Why do we shiver when we’re ill? (II)

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By Good Health

1. WHY ARE OUR HEARTS ON THE LEFT SIDE?

Like many of our organs, the heart is not in the very centre of the body but is located slightly to the left, behind the sternum (breast bone).

‘The reason there are asymmetries in the first phase of our development is to do with evolution,’ says Dr Rajay Narain, a research cardiologist.

‘As our digestive, circulatory and central nervous systems got more complex, Nature had to find ways of packing everything into our bodies. Having everything centrally located is an inefficient use of space.’

Some one in 10,000 people have situs inversus, where all the major internal organs are on the opposite side of the body from normal. Yet this is unlikely to cause harm.

Everyone needs reading glasses eventually because as we age the lenses in our eyes becomes less elastic, meaning they cannot change shape to focus on nearby objects as well

2. DOES EVERYONE NEED READING GLASSES EVENTUALLY?

Basically, yes, according to Robert Scott, consultant ophthalmologist at the BMI Priory Hospital.

‘Your lens keeps growing throughout life, getting denser and less elastic than it used to be. This means the ciliary muscles [which help squeeze or stretch the lens to help it focus on an object] can’t do their job so well.’

The process of changing the shape of the lens is called accommodation.

From the age of 35, people tend to lose accommodation to the extent that they need reading glasses to help them focus on an object 30cm away — this is known as presbyopia.

There are books that aim to teach you how to make these muscles stronger — such as by training your eye to look at smaller and smaller letters — but Mr Scott is not convinced they are effective.

With a bit of training, most people could learn to wink with both of their eyes, an expert said

3. WHY CAN I ONLY WINK WITH ONE EYE?

With a bit of training you could probably learn to wink with both eyes, says Professor Scott.

‘Sometimes, people have a damaged nerve, due to injury or disease, and can’t wink. But most people should manage it with practice.

‘The obicularis muscle, which closes the eyelids, is supplied by nerves on both sides, so can be worked independently.

If you can close both eyes, you can probably train yourself to wink.’

However, some people still struggle and find they can wink only with the one eye, which tends to be the same side as the hand they write with.

In right-handed people, the brain’s left hemisphere is thought to be dominant — this hemisphere controls the right side of the body.

‘Winking is also connected with ear waggling and raising your eyebrows,’ adds Professor Scott.

‘If you can wiggle one ear and not the other, it tends to be the right ear.’ So, you may be able to learn to do it on both sides.

4. WHY DOES SQUINTING MAKE THINGS CLEARER?

Squinting reduces the amount of light coming into the eye, explains Professor Scott.

By limiting the rays that come through the top and bottom of the pupil, the light that does get in is ‘relatively undeviated’, allowing rays to pass closer to the centre of the lens.

This cancels out the effect of being long or short-sighted, where the light is normally deviated.

As a result, the light focuses better on the retina, the layer of cells at the back of the eye that transmit images to the brain. ‘It’s a bit like looking through a pinhole,’ says Professor Scott.

You can take advantage of the pinhole effect, which has been known about since the 10th century, to make a DIY pair of reading glasses by putting pinholes in cardboard and looking through them.

Squinting makes things clearer by turning the eye into a ‘pinhole’, which cancels out short-sightedness

5. WHY DOES STICKING FINGERS DOWN YOUR THROAT MAKE YOU THROW UP?

When the brain perceives something that shouldn’t be there, the body tries to repel it.

Nerves around the tonsils and at the back of the tongue are very sensitive, as their function is to make sure that nothing that is potentially hazardous is swallowed.

When these nerves detect we’re about to swallow something bad or that might block the airway, we gag.

‘If the hazard remains, that becomes a retching reflex [dry vomiting],’ says Dr Christian Potter, an ear, nose and throat specialist at Torbay Hospital in Devon.

‘Then it becomes a vomit. It’s a throwback to animals that throw up on predators to make themselves less desirable.

‘Humans are unusual among mammals for being able to vomit.’

Source: Dailymail.co.uk