Nervous system

The Nerve is an element of the central or peripheral nervous system that carries impulses from the brain or spinal cord to the eyes, ears, muscles, glands and other parts of the body. Nerves consist of bundles of fibers covered with a sheath of connective tissue and sometimes by a layer of fatty cells (myelin). Nerve impulses are transmitted by a weak electrical current that results from chemical changes taking place through the nerve wall. The final transmission from one nerve to another or from a nerve to another structure is carried out by a chemical reaction via substances known as neurotransmitters.

The main nerves are named according to the regions to which they branch off. There are 12 pairs of cranial nerves and 31 pairs of spinal nerves. The spinal nerves consist of 8 pairs of cervical nerves, 12 pairs of thoracic nerves, 5 pairs of lumber nerves, 5 pairs of sacral nerves and 1 pair of coccygeal nerves.

The Nervous system is a network of billions of interconnected nerve cells (neurons) that receive stimuli, coordinate this sensory information and cause the body to respond appropriately. The nervous system is comprised of 2 main divisions: the central nervous system (CNS) which consists of the brain and the spinal cord; and the peripheral nervous system (PNS) which consists of spinal nerves and cranial nerves that link the CNS with the body’s receptors and effectors. The receptors include sensory cells and sense organs whose function is to sense and respond to various types of stimulation. For example, eyes respond to light, ears respond to sound. The effectors are all of the parts of the body, such as muscles and glands that respond to nerve impulse instructions from CNS.

The CNS receives the information from the PNS and sends instructions to various parts of the body to respond to continually changing conditions. The brain is involved in the processes of thinking, learning, memory and intelligence.

The PNS spreads out from the brain and spinal cord all over the body. It carries information to and from the CNS.

The autonomic nervous system controls involuntary functions in the body. These functions include gland activity, intestinal movements, beating of the heart, sweating. Within the autonomic nervous system there are two divisions: the sympathetic and parasympathetic systems.

The sympathetic system prepares the body for action by increasing blood pressure and heart rate, increasing glucose production by the liver, reducing the secretion of saliva, causing the erection of hairs on the skin, dilating the pupils of the eyes. The parasympathetic nervous system calms down the body after the sympathetic nervous system has speeded up its responses. The effects of the parasympathetic system include constriction of the pupils, slowing of the heart rate, contraction of the bladder, increase in the rate of digestion, constriction of the air passages.

Infectious diseases

Infectious disease is an illness caused by the growth of disease-producing microorganisms in the body. Infectious diseases may be contagious. The course of infectious diseases is often marked by certain stages or periods. The stage during which the germs are developing in the body without characteristic manifestations is called the period of incubation. It is followed by the prodromal stage during which the initial symptoms appear. After that the stage of the fully developed disease and the stage of decline come.

Prodromal symptoms appear earlier than the characteristic features, and therefore it may be impossible to make a diagnosis in the initial stage of the disease.

Such infectious disease as scarlet fever may have a sudden onset; however in others, such as enteric fever, the onset may be gradual.

A sore throat, a running nose and cough may occur among the most characteristic local symptoms. A sore throat is particularly characteristic of such diseases as scarlet fever and diphtheria; cough occurs in case of whooping-cough or measles.

A rash is a clinical feature of many infectious diseases such as chicken-pox, smallpox. Special attention should be paid to the type of rash, its color and distribution, and whether it is associated with itching or not.

All infectious diseases are caused by specific microorganisms, which may be revealed by bacteriological tests: for example, typhoid bacilli are found in the blood, stools and sometimes in the urine in enteric fever; meningococci are found in the blood and cerebrospinal fluid in meningitis.

Only in certain individuals natural immunity to some infectious diseases may exist. An artificial immunity results from prophylactic vaccination.

Thanks to the scientific achievements of our medical research work such diseases as the plague, cholera, malaria and others have been stamped out in our country. Smallpox was the first infectious disease eradicated via vaccination.

Some infectious diseases occur most often in children under the age of 10.

Diphtheria is caused by bacterium that usually grows on the membranes of the nose and throat; it is now a rare disease because of wide-spread vaccination against it.

Chicken-pox produces an itchy blister-like rash.

Scarlet fever may develop after a sore throat or acute tonsillitis; it can be spread by contaminated food or by infected droplets in the air.

Mumps causes painful inflammation and swelling of the salivary glands.

Whooping cough is a disease of the respiratory tract.

Meningitis is inflammation of the membranes that cover the brain and the spinal cord.

Let’s take, for example, a very rare case of enteric fever. Person’s prodromal

symptoms may consist of the loss of appetite, dull headache and general malaise. His characteristic symptoms may be high temperature, diarrhea, slow pulse, a characteristic eruption on the abdomen, a coated tongue, and the patient may complain of thirst.

The course of proper treatment may consist of antibiotics, intravenous injections of glucose, heart drugs, a strict diet, and a bed regime.

After the course of treatment the patient’s temperature becomes normal, the tongue clears, the appetite improves, and the strength returns. However, the patient’s convalescence may be slow.

The doctors of the infection clinic must have a wonderful bedside manner and a hearty attitude to their patients to encourage and help them to recover.

Other infectious diseases are brucellosis, encephalitis, hepatitis, tuberculosis, typhoid fever, typhus, yellow fever, and others.

Additional Vocabulary

brucellosis		бруцеллёз
contagius		заразный
decline		упадок, снижение
encephalitis		энцефалит
eradicate		искоренять
germ		микроб
hepatitis		гепатит
incubation		инкубационный период
tonsillitis		тонзиллит
tuberculosis		туберкулёз
typhus		сыпной тиф