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- NADH and NAD or Nicotinamide
Adenine Dinucleotide
- NAD(H) (èn´â-dê¹) noun also known as coenzyme #1,
the coenzyme with a primary role in the creation of cellular energy (see ATP).
- NAD(H) a coenzyme, C21H27N7O14P2,
occurring in all living cells and utilized alternately as an oxidizing or reducing agent
in various metabolic processes.
- [From n(icotinamide) a(denine) d(inucleotide), one of
its chemical names.]
- NADH (èn´â-dê-âch¹) (noun) The reduced form of NAD. [NAD + H1.]
2
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- Necrosis
- ne·cro·sis (ne-kro¹sîs, nè-) noun plural ne·cro·ses
(-sêz´) neropathy Death of cells or tissues through injury or disease, especially
in a localized area of the body.
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- [Late Latin necrosis, a causing to die, killing, from Greek nekrosis,
death, from nekroun, to make dead, from nekros, corpse.]
- — ne·crot¹ic (-kròt¹îk) adjective
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- Neurochemical or neu·ro·chem·is·try
- neu´ro·chem¹i·cal or neu·ro·chem·is·try
(n¢r´o-kèm¹î-strê, ny¢r´-) noun The study of the chemical composition and
processes of the nervous system and the effects of chemicals on it. —
neu´ro·chem¹i·cal (-kel) adjective — neu´ro·chem¹ist noun
2
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- Neurotransmitter
- neurotransmitter, chemical that transmits information across the
junction (synapse) that separates one nerve cell (neuron) from another nerve cell or a
muscle. Neurotransmitters are stored in the nerve cell’s bulbous end (axon). When an
electrical impulse traveling along the nerve reaches the axon, the neurotransmitter is
released and travels across the synapse, either prompting or inhibiting continued
impulses. There are more than 300 known neurotransmitters, including the ENDORPHINS and
ACETYLCHOLINE. 1
- Noradrenaline
- norepinephrine (nôr´èp-e-nèf¹rîn) or noradrenaline,
the NEUROTRANSMITTER that mediates chemical communication in the sympathetic NERVOUS
SYSTEM. Like other neurotransmitters, it is released at synaptic nerve endings to transmit
the signal from a nerve cell to other cells. It is almost identical in structure to
EPINEPHRINE. The sympathetic nervous system functions in response to short-term stress
(the fight or flight response); hence norepinephrine and epinephrine increase the heart
rate as well as blood pressure, increase the rate of glycogen conversion for energy, and
relax bronchial smooth muscle to assist breathing. 1
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- Norepinephrine
- norepinephrine (nôr´èp-e-nèf¹rîn) See noradrenaline above 1
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- Obsessive-Compulsive Disorder
- obsessive-compulsive disorder, type of psychological disturbance marked by
persistent unwanted patterns of thought (obsession) coupled with repetitive, ritualistic
behavior designed to alleviate discomfort or dread (compulsion). The individual recognizes
the thoughts and rituals as unrealistic or even repugnant, but is still unable to control
them, as in the case of a person who has such recurring fears about germs that he must
wash his hands excessively throughout the day. Obsessive-compulsive personality
disorder is a separate disorder characterized by perfectionism and inflexibility that
interfere with a person's ability to finish a task 1
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- Osteoarthritis
- os·te·o·ar·thri·tis (òs´tê-o-är-thrì¹tîs) noun A form of
arthritis, occurring mainly in older persons, that is characterized by chronic
degeneration of the cartilage of the joints.
Also called degenerative joint disease 2.
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- Oxidation and Reduction
- oxidation and reduction, complementary chemical reactions
characterized by the loss or gain, respectively, of one or more electrons by an atom or
molecule. When an atom or a molecule combines, or forms a chemical bond, with oxygen, it
tends to give up electrons to the oxygen. Similarly, when it loses oxygen, it tends to
gain electrons. Oxidation is defined as any reaction involving a loss of electrons, and
reduction as any reaction involving the gain of electrons. The two processes, oxidation
and reduction, occur simultaneously and in chemically equivalent quantities; the number of
electrons lost by one substance is equaled by the number of electrons gained by another
substance. The substance losing electrons (undergoing oxidation) is said to be an electron
donor, or a reductant. Conversely, the substance gaining electrons (undergoing reduction)
is said to be an electron acceptor, or an oxidant. Common reductants (substances readily
oxidized) are the active METALS, CARBON, CARBON MONOXIDE, HYDROGEN, hydrogen sulfide, and
sulfurous acid. Common oxidants (substances readily reduced) include the HALOGENS, NITRIC
ACID, OXYGEN, OZONE, potassium permanganate, and potassium dichromate. See also ANTIOXIDANT. 1
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