Category Zoology

               The appendix is a part of the intestine in the human beings. Its full name is the vermiform appendix. The word vermiform means worm-shaped. The appendix is found on the lower right side of the abdomen. It is found at a place where our small intestine joins the large intestine. This is called caecum. It is in the form of a tube whose one end is closed and the other opens into the caecum.

               In human beings the appendix is usually three to four inches or eight to ten cm. long and less than half an inch wide. It was probably a necessary part of the digestive system thousands of years ago and perhaps helped in cellulose digestion. The organ is believed to be gradually disappearing in human beings and is often referred to as a vestigial organ — those organs or parts now disappearing for being in disuse but ancestrally well developed.

               The appendix has muscular valves, ordinarily capable of expelling the mucus secretions of the appendiceal valves into the caecum. If anything blocks the opening, the continued secretion and the bacteria within the organ build up pressure. It may also be invaded by germs. This causes the whole area to become sore and swollen. The painful inflammation of the appendix is medically termed as appendicitis. A person experiencing an attack of appendicitis may feel abdominal pain in the right lower region of the abdomen. He may feel nausea or have diarrhoea. There can also be slight fever unless the appendix bursts. Recurrent mild attacks of appendicities in children are often diagnosed as ‘bilious attack or disorder of biles’. The only safe plan is to watch such cases very carefully and immediate attention should be given for proper treatments.

               In acute cases, surgical operation is needed. It is operated on after giving general anaesthesia. The appendicitis is caused usually when bits of undigested food stick in the opening to the appendix and block it. This gives bacteria a warm, closed place where they can grow and multiply and produce a painful swelling. 

               We are all familiar with the itching sensation and scratching gives us some relief. But what causes it and why scratching gives a soothing sensation?

               When the pain nerves in our skin are stimulated a little, we do not feel pain but feel a tickling sensation in our skin, which causes a desire to scratch. A mosquito bite irritates the pain nerves of our skin just enough to cause an itch. Dryness of the skin or wounds on the body surface and various allergies can also cause itching. Similarly many other diseases like kidney disorders and cancer can cause itching.

               The best way to deal with mosquito —bite itch is to scratch lightly in a circle all around, but not directly on the place of bite.

               Scratching the skin at one spot may help for a while but can produce an itch at some other places of the body. According to some doctors, the reason behind it is that the pain nerves in the area around an itch become more sensitive. Scratching stimulates these nerves just enough to start a new itch. So the feeling spreads.

               Now the question arises, why is the skin the only part of our body that can feel an itch? This is a big mystery. We have pain nerves inside our body also but we never feel an itch in the inner organs such as liver or heart. The medical scientists are still quite ignorant about the reasons.

               The police dogs can identify the criminals on the basis of smell of their bodies. This clearly proves that each of us has a special kind of body smell. On the basis of certain experiments it has been established that even the twins have slightly different smell. Dogs with some special training can even identify between the twins Do you know why everybody has a particular smell?

               The body smell depends upto some extent on an oily liquid secreted by sweat glands in the body. But the scent is mainly the product of bacteria that feed on sweat. When a child is born, he picks up many bacteria from the mother, and those who touch him. Their number in cases as the child comes into further contact with others. Within several days of the birth many kinds of bacteria settle down permanently on our skin all through our lives. The types of bacteria may differ from person to person and they produce different types of odour in different persons. That is why, different persons have different smell.

               The pancreas is an important organ found in the bodies of human beings and all animals with backbones. It lies crossways behind the stomach. This organ resembles a flask lying on its side. The human pancreas is a pinkish yellow gland about 12 to 15 cm long, 3.8 cm. wide and 2.5 cm. thick. It is joined to the small intestine behind the stomach. Do you know the function of the pancreas?

               The pancreas produces a strong digestive juice in the intestines that breaks down food particles for easy digest. It also produces the hormones, insulin and glycogen. It produces 1200 to 1500 ml. of pancreatic juice every day. This juice flows into the small intestine or duodenum. It contains enzymes and salts which help in digesting proteins, starches, sugars and fats. As the food enters the mouth, the taste buds send impulses to the brain. It stimulates the pancreas via vagus nerve to secrete its juice. The pancreatic juice is rich in sodium bicarbonate, which helps in neutralising the acid. 

               Pancreatic juice has five main enzymes. Three of these help in the digestion of proteins; the other two — amylase and lipase — digest carbohydrates and fats respectively. The main protein digesting enzyme is called trypsin.

               Apart from the digestive function the pancreas also produces the essential hormones insulin and glucagon from a group of cells known as islets of Langerhans. Glucagon converts glycogen to glucose by which the sugar level in the blood is maintained. Insulin decreases the blood sugar level when it is increased. Insulin is produced in the ‘tail’ part of the organ and deficiency of this hormone causes diseases like diabetes. In such cases diet of the patient should be rich in protein, low in fat and plenty of pure water be taken. This hormone converts glucose to glycogen inside the liver. These two hormones working together control the energy requirements of the body. 

               There are over 600 muscles arranged around the frame of a human skeleton and inside the body. These muscles are responsible for various movements of the body. When these muscles are active, as happens in the case of muscle contraction and stimulation, they produce electric impulses. Electromyogram or EMG is a record of such impulses.

               Electromyogram provides valuable information regarding the disorders of the muscles. The electric signals from the muscles are obtained during voluntary contraction. For this purpose, an instrument is used whose electrodes are connected to the particular muscle. These electrodes carry the electrical impulses through the wires to a pen recorder which marks these in the form of a graph on a paper.

               Now the question arises, how do muscles produce electric impulses? A muscle is made up of many motor units. A motor unit consists of a single branching neuron from the spinal cord to the muscle fibres. This gives rise to a potential difference. In fact, this potential difference is recorded in the form of electromyogram.

               Single muscle cells are usually not monitored in an EMG examination because it is difficult to isolate a single fibre. Instead, EMG electrodes record the electric impulses from several fibres. EMG gives valuable diagnostic information about muscles. With the help of an EMG the contraction of a muscle can be known.

               EMG can also be recorded with electric stimulation. A typical stimulating pulse may have amplitude of 100V and lasts from 0.1 to 0.5 m-secs. With the help of an EMG we can study the reflex responses of the muscles and can know their working level. For instance our heart muscles go on pumping blood. If there is any disorder in pumping system, the device can identify heart muscles which may not be in its normal state. The major muscles in humans can be stimulated at a rate between 5 and 15 hertz. Normal nerves and muscles show some changes during prolonged restimulation. On the basis of EMG we can gather information about any malfunctioning of the muscles.