Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «N»:
Nuchal: Referring to the back of the neck (nape). For example, nuchal rigidity is a stiff neck, sometimes a symptom of meningitis.
From the Latin "nucha" meaning nape. Pronounced "nu·kal" with the accent on the first syllable....
Nuchal translucency test
Nuchal translucency test: A measurement of the size of the translucent space behind the neck of the fetus using ultrasound at between 10 and 14 weeks of pregnancy, reflecting the amount of fluid that has accumulated under the skin of the fetus. Nuchal translucency tends to be increased in chromosome...
Nuclear family: The family group consisting of the father, mother, and their children, as distinct from the extended family....
Nuclear medicine: The branch of medicine concerned with the use of radioisotopes in the diagnosis, management, and treatment of disease. Nuclear medicine uses small amounts of radioactive materials or radiopharmaceuticals, substances that are attracted to specific organs, bones, or tissues. The radi...
Nuclei: The plural of nucleus....
Nuclei, basal: A region located at the base of the brain composed of 4 clusters of neurons, or nerve cells. This area of the brain is responsible for body movement and coordination.
The groups of neurons most prominently and consistently affected in Huntington disease -- the pallidum and striatum ...
Nucleic acid: One of the family of large molecules which includes deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Nucleic acids were so named because they were first found in the nucleus of cells, but they have since been discovered also to exist outside the nucleus.
The two chief types of...
Nucleic acid hybridization
Nucleic acid hybridization: A technique in which single-stranded nucleic acids (DNA or RNA) are allowed to interact so that complexes called hybrids are formed by molecules with similar, complementary sequences.
Through nucleic acid hybridization, the degree of sequence identity between nucleic aci...
Nucleic acids: See nucelic acid....
Nucleocapsid: The genome + the protein coat of a virus. The nucleic acid (RNA or DNA) of the virus is its genome. The protein coat is its capsid. See also: Capsid....
Nucleocaspid: The genome plus the protein coat of a viral. The genome is nucleic acid. The protein coat is the capsid. The term nucleocaspid was coined in 1963....
Nucleosome: Structure responsible in part for the compactness of
a chromosome. Each nucleosome consists of a sequence of DNA wrapped around a core of
histone (a type of protein). ...
Nucleotide: A subunit of DNA or RNA. To form a DNA or RNA molecule, thousands of nucleotides are joined in a long chain.
Each nucleotide is divided into three parts (with apologies to Caesar):
A nitrogenous base (A, G, T, or C in DNA; A, G, U, or C in RNA),
A phosphate molecule, and
A sugar molec...
Nucleus: 1) In cell biology, the structure that
houses the chromosomes. 2) In neuroanatomy, a group of nerve
Nucleus amygdalae: See: Amygdaloid nucleus....