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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29 views

Can the basement membrane of blood capillaries expand?

I have been doing some rudimentary research into the basement membrane and found the it contains collagen fibers which are known for their elasticity. Does this mean that the basement membrane can ...
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SNP Genotyping Scanning technology

The silicon bead micro-array technology for SNP scanning is a marvellous example of human ingenuity. Is anyone aware of a non-technical history of its development accessible to the lay reader? As an ...
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Why are the sympathetic and parasympathetic axons different, in terms of presynaptic and postsynaptic length?

Does the parasympathetic system have a long presynaptic efferent axon because it takes a great distance to reach target organs from the brain stem or sacral region of the spine? Does the sympathetic ...
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45 views

Is there an antidote for caffeine, e.g. as a supplicant for caffeine-intolerant persons?

First, let me state I'm not talking about a medical emergency. No one is in a serious condition. My girlfriend is, we think, caffeine-intolerant. She loves the smell of coffee and the habit of coffee ...
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2answers
48 views

Why is there a distinction between an *allergic* and an *immune* response?

Our immune system has evolved to protect us against potentially dangerous non-self particles. I have difficulty in understanding why there is a distinction called an allergic response: what’s wrong ...
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60 views

Can the shoulder bones grow after the growth plates have fused?

Body builders have broad shoulders. If one start lifting weights after one's growth plates have fused, can one still increase the width of one's shoulders? If yes, does that mean shoulder bones can ...
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1answer
62 views

If Melatonin is anti-gonadal, why is it associated with early sexual maturity in congenitally blind girls?

If melatonin is anti-gonadal, that is, it delays sexual maturity, then shouldn’t it delay sexual maturity in congenitally blind girls rather than helping them attain sexual maturity at an early age?
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46 views

Does the human eye’s field of view shrink when focusing on far away objects?

It seems like the lenses of the eye is like a fisheye lens that flattens out to a normal lens when looking at far away objects. Does that also mean that the field of view gets narrowed down as well? ...
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58 views

When did humans or their ancestors gain the instinct to take shelter?

I was going to ask if seeking shelter in a constructure dwelling or natural formation was instinctive to modern humans or if it is a learned sociatal behaviour. By shelter I mean seek routine ...
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2answers
81 views

How does the energy we get from food transform into mechanical motion at the cellular level?

I am curious how, when we consume food which is broken down into glucose, powers the movement of the associated proteins in the muscle for example? Is the thermal energy converted to kinetic energy ...
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41 views

Why is cognitive maturity related to organism lifespan in larger animals and mammals?

I am not a student of biology, so I should provide some context to me asking this rudimentary question. While doing a graduate-level course on Reinforcement Learning, the instructors focused on how we ...
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72 views

Why does hypocalcaemia cause increased muscle contraction?

Calcium is needed for muscle contraction, so how does hypocalcaemia cause increased sustained contraction?
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10 views

Why are the retina layers arranged the way they are? [duplicate]

The retina layers are arranged in such a way that light has to pass through several layers before hitting the photosensitive cells. Won't this be much better if the photosensitive cells made up the ...
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2answers
60 views

What is the meaning of the word “Ligandable” in “ligandable proteome”?

I see "ligandable proteome", "ligandable proteins" and "ligandable targets" an awful lot. But really I don't know what exactly the word "ligandable" means? Is that it means, for example, "ligandable ...
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34 views

What is the relation between “classes” (stem cell, proliferative and differentiating) and the types (Ad, Ap, B) of the spermatogonium?

Describing the question in the title further, The section, Systems Toxicologic Pathology, Dianne M. Creasy, Robert E. Chapin, in Haschek and Rousseaux's Handbook of Toxicologic Pathology (Third ...
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When is it viable to remove old graves?

Societal considerations aside, when all the remaining relatives of a particular gravesite have all disappeared or forgotten about a certain grave, is it viable/hygienic to remove or repurpose old ...
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1answer
44 views

What fraction of human cells gets infected during a viral infection?

As I understand, if a cell gets infected during a viral infection then it eventually dies. If an individual does not die of an infection, the percentage of cells that gets infected in the course of ...
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1answer
65 views

Do pinhole glasses help reduce eye strain?

I've noticed that I can read about 10x longer at screens and books without my eyes tiring using the "pinhole trick" - where you curl your fingers and look through the hole (great explanation here ...
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39 views

Why does insertion of transmembrane domains occur in the rough ER?

To elaborate on that question, why in the secretory pathway does the insertion of transmembrane domains into the membrane occur in the rough ER as the protein is translated and threaded across the ER ...
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6 views

Is it possible to lose more than gain more fluids by sweating due to drinking very hot water?

It's an extremely hot day today (about 40 degrees celsius) and I made myself a hot cup of tea, when I drank it I sweated profusely and wondered if it's possible I lost more fluids by sweating than I ...
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13 views

Do L cone cells have a secondary peak?

I found some pictures on the internet suggesting that L cone cells (an in some M type too) have a secondary peak in the blue part of the spectrum. Is that so? Why would that be? (As if there is not ...
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7 views

What are different stages of living in abnormal pressure?

On the top of the Earth's highest mountains the pressure is too low for a human to breathe without oxygen mask. This is because the partial pressure of oxygen becomes so low that breath can't fill ...
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1answer
55 views

Why do viruses cause different symptoms?

If the sole purpose of a virus is to hijack the nucleus of a cell to replicate, why do we have different symptoms for different viruses? I can think of the following comming into play: immune ...
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23 views

How it will taste if one puts two substances on tongue simultaneously?

If we put two substances having different taste on tongue simultaneously how it will taste? Does specific part of tongue is sensitive to specific taste?
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35 views

Is it possible to make synthetic olfactory receptors?

Are there any electronic engineering technologies that allow people to make synthetic olfactory receptor that generate electrical impulses when exposed to certain proteins or molecules? If not, what ...
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10 views

Does the brain absorb heme and non-heme iron differently?

I know that for the brain to absorb iron, the iron must first pass through the blood brain barrier. Is this absorption different for heme and nonheme iron?
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How does lactic acid cause muscle twitching?

It is well-known that lactic acid buildup (often caused by workouts) causes muscle twitching. Does anyone know HOW lactic acid achieves that effect?
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216 views

What is the cause of a protuberant belly in kwashiorkor?

Kwashiorkor is a PEM (Protein–energy malnutrition) usually characterised by a pot belly. Why is there a pot belly in the case of a malnutrition? I have found contradictory reasons. This paper says ...
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1answer
54 views

Unlike humans, why do plants not have something blood-like to transport $O_2$ throughout their body?

Since plants have a large number of stomata at different parts of their body, they can get $O_2$ at almost every part of the plant and so, they don't need to transport it throughout the whole body ...
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45 views

If heparin is an anticoagulant, how is its effect nullified upon exposure to air?

First of all, does heparin always remain in circulation? Or is it specifically released by the mast cells and basophils upon activation? Adding to that, if it always stays in circulation, why is its ...
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13 views

What is the lowest pressure differential for which an air embolism as been observed?

Scuba divers can suffer air embolism if they ascent too quickly. If I understand correctly one of the involved factor is the difference between deepest water pressure the divers was in and the lowest ...
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57 views

Aging: Only humans have grey hair?

I am not sure if I ever saw a monkey or a bird age and lose hair pigment as it grows. It maybe due to my lack of information. But it appears to be a general presumption that only humans age and lose ...
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Is this trial that reversed aging in humans worth taking seriously?

In September 2019 Fahy et al. published results from the TRIIM (Thymus Regeneration, Immunorestoration, and Insulin Mitigation) trial. Their stated goals were to investigate whether they could restore ...
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Why do scientists perform most of biological experiments done on rats prior to humans? [closed]

Why do scientists perform most of biological experiments done on rats prior to humans? Scientist gave a third ear to this rat Source Here is the another source claiming Researchers wants ...
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1answer
13 views

Does a tubular sodium reabsorption cause a stimulation of β2-adrenergic receptors?

I read the study "The Role of Aldosterone in Obesity-Related Hypertension" and there is one thing I didn't understand. They write: "According to norepinephrine-induced tubular sodium reabsorption, ...
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9 views

Which results in greater energy expenditure: consecutive actions, or non-consecutive actions?

Is there a difference in energy expenditure when performing the same set of movements consecutively vs non-consecutively? Example: You jump in-place 1 time, stand motionless for 1 minute, and then ...
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1answer
51 views

Sickle-cell trait : Why is only one type of beta chain found in any one hemoglobin molecule?

I was reading a textbook (iGenetics, 3rd edition page 71), and came across the following passage: Homozygous bS bS people make Hb-S, the defective hemoglobin, with two normal a chains specified ...
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72 views

Are there any solid inorganic compounds that are part of the human body?

I'm more interested in parts physically attached to the body, if that makes sense.
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19 views

Overcoming palmitic acid intolerance

What can stop the body from being able to process or break down palmitic acid? The acid stays in the stomach and burns causing a similar reaction as heart burn when the volume is high. Heart burn ...
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33 views

How Do Pressure and Temperature affect arthritis?

Here, in Houston Texas we were hit by a cold front tonight and I remembered the old saying that I'm sure you've all heard "My joints hurt, must be a storm (or change in weather) coming in". It piqued ...
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53 views

How far can free radicals from UV radiation diffuse through the skin?

UV radiation damages DNA through two separate mechanisms. Direct damage occurs when a photon is absorbed by DNA. Indirect damage occurs when a photon is absorbed by a chromophore, and the excited ...
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217 views

Is touching or inhaling 70% isopropyl alcohol dangerous to humans?

I bought 99% isopropyl alcohol and made 70% alcohol + 30% water in small spraying bottles as a disinfectant. I also read that this solution is safe and recommended by Apple for cleaning iPhones. My ...
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53 views

Can catecholamines degrade back into tyrosine, or, is synthesis irreversible? (in human body)

Catecholamines like dopamine, noradrenaline and adrenaline are broken down with enzymes that catalyze the reaction. Can they degrade back into tyrosine (a conditionally essential amino acid), or is ...
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21 views

What causes the overactivity of keratin production and expression in the cells of the nail bed/ nail matrix after some traumata?

What is the cellular mechanism of traumatic(sterile) onychodystrophy(hypertrophy)? I.e one hits his toenail and has it removed twice( once after the first trauma and then again 3 years after the first ...
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72 views

Can far-UVC light be safely used as germicide? (help understanding a paper)

I've been trying to familiarize myself with the literature on far UVC light as a germicide. My question mostly pertains to figure 4 of this paper. The paper investigates the efficacy of 207 nm light ...
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21 views

Can humans eat a greater variety of things than other omnivores?

One thing that I've always noted is that humans seem able to eat just about anything that isn't toxic (and many things that are). Even when compared to other omnivores, I have the impression that ...
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71 views

Is it true that if a human lived long enough (up to 3-400 years), he/she would eventually develop cancer?

I have just studied DNA, but I am not so clear. So, I would like you to explain it more clearly. This is what I think when a human grow older and older, his or her DNA repair mechanism would be ...
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36 views

When does LH surge actually occur?

I’ve seen many textbooks saying that LH surge occurs in the Follicular phase while others say it occurs in the Ovulatory phase. I’ve tried googling this, only to end up knowing two things: 1) It ...
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45 views

Does animal based food contain molecules that behave like dietary fiber for humans?

I have read that dietary fiber is beneficial to human health in many ways, for example that it can help to reduce risk of colorectal cancer. However, when I look at nutrition labels on food it seems ...
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44 views

Does the composition of a meal play a big, or small, role in food's thermogenic effect on the body?

Reading in: "Diet and Health: Implications for Reducing Chronic Disease Risk / Calories: Total Macronutrient Intake, Energy Expenditure, and Net Energy Stores" [NCBI Resources]: "The thermogenic ...

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