Glossary

Health Terms beginning with "N"

Nailfold capillary test

A test based on the observation that small capillary beds on the hands and feet may be dilated or disappear early on in scleroderma patients. The test involves taking a microscopic look at skin from under the fingernail, to see if capillaries look normal.

Narcolepsy

A sleep disorder in which you fall asleep at inappropriate times and without warning despite a good night's sleep.

Narcotic

A morphine-like drug or opium derivative that in moderate doses dulls the senses, relieves pain and induces profound sleep, but in excessive doses causes stupor, coma, convulsions or death.

Nasal continuous positive airway pressure

A procedure to treat sleep apnea in which the patient wears a mask over the nose during sleep, and pressure from an air blower forces air through the nasal passages.

Nasal polyps

Growths in the nasal passages that can be surgically removed to treat sleep apnea.

Natural family planning

Also known as the "rhythm method." Aims to control conception through careful monitoring of the woman's body temperature and changes in her cervical mucus.

Nedocromil sodium

A nonsteroid type of inhaled medication, like cromolyn sodium, for long-term asthma control.

Needle aspiration

A needle is inserted into a cyst or other tissue to remove liquid or tissue for microscopic examination.

Negative or deficit schizophrenia

Someone with schizophrenia who is unable to experience any initiative, motivation, social interest, enjoyment or any type of emotional responsiveness.

Negative symptoms

These symptoms, as they relate to schizophrenia, reflect a loss of normal functions, such as withdrawing socially or losing interest in work and other pursuits.

Neglect

The lack of providing adequate food, clothing and shelter to a child or some other person who can't care for themselves. An often overlooked form of abuse.

Nephrolithiasis

Kidney stones.

Nephrologist

A health care professional who treats patients with kidney problems or hypertension.

Nephron

A tiny part of the kidneys. Each kidney is made up of about 1 million nephrons, which are the working units of the kidneys, removing wastes and extra fluids from the blood.

Nephropathy

Disease of the kidneys caused by damage to the small blood vessels or to the units in the kidneys that clean the blood. People who have had diabetes for a long time may have kidney damage.

Nephrotic syndrome

A collection of symptoms that indicate kidney damage. Symptoms include high levels of protein in the urine, lack of protein in the blood, and high blood cholesterol.

Nervous system

The system of nerves and nerve centers in your body. A network of specialized tissue that controls actions and reactions and sensations of the body.

Neuraminidase inhibitors (NAI)

New antivirals that attack the virus at the cellular level by targeting and inhibiting the activity of one of the surface structures of the flu virus. Because it attacks a part of the virus that is the same in both types A and B, it's useful in treating influenza caused by either type of virus.

Neurocognitive

Having to do with the ability to think and reason, including the ability to concentrate, remember things, process information, learn, speak and understand.

Neuroendocrine cells

Cells that produce hormones.

Neurofibrillary tangles

Twisted fibers within nerve cells.

Neurofibromatoses

Genetic disorders of the nervous system that primarily affect the development and growth of neural (nerve) cell tissues. These disorders cause tumors to grow on nerves and produce other abnormalities such as skin changes and bone deformities. Scientists have classified the disorders as neurofibromatosis type 1 (NF1) and neurofibromatosis type 2 (NF2). The NF1 gene is on chromosome 17, while the NF2 gene is on chromosome 22. It is often the result of a new mutation in the affected person.

Neurogenic bladder

Loss of bladder control caused by damage to the nerves controlling the bladder.

Neurohormones

Chemical substances made by tissue in your nervous system that can change the structure or function or direct the activity of an organ or organs.

Neurological

Refers to your body's nervous system.

Neurologist

A doctor who works with disorders of the brain and nervous system. Although they can diagnose neurologic disorders and prescribe medications, they do not usually provide therapy for emotional aspects of these disorders.

Neuromodulation

Electrical stimulation of a peripheral nerve, the spinal cord, or the brain for relief of pain.

Neuromuscular

Relating to the nerves and muscles.

Neuron

The main functional cell of the brain and nervous system, consisting of a cell body, an axon and dendrites.

Neuropathic pain

Constant or recurrent pain that may last indefinitely. May not have an obvious cause and may be disabling, affecting daily life. Persistent neuropathic pain can cause fatigue, concentration problems and appetite changes and lead to suppression of the immune system, depression, anxiety and even suicide.

Neuropathy

Disease of the nervous system. Many people who have had diabetes for a while have nerve damage. The three major forms of nerve damage are peripheral neuropathy, autonomic neuropathy and mononeuropathy. The most common form is peripheral neuropathy, which mainly affects the feet and legs.

Neuroprotective agents

Medications intended to help limit the damage suffered by a nerve or neural tissue such as brain, nerve or spinal cord when the blood supply is cut off or there is a traumatic injury.

Neurosis

A long-term disorder featuring anxiety and/or exaggerated behavior dedicated to avoiding anxiety.

Neurotherapy

Also called EEG biofeedback or neurofeedback. This form of biofeedback trains you to recognize and alter your brain waves.

Neurotransmitter

A chemical substance released by nerve cell endings to transmit impulses across the space between nerve cells, tissues, or organs. In the brain neurotransmitters such as serotonin, dopamine and norepinephrine affect mood.

Niacin

See nicotinic acid.

Nicotine

The chief active and addictive compound in tobacco.

Nicotinic acid

Also known as niacin, it lowers total cholesterol, LDL-cholesterol and triglyceride levels, while raising HDL-cholesterol levels. While nicotinic acid is available without a prescription, it is very important to use it only under a health care professional's care because of possibly serious side effects.

Nitrates

These drugs, including nitroglycerin, relax blood vessels and alleviate chest pain. They are often prescribed for angina.

Nociceptors

Pain-sensitive receptors in the brain.

Nocicpetive pain

A signal to the body that it's being damaged in some way that needs immediate attention. Usually lasts for a short period of time and can be treated with rest and over-the-counter medication. Toothaches, sprains, backaches or a broken bone are common sources of nociceptive pain. Nociceptive pain can be persistent.

Nodule

A lump or localized growth on the thyroid gland.

Nonalcoholic fatty liver disease (NAFLD)

A buildup of fat within the liver that may lead to cirrhosis or other liver conditions. It is particularly prevalent in people who are overweight and in women.

Nonmelanoma skin cancer (NMSC)

A type of skin cancer that does not involve melanocytes, the cells that contain and produce the pigment called melanin. Basal cell cancer and squamous cell cancer are NMSC.

Non-rapid eye movement sleep

The sleep state that occurs when you first fall asleep and your brain waves become slower and less regular.

Nonsteroidal anti-inflammatory drugs (NSAIDs)

A group of medications, including aspirin, ibuprofen and related drugs, used to reduce inflammation that causes joint pain, stiffness and swelling.

Norepinephrine

A hormone produced by the adrenal gland that also acts as a neurotransmitter. Norepinephrine is found in areas of the brain that govern the automatic nervous system and is crucial in the fight-or-flight response.

Normal-tension

A form of glaucoma in which intraocular eye pressure is within the normal range, but the optic nerve deteriorates.

NSAID

Nonsteroidal anti-inflammatory drugs are a group of medications, including aspirin, ibuprofen and related drugs, used to reduce inflammation that causes joint pain, stiffness and swelling.

Nuclear scan

A test of the structure, blood flow and function of the kidneys. The health care professional injects a mildly radioactive solution into an arm vein and uses x-rays to monitor its progress through the kidneys.

Nuclear scanning

A test that is sometimes used to show damaged areas of the heart and areas of the heart muscle with decreased blood flow (ischemia) but no permanent damage. A small amount of a radioactive substance is injected into a vein, usually in the arm. A scanning camera records the nuclear material that is taken up by heart muscle (healthy areas) or not taken up (damaged areas). An initial test is recorded while resting; a second test is recorded while the patient is performing near maximum intensity on the treadmill. After approximately 30 seconds, a scan of the heart muscle is taken, showing areas of decreased blood supply.

Nurse anesthetist

A certified registered nurse anesthetist (CRNA) is allowed to administer and monitor anesthesia if he or she is under the supervision of an anesthesiologist.

Nutritionist

A health care professional primarily concerned with the prevention and treatment of illnesses through proper dietary care. Dietitians and nutritionists evaluate the diets of clients suffering from medical disorders and suggest ways of fighting health problems by modifying the intake of certain food items. They usually have a bachelor's degree with a major in dietetics, food and nutrition, or a related subject.