During the past two decades bio-engineers have developed a number of artificial substitutes for diseased tissues and organs. Some of these, such as, kidney dialyzers are external devices. Other such as plastic heart valves and artificial blood vessels are implanted inside the body, replacing the diseased or damaged ones. Two devices – the dialyzer and artificial heart valves are of special interest.
The artificial kidney or dialyzer performs the function of removing wastes from the blood of a person whose kidneys do not work properly. It is an external device and patient needs dialyses twice a week. With this machine a person can be kept alive for years.
In April 1969, Dr. Denton A. Cooley of St. Luke’s Episcopal Hospital in Houston placed a Dacron and silastic heart (artificial heart) into a dying man. Three days later a cadaver heart became available and was used to replace the artificial device. The next day the patient died. Some 13 years later, at the university of Utal medical centre, an artificial heart powered by a 170 kilogram external system, was implanted in the chest of 62 years old Barney Clark. He died 112 days later of multiple organ collapses. The heart was in perfect working condition.
In 1984-1985, several artificial heart implants were performed in the United States and Sweden. Good life spans have been achieved but against a tremendous cost.
Artificial teeth have been used by humans for a long time very successfully.
The heart, the lung, the liver, the kidney, the adrenal glands and cornea can be transplanted from one human being to another. Success rate of transplantations of human organs is much higher than that of artificial parts.
It is the store of things learned and retained from our activity or experience. Our memory is a collection of knowledge, experiences, impressions, skills, habits, and many other things. It gives us the ability to learn and adapt from previous experiences as well as to build relationships. It has a lifelong storage capacity, and no computer of the world can match its performance. Short-term memory is the information that we are currently thinking of and it lasts for only a few seconds. Important things which we have experienced and would not like to forget are transferred from short-term memory into long-term memory.
The brain is made up of two halves. Different areas of the brain have different functions. All nerve cells in the brain, about 100 billion of them, are connected to one another and transmit information. This network of the nerve cells is expanded through learning and training. Our brain controls our actions, regulates our sleep, and allows us to feel sensations like pain and joy. If it is damaged, maybe due to a stroke, one has to relearn a lot of things like speaking, walking, or eating.
Our balancing organs in the inner ear are three semicircular canals filled with fluid and with fine sensory hair. These hairs sway with our movement and transmit the changes to the brain. The eyes and the foot confirm these movement signals. When we spin around and then stand still, our brain gets confused with different messages: the balancing organs say that we are still moving, but eyes and body convey a different message – and we become dizzy.
Our sense of smell in responsible for about 80% of what we taste. The taste buds present on our tongues are limited to only the basic sensations: sweet, salty, sour, and bitter. All other flavours that we experience come from smell. This is why, when our nose is blocked, as by a cold, most foods seem bland or tasteless. Our sense of smell can normally detect up to 10,000 smells.