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Medical Dictionary


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NARCOTIC - an agent which depresses the function of the central nervous system, inducing sleep and lessening pain. By definition, narcotics can be toxic in excess.

NECROSIS is the cellular death of individual, local or specific groups of cells.

NEOPLASIA - the process of tumor formation or a tumorous condition of the body.

NERVINE - A substance which quells nervousness and irritability, either through depression or stimulation of the central nervous system.

NEURITIS is an inflammation of a nerve or nerves, usually associated with a degenerative process. Marked by neuralgia, hyperesthesia, paresthesia, anesthesia, paralysis, wasting, and disappearance of the reflexes. Causes can be mechanical (compression, contusion, or trauma), vascular (as in neuritis accompanying peripheral vascular disease), or metabolic (such as thiamine deficiency, gastrointestinal dysfunction, diabetes, or toxemias related to pregnancy). Other factors include infections - direct, localized infections of nerves with accompanying diseases such as leprosy, tetany, tuberculosis, malaria, and measles - and toxins, especially poisoning by heavy metals such as arsenic, lead, and mercury, or by alcohol or carbon tetrachloride.

NEUROLOGIST: Twitch doctor.

NEUROTIC: Sane but unhappy about it.

NEUROTIC: A person who worries about things that didn’t happen in the past, instead of worry about something that won’t happen in the future, like normal people.

NITROGEN BALANCE is an estimate of the difference between nitrogen intake and output. The number is derived by subtracting the amount of urea nitrogen in a urine sample from an individual's total protein intake. If the urinary urea nitrogen value is larger than the protein intake, the nitrogen balance will be a negative number. A negative nitrogen balance indicates that not enough protein was ingested to meet the body's nutritional requirements, and that endogenous muscle protein has to be broken down to provide the nutrients for metabolic processes. Prolonged negative nitrogen balance results in muscle wasting and general weight loss. If the urinary urea nitrogen value is smaller than the protein intake, the nitrogen balance will be a positive number. This positive nitrogen balance results from ingesting dietary protein in amounts which meet the metabolic requirements of the body.

NOREPINEPHRINE - A hormone produced in the Adrenal Medulla which acts as a transmitter substance of the peripheral sympathetic nerve endings, and probably of certain synapses in the central nervous system. It constricts the arterioles and venules - (the very small arteries leading to capillaries and continuous tiny veins) to regulate increased resistance to blood flow, elevated blood pressure and slowing of the heart.

NUCLEIC ACIDS are a group of high molecular weight, polymeric substances including DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). DNA is the chemical basis of heredity and the carrier of genetic information of all organisms. RNA may also be the carrier of genetic information in some viruses. In other organisms it reacts with and carries an activated amino acid to participate in the manufacture of protein molecules.

Nucleic acids are found in the nuclei, nucleoli, mitochondria, and cytoplasm of all cells, and in viruses. Nucleic acids have complex chemical structures, formed of pentoses, phosphoric acid, and nitrogen bases prines and pyrimidines.

NUTRIENTS are foods or any substances which supply the body with elements necessary for metabolism. Certain nutrients (carbohydrates, fats, and proteins) provide energy; other nutrients (water, electrolytes, minerals, and vitamins) are essential to the metabolic process.

NURSE: Needlepoint expert.

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