Why your fingers shrink when soaked in water and Why you lose your voice after screaming

Some questions people ask ....

Water can make skin on our fingers and toes wrinkly. Why does that happen?

Earlier people used to think osmosis is responsible for this. But that is not true. Because researchers noticed that it didn’t happen to people with nerve damage to the fingertips or toes. That meant the wrinkling was part of an involuntary (automatic) response of the nervous system.

Pruney fingers and toes are actually caused when blood vessels just below the skin shrink — a process called vasoconstriction. When your nervous system is functioning properly, soaking in water sends a message through the nerves telling those blood vessels to shrink. The loss of blood volume makes the arteries, veins and capillaries skinnier. Then the skin over them collapses into wrinkles.

Creating temporary wrinkles might have to do with evolutionary advantage. Those wrinkly fingertips might help you grip things better.

If you’ve got some marbles, try picking them up first with dry fingers and then with presoaked, pruney ones. That’s the experiment scientists did to test whether wrinkled fingers gripped better. They did.

As to your toes, they haven’t tested those yet. But when you have to move fast on wet ground, wrinkly toes might have better gripping qualities too. And that might have made a difference to some distant barefooted ancestor fleeing a predator in the rain.

Now why you lose your voice after a few hours of screaming ....

When you talk, sing, shout, or scream, the voice sounds you make happen because of the very fast vibration of your vocal cords.

These vocal cords are two small folds of muscle in your voice box which is in the front of your neck.

Your vocal cords make sound by vibrating many times each second.

If you gently put your fingers around your voice box and say “ahhh”, you will feel your vocal cords vibrating.

When you make sounds, your vocal cords open and close many times each second (move apart and together again) to make the air vibrate.

The opening and closing is like putting your palms together, and then separating them but keeping the tips of your fingers touching. Each opening and closing is one vibration.

Vocal cords: the first is open, the second is closed

A grown man’s vocal cords open and close about 120 times each second when singing “ahhh”.

A kid’s vocal cords open and close more times per second than an adult’s. Their vocal cords are also smaller. This is why children’s voices sound higher.

Now think how much you normally talk, and you can see that your vocal cords are vibrating many thousands of times over a whole day.

When you yell or scream, you are bashing your vocal cords together extra hard with each vibration. This can make you get a hoarse voice.

If you imagine doing that with your hands many times over, they would get red, sore and swollen.

This is what is happening to your vocal cords. They can’t vibrate properly when they are swollen so the sound of your voice will change. 

Sometimes, the swelling and soreness continues to develop for a few hours after screaming.

This is why you might be able to talk right after yelling but only notice losing your voice the next day.

Source of the second explanation: 

https://theconversation.com/curious-kids-why-might-you-wake-up-with...

Why COVID 19 is killing more men than women ...

Yes, this is true. But why? Is it genes, hormones, the immune system – or behaviour?

Experts say it as an interaction of all of these factors and it isn’t unique to the SARS-Cov-2 virus – the different response of men and women is typical of many diseases in many mammals.

One major variable in severity of COVID-19 is age. But this can’t explain the sex bias seen globally because the increased male fatality rate is the same in each age group from 30 to 90+. Women also live on average six years longer than men, so there are more elderly women than men in the vulnerable population.

The other major factor is the presence of chronic diseases, particularly heart disease, diabetes and cancer. These are all more common in men than women, which might account for some of the bias. 

Men and women are biologically different . Men and women differ in their sex chromosomes and the genes that lie on them. Women have two copies of a mid-sized chromosome (called the X). Men have only a single X chromosome and a small Y chromosome that contains few genes.

It’s the hormones that control most of the obvious visible differences between men and women – genitals and breasts, hair and body type – and have a large influence on behaviour.

The Y chromosome contains hardly any genes other than SRY but it is full of repetitive sequences (“junk DNA”).

Perhaps a “toxic Y” could lose its regulation during ageing. This might hasten ageing in men and render them more susceptible to the virus.

But a bigger problem for men is the male hormones unleashed by SRY action. Testosterone levels are implicated in many diseases, particularly heart disease, and may affect lifespan.

Men are also disadvantaged by their low levels of estrogen, which protects women from many diseases, including heart disease.

Male hormones also influence behaviour. Testosterone levels have been credited with major differences between men and women in risky behaviours such as smoking and drinking too much alcohol, as well as reluctance to heed health advice and to seek medical help.

The extreme differences in smoking rate between men and women 

Two X chromosomes are better than one

The X chromosome bears more than 1,000 genes with functions in all sorts of things including routine metabolism, blood clotting and brain development.

The presence of two X chromosomes in XX females provides a buffer if a gene on one X is mutated.

XY males lack this X chromosome backup. That’s why boys suffer from many sex-linked diseases such as haemophilia (poor blood clotting).

The number of X chromosomes also has big effects on many metabolic characters that are separable from sex hormone effects, as studies of mice reveal.

Females not only have a double dose of many X genes, but they may also have the benefit of two different versions of each gene.

This X effect goes far to explain why males die at a higher rate than females at every age from birth.

And another man problem is the immune system.

We’ve known for a long time that women have a stronger immune system than men. This is not all good, because it makes women more susceptible to autoimmune diseases such as lupus and multiple sclerosis.

But it gives women an advantage when it comes to susceptibility to viruses, as many studies in mice and humans show. This helps to explain why men are more susceptible to many viruses, including SARS and MERS.

There are at least 60 immune response genes on the X chromosome, and it seems that a higher dose and having two different versions of these gives women a broader spectrum of defences.

Sex differences in diseases – the big picture

Sex differences in the frequency, severity and treatment efficacy for many diseases were pointed out long ago. COVID-19 is part of a larger pattern in which males lose out – at every age.

This isn’t just humans – it is true of most mammals.

Are sex differences in disease susceptibility simply the by-catch of genetic and hormone differences? Or were they, like many other traits, selected differently in males and females because of differences in life strategy?

It’s suggested that male mammals spread their genes by winning competitions for mates, hence hormone control of risky behaviour is a plus for men.

It’s also suggested female mammals are selected for traits that enhance their ability to care for young, hence their stronger immune system. This made sense for most mammals through the ages.

So the sex bias in COVID-19 deaths is part of a much larger picture – and a very much older picture – of sex differences in genes, chromosomes and hormones that lead to very different responses to all sorts of disease, including COVID-19.

Third story source: https://theconversation.com/why-do-more-men-die-from-coronavirus-th...