Medical Glossary: N

Narcotic

A substance that induces insensibility or stupor. In pharmacology narcotics usually refer to drugs dervied from synthetic or natural opiates that relieve the perception of pain, induce eurphoria or sleep or reduce mental ability.

Nasogastric Tube

Any tube that is passed through the nose to the stomach. The purpose can either be to relieve stomach gasses, secretions or food, to obtain a specimen for laboratory analysis or to deliver food or medication.

Natural Childbirth

The process of labor and delivery perfomed with minimal medical intervention. It is widely considered to be the safest and most satisfying way to give birth, both for the baby and the mother. The pregnancy must be suitable, with the mother both physically and emotionally strong. Often called prepared childbirth, the best known methods are the Bradley Method and the Lamaze Method.

Nembutal

One of a variety of tranquilizing drugs collectively known as barbiturates.

Neonatal

The period of a baby's life between birth and 28 days. It is the riskiest time for the newborn, with about 65% of all deaths that occur during the first year taking place during the neonatal period.

Neonatal Jaundice

A term used to describe the result of the broken down red blood cells converted into non-toxic substances in the liver from the hemoglobin. Newborns may have levels of pigment too high for the liver to convert.

Neonatal Intensive Care Unit

Part of a hospital that is dedicated to the care and attention of newborn infants that are seriously ill or premature. It contains a variety of specialized equipment and is staffed by a team of nurses and neonatologists who are specially trained in the pathophysiology of the newborn.

Nervous System

An intricate network of structures that runs extensively throughout the body and activates, coordinates and controls all functions of the body.

The nervous system consists of two parts, the central nervous system and the peripheral nervous system. The central nervous system is composed of the brain and the spinal cord. The peripheral nervous system includes the cranial nerves and spinal nerves.

Afferent fibers carry sensory impulses to the central nervous system. Efferent fibers carry motor impulses in the form of electrical energy from the central nervous system to the muscles and other organs.

Somatic fibers are those associated with the bones, muscles and the skin. Visceral fibers are those associated with the internal organs, blood vessels and mucus membrane. All of the functions are coordinated by a network of tiny structures including neurons, axons, dendrites and ganglia.

Neural Tube Defects

Any of a group of congenital malformations that involve the skull and the spinal column. Most commonly it involves the failure of the neural tube to close properly during embryonic development.

High levels of alphafetoprotein in the amniotic fluid can reveal potential problems prenatally, and the fetus can be scanned using ultrasound. Immediate surgical repair is required.

Neurons

The basic nerve cell of the body's nervous system. A neuron contains a nucleus within a cell body. They are classified according to direction in which they conduct impulses, and the number of processes they extend.

Sensory neurons transmit impulses to the spinal cord and brain. Motor neurons transmit impulses from the brain to the muscles and glandular tissue.

Neurons work according to electrochemical processes involving positively charged sodium and potassium ions and the changing electrical environment of the intracellular and extracellular fluid of the neuron itself.

NICU

Abbreviation of neonatal intensive care unit; part of a hospital that is dedicated to the care and attention of newborn infants that are seriously ill or premature. It contains a variety of specialized equipment and is staffed by a team of nurses and neonatologists who are specially trained in the pathophysiology of the newborn.

Nicotine

A toxic substance present in tobacco and commonly used as an insecticide in agriculture. Large amounts can cause salivation, nausea, vomiting, diarrhea, headache, vertigo, reduced heartbeat and possible paralysis of the respiratory muscles. Treatment includes taking a weak solution of potassium permanganate, followed by activated charcoal and administration of artificial respiration.

Nonstress Test

A test in which the fetal heart rate as well as its physical movements as felt by the mother are recorded in order to determine the health of the baby.

Notochord

A strip of mesodermal tissue that extends along the back of the developing embryo beneath the neural tube. The structure is replaced by the vertebrae as the baby develops.

Nuchal Scan

A specialized form of ultrasound scanning that permits an estimation of the risk of Down's Syndrome to be determined.

Nucleus

The center of a cell that is surrounded by the cell membrane and contains genetic information. The nucleus issues commands for growth and reproduction.

Nurse Midwife

A nurse who has received specialized training in the care of pregnant women and the delivery of babies.

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