action potential
-a nerve impulse that is generated by depolarization of the membrane to a threshold (firing) value

alveolar ventilation
-aeration of blood in the alveoli (terminal dilations of the bronchioli) of the lungs

acetylcholine
-a biogenic amine

adenosine
-an endogenous nucleotide that is a constituent of ribonucleic acid yielding adenine and ribose on hydrolysis; a potent neuromodulator that is distributed at almost all synapses

altricial
-anatomically and physiologically retarded in development at the time of birth as compared with "precocial" animals;

ambient temperature
-temperature of the environment

apnea
-absence of breathing

atonia
-the absence of muscle tone

Tone is the resistance of a muscle to passive elongation or stretch; it is due to the asynchronous, sustained firing of motoneurons;

atropine
-a competitive inhibitor of the actions of the neurotransmitter acetylcholine at the muscarinic receptors of effector sites, particularly those innervated by cholinergic nerves; parasympatholytic agent that produces relaxation of the smooth muscles in various organs

basal condition
-basic state essential for maintaining the fundamental vital activities of an organism

benzodiazepines
-a group of drugs used mainly in the treatment of anxiety including, among others, chlordiazepoxide (Librium), diazepam (Valium), and oxazepam (Serax)

biogenic amines
-amines produced by living organisms

biological clock
-the brain mechanisms that determine when periods of increased and decreased activity occur in various biological systems

brainstem
-the lower part of the brain; a collective term for the medulla oblongata, pons, and midbrain

The part of the neuraxis, located at the base of the brain, that connects the spinal cord with the rest of the brain; it is thought to contain the mechanisms that regulate sleep and waking behavior, especially REM sleep and wakefulness

catabolism
-degradative metabolism involving the release of energy resulting from the breakdown of complex materials within the organism

cataplexy
-a sudden dramatic decrease in muscle tone and loss of certain reflexes, usually precipitated by strong emotional expression or by the intention of making a sharp movement or by startle; a part of the tetrad of narcolepsy

cholinergic (nerve)
-liberating acetylcholine; a nerve that releases acetylcholine as its neurotransmitter when it is stimulated, e.g., all motor nerves of the somatic nervous system

complex partial seizures
-involve associative areas, notably the limbic system, and there is impaired consciousness which may be associated with affective changes, automatisms and amnesia. Partial seizures are seizures in which the first clinical changes indicate activation of an anatomical and/or functional system of neurons limited to a part of a single hemisphere

cosmos
-the extraterrestrial vastness, or the universe in contrast to the earth alone;

depolarization
-the reciprocal of hyperpolarization;

desynchronous
-(relative to brain waves) an EEG record which lacks regularity of frequency, thought to indicate a varying and variable pattern of firing of brain cells

diencephalon
-the part of the brain above the mesencephalon containing the thalamus, hypothalamus, and the geniculate bodies;

diurnal
-recurring every day

dopamine
-a major neurotransmitter in certain areas of the central nervous system, especially in the nigrostriatal tract; the immediate precursor of norepinephrine in the body; an alpha-adrenergic stimulant;

EEG-(electroencephalogram)
-a recording of differences in electrical activity between two regions of the brain, ordinarily recorded by means of electrodes applied to the scalp

EDS
-excessive daytime sleepiness

endotherm
-warm (not hot)-blooded;

entrain
-(synchronize); zeitgebers, i.e., indicators of time, they may be clocks, mealtimes, workperiods, position of the sun, etc.;

etiology
-the doctrine of causes, specifically of the causes of diseases; causation;

eukaryotic
-characterized as having a true nucleus

free-running period
-a sleep-wake cycle that is internally generated and not responsive to subtle 24-hour time cues associated with the solar day); it can be modified by factors such as the environmental light intensity and hormones

galvanic skin activity
-refers to a change in skin resistance

hepatic failure
-failure of the liver to carry out its functions;

histamine
-an active endogenous substance that functions as a local hormone; acts to modulate local circulation, to influence the process of inflammation, and to stimulate gastric acid secretions; it is present in the central nervous system, possibly acts as a neurotransmitter;

homeothermy; homeotherms
-"warm-blooded"; birds and mammals are homeothermic because their body temperature is, within limits, independent of the outside temperature

homeostatic mechanisms
-feedback mechanisms that preserve the stability of the internal environment of a normal organism despite the presence of influences capable of causing profound changes;

hypercapnia
-excess carbon dioxide in the blood which results in overstimulation of the respiratory center

hyperpolarization
-an increase in the relative negativity of the interior of a neuron with respect to the exterior

It may be produced either by an alteration in the charge held by the membrane capacitor or by the movement of ions across the membrane. Hyperpolarization is accompanied by a decrease in excitability.

hypersomnolence
-pathologically excessive drowsiness or sleepiness

hypoxia
-oxygen deficiency;

idiopathic
-arising spontaneously or from an obscure or unknown cause;

impotence
-sterility; sometimes observed as a lack of the ability to copulate with lower vertebrates;

insomnia
-a dissatisfaction with the quantity or quality of sleep

internal desynchronization
-occurs when the internal relationships between the numerous daily rhythms that compose the human circadian system are disrupted

jet lag
-circadian desynchronization and sleeplessness that occurs due to jet aircraft travel to destinations that are several time zones away from the site of origin

locus coeruleus
-a region (bluish in the fresh brain) in the lateral portion of the pons;

metabolic rate
-the total quantity of heat that is released per unit of time by the body; this value is expressed in terms of heat energy, i.e., calories

microsleep
-brief intrusions of EEG indications of sleep

midbrain
-(mesencephalon) part of the brainstem above the pons and below the diencephalon; forms the upper part and limit of the brainstem;

Minnesota Multiphasic Personality Inventory
-a test of personal and social adjustment based on a complex scaling of the answers to an elaborate series of true or false questions

Morpheus
-the Greek god of dreams

myoclonus
-a brief and involuntary contraction of one or several muscles which displaces a segment of a limb, a whole limb, or even the entire body in a jerk-like movement

night terrors
-a sleep pathology that usually starts with a piercing scream; there is sweating and rapid breathing, and an increase in heart rate;

narcolepsy
-a disease in which the afflicted individual periodically finds it impossible to stay awake during the daytime (cataplexy, sleep paralysis and hypnogogic hallucinations (q.v.) together with narcolepsy complete the tetrad of narcolepsy;

ninja
-assassin

nonreciprocal flaccid paralysis
-atonia in muscles that are both flexors and extensors;

noradrenergic
-i.e., norepinephrine;

ontogenetic
-refers to the complete developmental history of the individual organism;

pavor
-[L.] terror

peptide
-a secondary protein derivative characterized by a combination of two or more amino acids

polyneuropathies
-the general term denoting functional disturbances and/or pathological changes in the peripheral nervous system

polysomnography
-the simultaneous evaluation of multiple physiological parameters during sleep

pons
-the smallest part of the brainstem lying between the medulla oblongata and the mesencephalon

pons tegmentum
-the dorsal part of the pons;

postsynaptic inhibition
-inhibition of a cell that is produced by the liberation, from a presynaptic cell, of a neurotransmitter that produces a decrease in excitability

purines
-a heterocyclic compound not found in nature but synthesized by chemists

raphe nuclei
-a complex of nine narrow cellular clusters on the midline that extends through the length of the brainstem (containing serotonin)

reticular formation
-a diffuse system of nerve cell bodies and fibers in the brainstem which extends from the medulla oblongata to the thalamus

signs/symptoms
-any abnormality indicative of disease, discoverable by the physician upon examination of the patient; a sign is an objective symptom, a symptom is a subjective sign of a disease;

sleep cycle
-the regular alternation between NREM and REM sleep that characterizes any relatively lengthy and undisturbed period of mammalian sleep

A NREM period plus the following REM period equals one sleep cycle;

sleep stages
-subdivisions of the sleep states (q.v.)

solitary tract
-a bundle of nerve fibers consisting of afferent (sensory) input from the vagus, glossopharyngeal and facial nerves

somnambulism
-episodes of nocturnal walking during which the subject is asleep or at least incompletely awake;

soporific
-causing or tending to cause sleep; tending to dull awareness or alertness;

spindle
-a round stick with tapered ends used to form and twist the yarn in hand spinning; a typical wave-form seen in the EEG during NREM sleep; it is characterized by a burst of very regular oscillations at a frequency of from 12 to 14 cycles per second. Sleep spindles are observed most often during NREM Stage 2 sleep

suprachiasmatic nucleus
-a group of nerve cells located above the optic chiasm

stage
-a relatively precise, but arbitrary, subdivision in the course of a continuously progressing quantitative change in some variable; arbitrarily, but precisely defined

telencephalic
-structures contained in the cerebral hemispheres;

tumescence
-the readiness for sexual activity marked especially by vascular congestion of the sex organs; slightly more visibly prominent in males

*But if we did we would find a series of inaccurate definitions, e.g.: a state of torpid activity [wrong]; state of an animal during hibernation [wrong]; the natural periodic suspension of consciousness [wrong] during which the powers of the body are restored [partially right]; and a state marked by a diminution of feeling followed by tingling [true, but unrelated].