Questions tagged [human-physiology]
For questions on the biochemical, physical, and mechanical functioning of humans in good health including their organs and cells.
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Why do the fastest runners tend to be black?
If you watched the last Olympics like me you probably also observed that most medallists in running events were black. Why is that? I discussed this with university grad friends and researchers and we ...
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Why do human females have periods?
Why do human women have periods when most animals don't? It is known that the unfertilized egg needs to be shed from the uterus. But why shed the whole endometrium? Why didn't evolution put ...
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Why don't chilli peppers taste as hot in space?
The following commentator writes:
Chili peppers don’t taste as hot in space as they do on Earth. Nobody knows why.
We know that the 'hot' feeling of chilli peppers is caused by Capsaicin. We read:
...
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Why is water flavorless?
I read recently that humans have an innate preference for sweet-tasting foods. That seems feasible since carbohydrates are necessary for cells to undergo cellular respiration, but why then is water ...
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Why does hair grow after trimming but remains at a constant length after a while?
Some hair especially body hair regrows after trimming but stops growing after a while. What is the mechanism behind control of hair growth and how is the length limit determined?
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Why can hair grow without limit while eyebrow cannot?
I cut my eyebrow and it grows until reach a certain length. Hair can grow without limit.
Why can hair grow without limit while eyebrow cannot?
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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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Can you bleed from your bones?
I was talking to my science teacher about the body specifically the red bone marrow.
She said that blood is created in the red bone marrow. Does that mean that if you were to cut a fresh bone open ...
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Will the heart keep beating if it's separated from the body?
The heart is a vital organ in our body, as it drives blood circulation. I was wondering if a heart keeps beating if it is separated from the body? If yes, then why?
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Are 'homeothermic' and 'endothermic' synonymous?
I got this question from the comments below this answer. So, do homeothermic and poikilothermic have the same meaning as endothermic and ectothermic, respectively?
A user also suggested that the ...
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Why don't we feel hungry after waking up?
Yesterday, I was fasting (drinking only water until I had dinner at 9 pm). After dinner, I went back to my lab (I am a Master's student) and worked till 1:30 AM. By 1 o' clock, I was feeling quite ...
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How do the biophysics of how cerebrospinal fluid mechanically protects the brain work?
The two mechanisms I've seen mentioned are the cerebrospinal fluid (CSF) acting as a hydraulic cushion or shock absorber, and how CSF creates a micro-gravity environment through buoyancy.
I have very ...
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How deep under water can humans open their naked eyes without damaging them?
Humans can tolerate a maximum pressure of 100atm, but it becomes uncomfortable above 30 atms. Deep divers usually wear protective equipment like goggles among other things and our eyes seem to be more ...
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Do spinal cord reflexes (such as the knee-jerk reflex) continue to function under general anaesthesia?
The knee-jerk reflex (patellar reflex) is an example of a stretch reflex (myotatic reflex). Stretch reflexes are monosynaptic reflexes happening in the spinal cord without involvement of the brain.
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Do humans produce rennin?
At school, we've been taught that human infants produce rennin/chymosin (which aids in the digestion of milk). More specifically, it is the peptic cells in the stomach which secrete prorennin, the ...
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What is the connection between sleep requirement and age?
By this question: Is the human biological clock genetically programmed or learnt? we discussed that the sleep requirement depends on the age of the individual.
- Figure 1. - Sleep requirements by age ...
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How does aspirin "thin" blood?
As we all know, aspirin doesn't actually thin the blood, as it has been explained to me, it makes it "slippery". Slippery blood doesn't stick to itself hence this helps prevent internal blood clots (...
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Upon drinking water for the first time in a long time, why do I sweat?
If I don't drink water for a long period of time (e.g. 10 hours), as during fasting, and then I break the fast by drinking water, I start sweating. Why is this?
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What creates the feeling of 'excess' blood pressure to an area of the body?
If I hang upside down, and feel blood rushing to my head, what structures are actually responsible for me "feeling" this excess flow of blood? Baroreceptors? Mechanoreceptors? Something else?
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Do human anal glands have any function?
Anal glands in all kinds of animals play a range of diverse functions - providing fat for preening feathers or waterproofing fur, generating distinct scent, even repelling predators.
None of the ...
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How is vitamin B12 stored in the body although it is water-soluble?
Vitamin B12 is stored in the liver for a long time.
How is it stored?
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Why some parts of the human body have immune privilege?
Why have the eye and CNS have immune privilege? Why does the body not develop tolerance against their tissue and instead risk their damage in case an accidental immune cell infiltration?
Wiki:
......
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Why does eating saturated fat increase blood cholesterol?
I am interested in the biochemistry of diet and the way we have been advised to eat for the past forty years.
In researching an explanation for the relationship between dietary fat and blood ...
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What is the maximum altitude where humans can survive?
What is the highest altitude that a human can survive without being pressurized? Let's assume that oxygen and heat/insulation are not the limiting factors?
Why I asked.
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Why is there smooth muscle in our bronchioles?
Having muscle tissue in our bronchioles that can constrict seems like a poor choice for tissue. Why would our airway want to ever close up? Wouldn't it be more beneficial for our bronchioles to just ...
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Why antipyretics do not bring the body-temperature below normal?
Antipyretics like paracetamol are used to decrease the body-temperature in fever patients.
But some of them are also used as pain-killers in sprain or other injuries (where there's no fever). In ...
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How fast is the blood flow in various vessels?
How fast is the blood flow in different blood vessels, such as the aorta and capillaries?
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What is the function of the polar bodies produced during oogenesis?
Why are polar bodies produced during oogenesis in human females?
I read that polar bodies are produced during meiosis so that the oogonium (or gamete mother cell) can be converted into a haploid ...
user21723
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Can one eye affect the other eye's low-light adaption?
This previous question addresses how long eyes need to adapt to darkness and reach full contrast. My question is how does one eye affect the "transition" and/or efficacy of this "night vision" of the ...
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Why are we able to differentiate between colored objects without the presence of light?
Rods help us to see during the dark.
We can see colour of the object when it reflects light.
But in a dark room(room of any color but the light is switched off and it is night),we still can ...
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What is the biochemistry of love?
How is love induced between humans? Say, between mother and child, couples, etc.
Does the phenomenon of love exist in other mammals, too?
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When did our ancestors switch to a menstrual cycle instead of the estrous cycle?
The Wikipedia page on the Estrous cycle says:
Humans have menstrual cycles instead of estrous cycles. They shed their endometrium instead of reabsorbing it. Unlike animals with estrous cycles, ...
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Why do we fear the night? [duplicate]
I always feel more afraid in the dark than in light conditions. Is this a common phenomenon in all the people? Does it have biological underpinnings?
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How does increased resistance to flow decrease blood pressure?
I have recently encountered this question:
Waldenström's macroglobulinemia is a condition which causes increased blood viscosity due to high protein content in the blood. How would Waldenström's ...
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Immune System - B-cell receptors
How do the B-cells, which are a part of our body, develop antibodies against antigens of the outside world (outside of our body), which they don't even know about? Is it just a random match?
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Why clotting does not occur during Menstruation
As we know when we get injured our body's clotting systems stop the bleeding. So why does it take days for menstruation to stop ?
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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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What Produces the Postive Potenial in the lumen of the thick ascending loop of Henle?
In the Thick Ascending Loop of Henle, Paracellular diffusion of certain Solutes like magnesium and calcium takes place. Such diffusion is a result of the positive lumen potential.
Looking at the image ...
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Do human populations differ in core body temperature?
Human body temperature is a very complex and tightly regulated system. Hypothermia or fever of only 1-2K (i.e. changes of about 5%) already cause major symptoms and changes of 3-4K (i.e. about 10%) ...
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What happens to the mold spores we inhale?
What happens to the mold spores we inhale?
I'm guessing when we exhale, many of them are expelled back out to the environment.
But given that disease can be caused by mold exposure, I'm also ...
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How does vitamin C increase iron uptake?
I've read that vitamin C increases the iron uptake in the human body. How does that work, physiologically?
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Digestion of milk in humans
The intial step in the digestion of milk in humans is carried out by which of the following enzymes?
A) lipase.
B) trypsin.
C) rennin.
D) pepsin.
I'm confused between the C and D option. as it'...
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Are there neuron mediated reactions faster than reflexes?
I'm interested in how fast the human body can respond to a stimulus. I know the fastest reflex, the blink reflex, operates around 100ms from stimulus to reaction. I also know that the blink reflex ...
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Normal ECG/EKG Measurement?
I'm getting started using ECG using a 3 lead system by iWorx. I have place the leads on my two wrists and the ground on my ankle and have recorded some data into the provided LabScribe 3 software ...
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Does variation in human gut length vary predictably with diet of ancestors?
Background: Numerous online searches, textbooks and other sources seem to pin the average length of the human gut from mouth to anus (oroanal) between about 5-10m in length. To pick a reputable ...
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Why some tissues like small intestine epithelium are able to be replaced so often, yet they are not one of the most common cancers?
My small intestine epithelium cells are replaced thousands times more than my prostate. Yet I'm much more likely of getting a prostate cancer than cancer on my intestine epithelium. Is there a known ...
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Pathogens vs Microbes and the Immune System
I hope my question isn't too basic or silly. I am currently learning about infectious diseases in Year 11 Biology right now, and I'm stuck at the concept of pathogens and micro-organisms. Whenever I ...
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Wim Hof Method claims Alkaline Blood is Good. Contradictions? Counterproof?
The Wim Hof Method claims, that it is beneficial to have alkaline blood.
On the other site there is the medical claim that if the pH-value is not within the
range of 7.36 – 7.42, enzyms are ...
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Cooperativity of haemoglobin and oxygen dissociation curve of haemoglobin
Haemoglobin shows positive cooperativity with oxygen. When an oxygen atom binds to one of hemoglobin's four binding sites, the affinity to oxygen of the three remaining available binding sites ...
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Besides hemoglobin, what proteins are present in red blood cells?
I knew that mature red blood cells (RBCs) lacked nuclei, but I wasn't aware until just now that they also lacked ribosomes and mitochondria. Most cells in the human body all contain a common laundry ...
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