Category Human Body

          Just as an engine needs fuels like coal, petrol etc. to run, similarly our body also requires fuel which provides us energy to work with. The substances which act as fuel or energy for our body are fats, carbohydrates, proteins etc. — the substances which our food consists of. Whatever food we take it gets burnt with the help of oxygen which we get from in-breathing, thereby releasing energy by breaking into these constituents. This energy thus produced is used in the performance of all of our voluntary and involuntary body functions. For instance, protein is required for growth and tissue repair while vitamins and the minerals are necessary for the proper functioning of various body organs.

          So, we need to supply these substances regularly to our body for its efficient functioning. That is why we take food regularly.

          Out of these substances taken as food our body absorbs and utilizes useful ones and rejects those which are not needed, in the form of waste material. We excrete daily about 2 kg of urine and stool. Carbon-dioxide also comes out during out-breathing as a waste material. About 400 gm of water comes out through the process of sweating and out-breathing.

          Human body temperature remains constant between 98°F and 99°F. This is a wonderful equilibrium between the production and consumption of heat in the body so that the body temperature remains constant. Food is measured in units of energy, called Calories.

          Our body is a wonderful machine which works continuously without any break. Even when we are in sleep many processes such as respiration, digestion, heart beating etc. go on incessantly. These processes also consume fuel continuously.

          Cholesterol is an organic compound belonging to the steroid family and occurring either in a free state or as esters of fatty acid in practically all animal tissues. The molecular formula for cholesterol is. In a normal man it is about 0.3 percent of his average weight. It is the starting material from which the body produces bile acids, steroid hormones and pro-vitamin substances in the body. It is used by our body to help the digestive system as well.

          Cholesterol was discovered in 1812. Its name arises from its occurrences in gallstones derived from the Greek word chole-stereos-ol meaning bile-solid. The synthesis of cholesterol occurs in various tissues and organs particularly, the brain, liver and arteries.

          The increase in its quantity beyond a certain level can be harmful for our body. Excess of fat and cholesterol get deposited in the walls of arteries causing blockage and hardness thus obstructing the free flow of blood. Due to this, quantity of blood flowing in the arteries decreases and consequently the oxygen supply to vital parts of our body is also decreased. This condition is medically termed as arteriosclerosis. Small blood clots that would normally pass through blood vessels may get trapped by high cholesterol deposits.

          We know that coronary arteries play a vital role for the heart to function. They provide oxygen and carry blood to the heart. If a coronary artery gets blocked that particular part of the heart may stop functioning leading to a major heart attack which can even prove fatal.

          Cholesterol in blood can be controlled by a regulated diet. A high concentration of cholesterol is present in the foods of animal origin like meat, egg, butter etc. Doctors advise to avoid high-cholesterol foods by substituting unsaturated foods like fruits, vegetables, cereals and so on.

          Lowering cholesterol levels in the blood can help to reduce the risk of heart attacks. Several other measures can be taken to maintain the desirable cholesterol level. This includes giving up smoking, regular exercises, avoidance of overeating and fatty substances.

          It is a matter of common experience that when we feel cold or frightened, tiny bumps, causing a tingling sensation, appear on our skin. These tiny bumps are called goose pimples. Do you know why these occur?

          The ‘goose pimples’ get their name from the actual bumps which appear on a goose’s skin when its feathers are plucked.

          If you have a close look at the bumps, you will see a hair in the middle of each bump. Attached to each hair inside your skin is a tiny muscle. When you get scared or chilled, messages go shooting off from nerve endings that pick up the feel of cold. In a flash, signals come back to the muscles and as a result each of these muscles tightens up and gets taut. The skin around each hair is also pulled up. The result is little bumps.

          This action of the hair standing on its end – actually keeps the outside air closer to the body and helps to keep it warm in case of chill. If you rub your skin the goose pimples disappear due to the warmth produced by the rubbing.

          The fur of the animals also rises up due to the same reason. The erector muscle of each hair automatically contracts and the hair stands upright. This is why a cat looks bigger on cold days. This serves a definite purpose in case of animals having fur on their skin. When our ancestors, millions of years ago, had more hair on their body, probably the hair helped them in keeping their body warm. 

            Sexual reproduction is a naturally gifted process by which human beings as well as other higher animals produce their offspring. This process involves the meeting of a male cell with a female cell to produce a fertilized egg which grows and develops into a new creature. The growth of a human body inside its mother’s womb, starting from the fertilization of cells till the birth, is a nine-month long process.

            To begin with, a fertilized egg is formed by the union of male and female sex cells called sperm and ovum respectively. The fertilized egg is termed as zygote. It settles inside a specific place in the mother’s body called the uterus. Almost immediately after it is formed, the zygote begins to divide – and in less than 30 hours two cells are formed, called blastomers. These two cells are absolutely alike. The repeated cell division, rapidly increase the number of blastomers. But then all these cells are not alike. Some are muscle cells, some are bone cells some others are nerve cells, blood cells and so on. In short, all the different kinds of cells that make up a human body are present. 

Continue reading “How does a human baby grow inside its mother’s womb?”

          The scope of heart surgery has vastly increased ever since the introduction of the heart-lung machine in the 1950s. This machine pumps blood from the veins to the arteries without having to pass through the heart. Most of these machines oxygenate the blood, thus completely bypassing the lungs as well. By using this machine, the heart can be stopped and opened for upto four hours.

          In human heart transplant, the main problem was that the body’s natural defence system tended to reject a new organ. The problem was eventually eased by the discovery of the fact that if the tissue types and the blood group of both people were carefully matched, the person receiving the heart had a much better chance of survival. 

          It was because of the use of such modern techniques and apparatus that the first human hearts transplant became possible. It took place on December 3, 1967, at Groote Schuur Hospital, Cape Town, South Africa. A team of 30 surgeons, headed by Dr. Christian Barnard, operated on Louis Washkansky, aged 55. The donor was 25 year old Denise Ann Darvall who had been killed in a road accident. 

Continue reading “When did the first human heart transplant take place?”