Category Medical World

Until laser surgery was invented in 1963, someone with a growth, a cancer or a cataract, needed a major operation to have it removed. Now, laser beams can be used in ‘bloodless’ operations to remove growths and even repair tissues, without cutting, less painfully and more safely.

 In laser surgery to remove a growth from the throat, for example, a small tube, or endoscope, is passed down the patient’s throat, under local anaesthetic. A laser beam is directed down the tube along an optical fibre and is focused on the growth. All laser surgery works on this principle of passing light down an optical fibre. The beam is a form of light which carries a great deal of energy. The energy is absorbed by the tissues of the growth, or the skin tissues to be removed, which become hot. By controlling the heat intensity, doctors can burn off — literally vaporise — unwanted cells.

In this way, laser beams are used to cut away cancers, vaporise the dyes in tattoos or get rid of birthmarks.

Another use of laser beams is to heat tissues sufficiently to `weld’ them together — to stop blood vessels bleeding, for example. The operation might be per-formed on a patient who is bleeding from a stomach ulcer.

 The wavelength of the laser beam affects the way in which tissues respond to it. Lasers that use carbon dioxide produce beams of light which are absorbed by tissues at a depth of only 0.1mm. This means that they can be used to make fine cuts in tissue, as a sort of ‘laser scalpel’. Such precision cutting might be used when making incisions in the cornea of the eye to correct defects in sight, or in removing throat tumours.

 Lasers using a metal-based chemical called neodymium produce light which is absorbed by a greater depth of tissue, making it useful to destroy cancers.

Those lasers that use the gas argon produce a distinctive blue-green light, which is absorbed by haemoglobin — the chemical in the blood that gives it its red colouring. Argon beams can therefore be used where haemoglobin levels are high,, in birthmarks.

A further benefit of laser beams is that they allow doctors to reach areas of the body previously hard to get at with a scalpel and to perform operations that were impossible before: to rid arteries of block. Ages of fatty deposits; to sew back detached retinas; to cut a hole through a cataract in a lens and so restore vision; and to cure cancer of the cervix.

 

Picture Credit : Google

On Christmas Eve in 1980, Beatrice Ramos threw herself and her 13-month-old son, Vladimir, under a subway train in New York. Both were badly hurt. Vladimir’s right foot and left leg were injured beyond repair. But to spare him from having two false limbs, surgeons at Bellevue Hospital performed a pioneering operation in which they attached his left foot to his right leg.

Only ten years earlier, such an operation would have been thought impossible. Now, operations to save limbs are much more common.

Microsurgery involves working on the tiniest structures in the human body, such as nerve fibres, veins and fine arteries. When sewing back a severed part of the body, it is not sufficient simply to sew it on. Without connecting blood vessels the part would die from lack of oxygen, and if the nerves were not connected, it would have no nervous stimulation and would be useless.

Since the structures involved are so fine — an artery in a finger is about I/16in (1-2mm) wide and a nerve fibre varies from .002mm to .02mm — microsurgery is possible only with high-powered microscopes. These instruments have a magnification from x 6 to x 40, allowing surgeons to see the tiny structures that need joining up. Micro-scopes with two or three heads have been developed, which allow more than one surgeon to work at the same time.

 When stitching nerves, surgeons have to make sure that they join matching bundles. They are usually identified before surgery.

The surgeon works with a needle which is only 50 microns (.05mm) thick, with 18 micron (nearly .02mm) nylon thread.

When stitching two blood vessels together. A surgeon normally uses a method known as triangulation. Three stitches are made 120 degrees apart at the end of the blood vessels, and then the surgeon sews all the way around their circumference, a third at a time.

It can take 15 to 30 minutes to stitch one vein to another. Stitching back a hand can take 19 hours.

Sometimes blood vessels can be joined together without intricate sewing. By using electrical probes to heat up the severed ends the surgeons can literally weld them together.

After surgery, physiotherapy is essential to restore the replanted limb to working order. For a replanted hand it takes about 200 days for the nerve and blood vessel tissues to regenerate. It takes longer. However, for the part to function normally.

 Apart from repairing injuries, micro-surgical techniques can be used for a host of other problems. Eye operations, for example, involve microsurgery. An eye operation called ‘radial keratotomy’, which was pioneered by Russian surgeons, can sometimes cure short sight. The surgeon makes a number of slits radiating from the centre of the cornea, the surface of the eye. The cuts change the shape of the cornea, which alters the distance between the front of the eye and the retina, bringing objects into focus which previously was not.

Brain surgeons use operating micro-scopes to place their instruments with much greater precision, so improving the chances of success in removing tumors. The microscopes enable surgeons to re-move the tumor without cutting away any normal brain tissue.

 

Picture Credit : Google

There is one dietary regime which has been shown to boost athletes’ energy levels significantly. Known as carbohydrate loading, it increases the level of glycogen in the muscles. Glycogen is a form of glucose which is broken down to release energy. By building up the amount of glycogen they contain, the muscles can work hard for longer.

 The programme usually starts a week before a competition. On the seventh day before the event, preferably in the evening, the athlete performs a strenuous training routine to deplete the glycogen stored in his muscles, and eats a low-carbohydrate meal. During the following three days he trains less and continues with low-carbohydrate meals.

On days three and two the athlete eats a high-carbohydrate diet and eases the training further.

On day one the carbohydrate intake is increased again, and the athlete rests, in preparation for the event the following day.

The principle behind this programme is that when a high level of carbohydrates is introduced to muscles low on glycogen, the muscles overcompensate and take in a higher than normal level of glycogen over a short period. It is these surplus stores that the athlete draws on during his event, which keep him going longer.

 Following this dietary routine, some top-ranking marathon runners have found that their performances have improved significantly.

 

Picture Credit : Google

In Rangoon, Burma, in 1974, a man called Bhandanta, Vicitsara recited 16,000 pages of Buddhist text from memory. That sort of memory is phenomenal, but almost everyone is able to remember surprisingly large amounts of information. Despite this, you forget a new telephone number almost immediately after you dial it.

This apparent contradiction occurs because people have two types of memory. Short-term memory can retain only six or seven items for up to a minute. Long-term memory can retain much more complex information for years and even decades.

Scientists have discovered that short and long-term memory are located in different parts of the brain. Short-term memory is found in the middle of the brain, but long-term memory is located all over the outer part. This is why, when a disease or stroke affects the inner part of the brain, and results in memory loss, the victim can remember events leading up to his memory loss, because they are part of his long-term memory, but cannot store new memories.

Psychologists know that memory is linked to the five senses. During the leading phase, child who has reached the age of six has a vocabulary of 6000 words. Throughout the rest of his life he average person will acquire only another 14,000. Yet the foundations are laid before he can read, so he has learned these sounds by their meaning, rhythm and tone, and by association.

When information is held in the long-term memory, it is probably translated into some kind of picture and stored in the nerve cells in the outer part of the brain. There are more than 100,000 million such cells, each of which has 10,000 connections to other cells, making the network unbelievably complex.

The information in the cells is probably stored by chemicals which after the way the cells work and the way they are connected to each other.

Something in a person’s short-term memory can be transferred to his long-term memory by repetition and learning. The information is actually transferred by chemical messengers. These messengers are molecules which travel from one brain cell to another. Each molecule causes a specific action, and so ‘transmits’  message.

So even though you may forget a telephone number you have just dialed, you can eventually store it in your long-term memory if you are going to read it in the future.

 

Picture Credit : Google

If you have perfect vision, the light rays entering the pupils of your eyes will converge exactly on the retina at the back, and the sharply focused picture will be relayed to the brain.

Most people’s vision is at its sharpest at about the age of one year. Problems often develop at around puberty. The eyeball grows too long from front to back, or not long enough or it becomes misshapen. These are the three most common reasons why pepole need to wear glasses to correct the eye’s focal length.

In early life, a person’s potential sight problems may be compensated for by the strong action of the ciliary muscles attached to the iris of the eye’s lens. These muscles increase or decrease the curvature of the lens so that it is possible to focus on things up or far away.

But if the ciliary muscles weaken as often happens in middle age, the lens can no longer be made thick enough to focus on close-up objects, such as small type on a printed page. A person who at the age of ten could focus on the tip of his own nose may suddenly find that he cannot read a book unless he holds it at arm’s length.

The three main causes of blurred vision are long-sightedness, short-sightedness and astigmatism, and glasses of different types are used to correct them. Tinted lenses help wearers whose eyes are sensitive to light or reflections from clear lenses. An anti-reflection substance can also be used to coat lenses and help to make vision sharper.

Spectacle lenses are made of either glass or plastic. Glass is heavier but it also more resistant to scratching.

 

Picture Credit : Google