient vaccination since they have: A. T-cell receptor (TCR) B. CD4+ C. CD8+ D. Memory My gut is telling me it's A since the TCR would recognize the antigens but I ...
3
votes
1answer
317 views

After vasectomy, where does the sperm go?

After vasectomy, where does the sperm go? Vasectomy Procedure cuts only vas deferens, But Our Testes still produces sperm, if there is no output for sperm, where does it go?
4
votes
2answers
114 views

How do gory images lead to nausea?

How do gory images lead to nausea? Yesterday my friend visited shock sites (a website). He said that he got nauseous sensation within seconds after viewing the gory images. However, I don't ...
1
vote
1answer
104 views

Why the scent of mouth gets dirty after not eating for a long time?

After a long time of hard workout,not eating and nervousness makes your taste and scent of mouth very uncomfortable and bad why this happens and is there any way to prevent it?
5
votes
1answer
149 views

Why does hair thicken and become more rough after a razor shave but not after one using a trimmer? [closed]

If a razor cuts only the hair, then how does hair thicken and become more rough with a razor shave and not after one using a trimmer? If both are used for hair removal, why is there a difference in ...
8
votes
2answers
120 views

How Circumcision could reduce the chance for a HIV infection?

Circumcision removes the foreskin of the penis which mainly acts as a cover to the penis. Normally removing the foreskin makes more vulnerable to any STD, so how could circumcision reduce the risk of ...
0
votes
1answer
139 views

What is the exact chemical composition of human body? [duplicate]

I've just watched Breaking Bad Season 01 Episode 03. In that Walter gives the chemical composition of human body. The conversation is as follows Walter White: Let's break it down. Hydrogen. What ...
0
votes
0answers
18 views

To Study Interactions of two molecules in PubChem

Assume you have two substances Diosminum / Hesperidinum. The former strengthens vascular walls. The latter has role in some glycoside biosynthesis. From Biochemistry, I recall that glycodises have ...
1
vote
2answers
13k views

What is it called when one human eye is seeing brighter color than the other?

What is the name of a phenomenon where one of the human eyes is seeing brighter/more saturated color than the other? I can observe the same object from the same position while alternating which eye is ...
1
vote
1answer
29 views

Is Norepinephrine beta2 adrenomimetic?

I know that it has alpha1, alpha2 and beta1 effects. It has beta2 receptor where epinephrine can effect. However, to say that it is beta adrenomimetic, I am not sure. That is ligand binding beta2 ...
5
votes
1answer
176 views

In males, why it is difficult to control orgasm?

Why it is difficult to control orgasm in male humans? How are orgasms controlled and what is different between males and females? We can control urine for few minutes, but we can't control orgasm for ...
0
votes
1answer
20 views

Ephedrine or pseudoephedrine indirectly central alpha2 mimetic?

I started to think this problem by first thinking if the alpha2 mimetism is possible in either case. It seems to be indirectly in either one. Ephedrine seems to have more prominent effect in CNS. ...
4
votes
1answer
34 views

What is 'independent assortment'?

What is the definition of 'independent assortment'. I tried researching this term but came back with two results: alleles assort themselves independently of different alleles the alignment of ...