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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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,...
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Central diabetes insipidus and antidiuretic hormone
Are the levels of antidiuretic hormone in the plasma somehow hard to measure or are the results unreliable (how so)?
Some countries have moved away from testing for ADH (the national health care ...
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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 ...
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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-...
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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 ...
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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 ...
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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) ...
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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 ...
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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?
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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,...
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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....
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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? ...
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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?
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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?
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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?
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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 ...
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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.
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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 ...
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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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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&...
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Why can't your little finger move independently to your ring finger [duplicate]
If you attempt to curl either your little or ring finger, you will feel a noticeable about of pressure, then the finger you try to keep stationary ends up moving as well. What keeps the two from ...
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How to convert Kilo Units (KU) to mg? [duplicate]
Im searching for AChE (Acetylcholinesterase) and on sigma-aldrich it is showing 2 KU or 2000U/mg of protein and on MedChemExpress it is showing 50mg then how can we calcute how much will be the drug ...
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Would anaerobic glycolysis create more ATP than aerobic respiration
I know the fact that anaerobic glycolysis is first step of aerobic respiration.
If fast twitch muscles use anaerobic glycolysis to get 2 atp at rate that 100 times faster than oxidative ...
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How can saliva neutralise acids produced by bacterial cells in our mouth if it is itself acidic in nature?
My school textbook makes the following claim:
This means that saliva must be basic. However, I learnt that the pH value of saliva is about 6.8, which would surely make it acidic. How can the above ...
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Is it possible for a non-self antigen to NOT be recognized by the body?
The amazing diversity of antigens that the body can recognize (by virtue of T and B cells that express receptors complementary to them) is truly fascinating. The explanation mooted for this is the ...
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How to calculate average Corneal Thickness?
I have a question which I may be making out to be a lot more complex than it actually is.
In my department we have a machine which can image the cornea and give values of various parameters (eg ...
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Minimum conditions for human life
I don't know so much about biology, my strengths it is in physical science and mathematics.
Well i like rifle shooting, I don't hunt, i think that is cruelty and coward.
In some conditions of temp,...
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50-400 bps consciousness: why do we draw the line there?
I have found studies that suggest the human consciousness can process 50 to 400 bps. The exact number varies, but it's always quite small. It is usually associated with some test results, but how do ...
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What is health?
I was studying human health and diseases in a book and first it defined general health as: “The overall complete physical, social, and mental well being.” It further went to say that health is being ...
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Does binge watching cause sleep problems?
According to a study from 2017, binge watching is correlated with various sleep problems:
The people who reported binge-watching were 98 percent more likely to report poor sleep quality compared with ...
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Reason for sorbitol synthesis in human body
Sorbitol has been proved to be a major contributor to development of complications due to chronic diabetes.
It forms in retina, lens, kidneys, peripheral nerves, ovaries and seminal vesicles by the ...
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How does $\ce{H2CO3}$ form in the blood with a ratio of 1:20 with $\ce{HCO3-}$ if there are not enough $\ce{H+}$ ions
I have recently been studying about the bicarbonate buffer in the blood and have a doubt regarding the concentration of carbonic acid in the blood plasma.
My understanding of the buffer system is that ...
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Would using positive numbered glasses while using a computer help prevent myopia?
There are multiple web pages linking screen-time and myopia. While this is not necessarily proven, for example as shown on the NIH page here https://pubmed.ncbi.nlm.nih.gov/31943280/ , it seems ...
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What are all the possible abnormalities in our body that will result in ataxia?
So I know that ataxia is caused by loss of proprioception.I only know that dorsal column medial leminiscal pathway carries proprioceptive fibre to the cerebellum.So in theory damage to either this ...
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Why do so many pollutants affect the estrogen receptor?
We make loads of chemicals, and release them into the environment for reasons. We have loads of hormone receptors.
There are many instances of human made chemicals affecting the estrogen receptor, ...
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What percentage of Lithium compounds pass the blood brain boundary?
I've been doing some research on lithium. Lithium is used in psychiatry as a medicine for mania and bipolar. This is generally a high dosage of lithium carbonate, with around 300mg of elemental ...
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Why does SNS engage epinephrine/norepinephrine (at the effector organ) while the PNS uses acetylcholine?
Why does SNS engage epinephrine/norepinephrine (at the effector organ) while the PNS uses acetylcholine?
Is there some advantage of E/NE in terms of being faster or more long-lasting vs. AcH that ...
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Why does hyperventilation make you feel like you need to breathe more?
Calm Clinic claims:
"The problem is that hyperventilation makes your body feel like you're not getting enough oxygen. Essentially, it makes you feel like you need to take deeper breaths and take ...
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Are there any "good" gases which "accidentally" diffuse into the lungs and get exhaled?
The purpose of breathing is to bring oxygen into the body and to rid the body of waste gases such as carbon dioxide and excess water vapor. This is done by diffusion with the blood. I am wondering ...
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Is it possible to focus only one axis of astigmatism?
When we look at something close, we focus our eyes as a circle. But what if someone has astigmatism and focuses on something close, is it possible for the eyes to "focus" only the axis that ...
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