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Questions tagged [human-biology]

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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4 votes
1 answer
97 views

Central diabetes insipidus and antidiuretic hormone

Are the levels of antidiuretic hormone in the plasma somehow hard to measure or are the results unreliable, and if so why? Some countries have moved away from testing for ADH (the national health care ...
-1 votes
1 answer
131 views

Why don't women continue to produce ova indefinitely?

Why has the human body not evolved to produce more ova? Is there some technical reason that makes is easy while the fetus is developing, but much harder later in life? Or, perhaps more likely, is it ...
-2 votes
0 answers
33 views

Microplastics affecting hormones

It is apparent that the food being transported and distributed for the mass of society is containing microplastics. Is there any scholarly articles that can be referenced to answer this question. How ...
-1 votes
1 answer
121 views

What is the approx. diameter of a completely "folded up" human DNA molecule, in inches?

The human DNA molecule would be about 6ft if stretched out to a straight line. I'm curious what the diameter of the DNA molecule normally is when it is "all scrunched up" or "bundled&...
3 votes
2 answers
1k views

Can the axial length of the human eye decrease?

I understand that the axial length of the eyeball grows until you are around 20 years of age, which is why hypermetropia decreases with age but myopia doesn't. My question is: can the axial length of ...
-1 votes
3 answers
107 views

Why is the body not able to "detect" imbalances and defects on its own?

We all know, our body is able to roughly localize pain sources or react to imbalances or defects: the stomach hurts because we may have eaten something spoiled, muscles hurts after exercising too ...
1 vote
1 answer
103 views

Information regarding gastroenterology?

Where, online (preferably free) can learn medical topics in depth, specifically gastroenterology? I'll try to be concise and to the point: I have an Associate of Science degree where I actually ...
1 vote
1 answer
68 views

Does the ratio between M and L cone cells vary in one indiviual?

Wikipedia says: The ratio of M and L cones varies greatly among different people with regular vision (e.g. values of 75.8% L with 20.0% M versus 50.6% L with 44.2% M in two male subjects). This ...
0 votes
0 answers
35 views

Are there any supplement or some natural ways for players to increase lactic acid tolerance?

I was reading a chapter called Biomechanics in  Sports." In that chapter, there was a physiological factor determining the performance of athletes called lactic acid tolerance.  Lactic acid ...
14 votes
1 answer
110k views

Dorsal vs Posterior and Ventral vs Anterior

From prior reading, I thought that Dorsal is the same as Posterior and Ventral is the same as Anterior. However, when I checked in google images for these anatomical terms for a horse (just to ...
0 votes
1 answer
368 views

If a person touched an electric eel, would they sustain electrical burns as if they touched a high tension power line?

I've been wondering this, if an eel was continuously shocking someone, would they sustain electrical burns as if they touched a high tension power line due to the high voltage and amps?
0 votes
0 answers
52 views

Why does the throat close up during an allergic reaction?

I was thinking about anaphylaxis and how strange it is that exposure to an allergen, e.g. a peanut, would cause someone’s throat to close up to the point where they can’t breathe. Why does this happen,...
30 votes
3 answers
1k views

Is telomere length a reliable measure of health/lifespan?

Several companies are commercializing tests for telomere length such as this one here. I understand the basic mechanism for why telomeres shorten during DNA replication, but how good is the evidence ...
2 votes
2 answers
225 views

If race doesn’t exist; why do humans look so different?

I was talking about a speculative new race of humans that could be created with genetic engineering and several people told me that race does not exist and is a social construct. I get what they are ...
3 votes
2 answers
132 views

What is H-activation vs. O-activation in the context of cellular respiration?

I was reading this article on Albert Szent-Gyorgyi and on page 7 there's this statement: Now, I thought myself capable of tackling a biochemical problem. I embarked on biological oxidations. At that ...
2 votes
1 answer
44 views

Flow of left ventricle into the aorta

I am currently practising for an exam and am having trouble understanding one of the exam questions: The table gives the blood flow rate in various parts of the fetal circulation. Flow rate in mL min-...
1 vote
0 answers
25 views

Neuronal reflex circuit

I am having trouble understanding an exam question. I am given a diagram which looks like this: I am having a lot of trouble understanding this diagram since it looks unlike the diagrams usually ...
5 votes
1 answer
177 views

Optimal carbon dioxide concentration range for the human body

Previously I had thought the maximum concentration of CO2 for human health to be given by the ‘Pettenkofer CO2 level’ with a maximum of 1000 ppm. But according to this post a growing body of ...
3 votes
3 answers
410 views

Is reverse senescence/"anti-aging" actually scientifically possible among humans yet?

I have been very interested in this since I myself am interested in reversing my skin's aging/genes/damage/etc. I also am interested in volunteering any future genetic altering of skin quality. ...
4 votes
0 answers
79 views

Alzheimer's drug Aduhelm causing viral encephalitis

Over 40% of patients who received Biogen's anti-amyloid beta drug Aduhelm had "brain swelling or bleeding." (See, https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2792897) ...
0 votes
0 answers
41 views

Chromosomes in humans and chimpanzees

I am reading a book titled 'Critical Thinking Skills for Dummies' by Martin Cohen, in which I came across this passage: 'Although humans share 98 per cent of their genes with chimpanzees, they share ...
1 vote
1 answer
141 views

What is the difference between digesting sugar and carbohydrates?

To understand where I'm coming from, first some commonly distributed (mis?)conceptions: (Obviously to be taken with a big grain of salt because they are somewhat contradictory) Sugar is bad for your ...
0 votes
0 answers
62 views

How do organs grow to the exact shape and size?

We all know that organs begin to grow in a foetus around three weeks after fertilization. But how does the body know exactly which shape and size the various organs need to grow to?
0 votes
0 answers
18 views

Human Eye Diagram: question about some dimensions

Does anyone know any of the answers to these questions about this human eye diagram: What points should be the center of the circle for the radius numbers (Rn) in the following diagram? The ...
0 votes
0 answers
34 views

Muscle contraction and closing in of z line/disc

I have studied that during a contraction of myofibril, the globular heads of myosin attach to actin filaments and pull them towards the centre of the sarcomere pulling the z line/disc as well. What I ...
7 votes
1 answer
2k views

Why do haemophillic females $X^hX^h$ die before birth?

I just came across a statement in my book , while reading genetics, that haemophiliac females do not survive till birth (the reason not mentioned here why) . Before posting this question here I ...
1 vote
1 answer
52 views

Is the 5% of the oxygen used in the breathing process fully transformed into CO2?

More specific, I found out that the amount of oxygen we inspire is 21% from the total amount, with 0.04% CO2. The expired amount is 16% oxygen, with 4% CO2. Where does the remaining 1% oxygen go? Or ...
27 votes
5 answers
5k views

Why did scientists state that the Omicron COVID-19 variant was a reason to get a booster?

I was watching Vox’s video, Big questions about the Covid booster shot, answered, which references the New York Times article Omicron Prompts Swift Reconsideration of Boosters Among Scientists. In ...
0 votes
0 answers
29 views

Is the amount of pigment in one feature (e.g. hair, eyes, skin) connected to the amount of pigment in another?

Let's say, genes allowing it, you have a red-haired child with hazel eyes. The hair is a darker/deeper orange color, so (if I recall correctly) having some degree of eumelanin—not much compared to ...
1 vote
0 answers
62 views

Does the duration of the head-hair growth phase differ between men and women?

I found one website which claims the following The growth phase of the hair is called the anagen phase. It lasts about 3 years in men and 5 years in women. Another website makes a very similar claim....
3 votes
1 answer
41 views

What determines if a compound is primarily taken up by the lymphatic extensions rather than the portal vein blood supply in the intestinal villi?

I am currently studying the intestinal absorption/transport systems, but am confused about one part specifically. There are hydrophilic and lipophilic compounds (to varying degrees), and they get ...
0 votes
0 answers
35 views

How long can a hand be submerged in freezing water?

How long can one's hand be submerged in freezing (0°C) water before cell damage starts to occur? What causes the cell damage? I know exposure to temperatures below freezing can quickly cause frostbite,...
2 votes
1 answer
502 views

Can humans metabolize D-malate?

Only the L-isomer is produced naturally, while racemic mixtures are produced synthetically and used commercially as food additives and energy supplements. So what happens when we consume D-malate? ...
0 votes
1 answer
656 views

Human Fat Adipose Tissue: Maximum Energy Transferred out per Day?

The article "A limit on the energy transfer rate from the human fat store in hypophagia" states that subjects with moderate activity levels are found to have a limit on maximum energy ...
16 votes
3 answers
32k views

What is the average speed of human sneeze?

I sneeze a lot, at various times and various "volumes", and often wonder about the speed of the sneeze itself, i.e. the speed of the air coming out of the nose while sneezing. What is the average ...
1 vote
2 answers
468 views

Bacteria and semi-permeable membranes

"The knowledge about semi-permeable membranes is applied for various purposes. We know that semi-permeable membrane is capable of separating substances when a driving force is applied across it. ...
2 votes
1 answer
1k views

Why does exhaled air still contain oxygen?

If the partial pressure of oxygen in the atmosphere is 159 mmHg and that inside human alveoli is 104 mmHg, and if these values are fixed or don't change very much, then why does exhaled air have ...
0 votes
0 answers
15 views

AP2 Binding to LDL Receptor

Is Ap2 always bound to the LDL receptor and only binds clathrin when it detects a change in the LDL receptor, i.e. LDL binds?
0 votes
0 answers
12 views

FH (familial hypercholesterolemia)and LDL Receptors

I'm trying to understand how FH affects LDL receptors. Does FH affect the function of LDL receptors (mutates them) or the number of LDL receptors at the plasma membrane at any given point? Or both?
1 vote
0 answers
59 views

Does Lymph Clot?

According to my professor, lymph has the ability to clot because it contains plasma which has dissolved fibrinogen. He says that as long fibrinogen is present in a bodily fluid, it should be able to ...
1 vote
1 answer
4k views

Would the human body somehow get rid of very fine glass particle(s) that have penetrated the skin?

Assuming that a speck of glass dust has adhered to your finger and after a few days, you notice occasional discomfort when gliding your finger over surfaces (but non if you let the finger alone). It ...
0 votes
0 answers
99 views

Can someone with albinism have red hair with very pale skin and blue eyes?

I have heard of a type of albinism that occurs in races with darker skin that can give people red hair, but in the pictures I've seen, they usually have reddish-brown hair, a medium skin tone, and ...
0 votes
0 answers
141 views

Determining the Length of DNA in a Human Spermatozoon

Hello everyone, I’m currently trying to solve a problem related to DNA length in human spermatozoa and could use some guidance. The problem states: “The DNA of one human spermatozoon contains 10^23 ...
0 votes
0 answers
26 views

What does "the scaffolding of biology" mean here?

In Zoltan Torey's The Conscious Mind, the author discusses the emerge of self-awareness: Turning to the changes that the acquisition of language instantiated, Damasio reflects on these changes in ...
0 votes
0 answers
21 views

What elements are affected when dehydrated?

I know that the blood vessels constrict and there is a decrease in water in the blood. Are there any other elements that increase or decrease when the human body is dehydrated?
1 vote
1 answer
135 views

Potential Function of Knuckle Popping?

Today I was walking past a door, when I accidentally hit my hand on the frame. All my knuckles popped instantly. I got curious and did the same thing but with my knuckles popped and this time the ...
0 votes
0 answers
34 views

Working in heat

What does working in temperatures of 180 degree dry heat for long periods do to the body? Such as inside of a cooking cyclone scraping product out of it while it's still at 180 degrees.
2 votes
1 answer
28 views

Question regarding statistical testing for fractions in low N paired samples

I am unsure about how to analyze some data of my PhD project and could use some input. I am analyzing data from a Phase I clinical trial where we have scRNAseq + Histology of paired PRE and POST ...
10 votes
1 answer
19k views

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?
2 votes
1 answer
38 views

Why is mean systemic filling pressure used to calculate pressure differential for venous return?

I'm really struggling to understand venous return curves and their relationship to mean systemic filling pressure. I understand mean systemic pressure is the pressure that would be measured throughout ...

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