Medical
Glossary


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

N.
Narcolepsy

a disorder that causes excessive sleepiness during the day and frequent and uncontrollable episodes of falling asleep

Narcosis

a drug (or other chemical)-induced drowsiness or stupor

Narcotic

an addictive substance that blunts the senses; can cause confusion, stupor, coma, and death with increased dosages

Narcotic analgesics

a type of painkiller that blocks the transmission of pain signals in the brain; often cause tolerance (the need for higher amounts of the drug to produce the same effect) and drug dependence

Nasal septum

the section of the nose that divides the left and right nostrils; made of cartilage and bone and covered by a mucous membrane

Nasogastric tube

a thin, plastic tube that is inserted through the nose, down the oesophagus, and into the stomach; used to drain, wash, or take samples from the stomach, or to feed very sick patients who cannot eat

Nasopharynx

the passageway connecting the back of the nose to the top of the throat

Natural childbirth

a technique of giving birth that stresses relaxation techniques so that the use of pain-relieving drugs can be minimised; also called prepared childbirth

Natural desiccated thyroid (NDT)

Natural desiccated thyroid is sometimes known as ‘Armour thyroid’ or NDT. In the UK the NHS uses the synthetic thyroid replacement hormone, levothyroxine (or lT4) to treat hypothyroidism. However some practitioners believe that certain patients do not respond symptomatically to this approach and use NDT instead. This is actual thyroid tissue (usually acquired from pigs), which has been dried to a powder and contains natural T4 and T3.

Natural methods of family planning

methods of planning a family that focus on a woman's time of ovulation, either so that pregnancy can be avoided or conception is likely

Nausea

feeling the need to vomit

Nebulizer

an instrument that provides a drug in its misted form through a face mask; used for severe asthma attacks and for children who have asthma but cannot use an inhaler

Necrosis

the medical term for the death of tissue cells

Needle aspiration

the use of a thin, hollow needle and syringe to remove body fluid for examination

Needle biopsy

the use of a hollow, wide-diameter needle to remove a sample of tissue for examination

Neonate

a term used to describe a new-born infant from birth to 1 month of age

Neoplasm

another term for a tumour

Nephrectomy

the surgical removal of one or both kidneys

Nephritis

inflammation of one or both kidneys because of an infection, an abnormal immune system response, or a disorder of metabolism

Nephroblastoma

a fast-growing cancer of the kidneys that occurs most commonly in children under 4 years of age

Nephrolithotomy

surgical removal of a kidney stone

Nephrons

the tiny filtering units of the kidney

Nephrosclerosis

the replacement of normal kidney structures with scar tissue

Nephrostomy

the surgical placement of a tube into the kidney to drain urine

Nephrotic syndrome

symptoms that result from damage to the filtering units of the kidney

Nerve

a bundle of fibres that transmit electrical messages between the brain and areas of the body; these messages convey sensory or motor function information

Nerve block

the dulling of sensation in an area of the body by injecting a painkiller into or around a nerve leading to that section of the body

Nerve cell

the basic unit of the nervous system; transmits chemical messages throughout the body

Nerve compression

pressure on a nerve, which can cause nerve damage and muscle weakness

Neural tube

the tube located along the back of an embryo that later develops into the spinal cord and brain

Neural tube defects

problems in the development of the spinal cord and brain in an embryo, such as the failure of the spine to enclose the spinal cord (spina bifida) and the failure of the brain to develop (anaencephaly)

Neuralgia

pain along the course of a nerve caused by irritation or damage to the nerve

Neuritis

inflammation of a nerve, often characterised by pain, numbness, or tingling; also used to describe nerve damage and disease from causes other than inflammation

Neuroblastoma

a cancerous childhood tumour located in the adrenal glands or the sympathetic nervous system

Neurofibrillary tangles

abnormal spiral filaments on nerve cells in the brain; characteristic of Alzheimer disease

Neurofibromatosis

a condition in which connective tissue tumours occur on nerves in the skin

Neuroleptic

an antipsychotic drug

Neuroma

a noncancerous tumour occurring in nerve tissue

Neurone

another term for a nerve cell

Neuropathy

disease, inflammation, or damage to the nerves connecting the brain and spinal cord to the rest of the body

Neurosis

relatively mild emotional disorders (such as mild depression and phobias)

Neurotoxins

chemicals that attack and damage nerve cells

Neurotransmitters

chemicals that transfer messages from one nerve cell to another or from a nerve cell to a muscle cell

Neutrophil

a type of white blood cell

Nevus

a marking on the skin; can be present at birth (birthmark) or develop later (such as a mole)

New-born respiratory distress syndrome

a disorder in which premature babies lack surfactant, a substance that stops the lungs from collapsing

Niacin

a vitamin important in many chemical processes in the body; also known as vitamin B3

Night terrors

a form of nightmare causing abrupt awakening in terror; occurs mostly in children

Nitrates

a group of drugs that widen blood vessels; used to treat insufficient blood supply to the heart (angina pectoris) and reduced pumping efficiency of the heart (heart failure)

Nocturia

urination or a sleep-disturbing need to urinate during the night

Nocturnal emission

ejaculation of semen during sleep, which is normal in adolescent males; commonly called a wet dream

Node

a small, rounded tissue mass

Nodule

a small lump of tissue that is usually abnormal; can form under the skin or protrude

Non-Hodgkin's lymphoma

any cancer in lymphoid tissue (found mostly in the spleen and lymph glands) that is not Hodgkin's disease

Non-insulin-dependent diabetes

a type of diabetes mellitus that occurs mainly in those over 40 who are overweight; it is usually treated with diet changes and drugs that increase production of insulin by the pancreas (also known as type II diabetes mellitus)

Nondisjunction

an error that occurs during the division of sex chromosomes, causing either too much or too little genetic information to be placed in an egg or sperm when it is formed

Noninvasive

a term that is used to describe medical procedures that do not enter or penetrate the body; also refers to noncancerous tumours that do not spread to other sections of the body

Nonnarcotic analgesic

a drug that relieves pain by blocking the production of chemicals that stimulate pain-sensing nerves

Nonsteroidal anti-inflammatory drugs

a group of drugs that relieve pain and reduce inflammation

Norepinephrine

a hormone that regulates blood pressure by causing blood vessels to narrow and the heart to beat faster when blood pressure drops

Norwalk virus

a virus that causes acute gastro-enteritis

Nosocomial infection

an infection acquired in a hospital

NSAID

see Nonsteroidal anti-inflammatory drug

Nucleic acids

substances found in every living organism that provide the instructions for development; includes DNA and RNA

Nucleotide bases

molecules that form nucleic acids

Nucleus

the centre or most important point of an object

Numbness

the lack of sensation in a part of the body because of interruption of nerve impulses

Nurse-midwife

a registered nurse who specialises in the care of a mother and child during pregnancy, labour, and delivery

Nutrient

any substance that the body can use to maintain its health

Nystagmus

persistent, rapid, involuntary movement of the eyes

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