Science Glossary (N-S)

n-telopeptide - ??
NAD synthetase
NAD synthetase is a key enzyme in the formation nicotinamide adenine dinucleotide (NAD) biosynthesis. NAD serves as a respiratory enzyme that alternates between oxidation and reduction states with the hydrogen atom. NAD synthetase is target for structure based design of antibiotics.
NASA-Mir program
Natural killer cell (NK cell)
A natural killer cell is a specific type of lymphocyte (white blood cell) which kills 'target" (tumor or virus-infected) cells without involving antibodies. The mechanism of their killing activity is not yet clear, but interferon seems to play a role.
Neural means pertaining to the nervous system.
Neuraminidase is an enzyme that cleaves terminal acylneuraminic residues from oligosaccharides, glycoproteins, or glycolipids; present as a surface antigen in myxoviruses. It is also used in histochemistry to selectively remove sialomucins as from bronchial mucous glands and the small intestine.
Neuroendocrine system
The neuroendocrine system is a system of dual control of certain activities of the body by means of both nerves (neuro-) and circulating hormones (endocrine).
Neurovestibular relates to the interaction between the brain and the vestibular organ, which is located in the inner ear.
Neutron diffraction
Neutron diffraction is a method used to determine the molecular structure of a material by passing a neutron beam through the sample and capturing the diffraction pattern.
Nickel is a silver-white hard malleable ductile metallic element capable of a high polish and resistant to corrosion. It is used chiefly in alloys and as a catalyst.
Nitrogen-15 isotope
The nitrogen-15 isotope is a biological tracer that can be used to measure protein metabolism in urine and saliva.
Nucleic acid
Nucleic acid is either of two organic acids, DNA or RNA, present in the nucleus and in some cases the cytoplasm of all living cells. Their main functions are in heredity and protein synthesis.
Nucleosome core particle
Nucleosome core particle is a localized aggregation histone and DNA that is evident when chromatin is in the uncondensed stage.
Nutational is the oscillatory movement of the axis of a rotating body; wobble.

Oligonucleotide is a compound made up of the condensation of a small number of nucleotides.
Optic tectum - ??
Optical means pertaining to or using light; it also describes something designed to assist sight.
Organic means of or originating from carbon compounds.
Organogenesis is the formation of organs during development.
Orthostatic relates to the upright position of the body; the term is used when describing this position or a condition caused by it. Orthostatic hypotension, for example, is low blood pressure found in some people when they stand upright.
Orthostatic hypotension
Orthostatic hypotension is a temporary and short-lived condition of low blood pressure, sometimes occurring when a person stands or sits upright from a sitting or recumbent position; it can result in light-headedness or fainting.
Orthostatic intolerance
Orthostatic intolerance is a condition of lightheadedness, possibly leading to fainting, that occurs when an upright position is assumed; it is caused by low blood pressure and an inadequate supply of blood to the brain. Astronauts often experience temporary orthostatic intolerance when remaining upright after returning from stays in space, because their blood volume is reduced in microgravity and the pull of gravity does not allow sufficient blood flow to reach their heads.
An oscillation, as it applies to microgravity experiments, is a vibration. However, oscillations can refer to any steady back and forth movements.
Osteocalcin is a bone matrix protein consisting of 49 amino acids.
Osteoporosis is the loss of bony tissue, resulting in bones that become brittle and liable to fracture. Infection, injury and synovitis (inflammation of the membrane surrounding a joint), as well as prolonged exposure to microgravity, can cause osteoporosis.
Ova are female gametes; eggs.
Oxalate is a salt of oxalic acid, an acid found in many plants and vegetables.
Oxygen consumption
Oxygen consumption is the amount of oxygen in milliliters per minute required by the body for normal aerobic metabolism; normally about 250 ml/ minute.

Parathyroid Hormone (PTH)
Parathyroid hormone (a.k.a. parathormone, PTH) is a hormone, synthesized and released by the parathyroid glands, that controls the distribution of calcium and phosphate in the body.
Passive payload
A passive payload on the Space Shuttle, or other space vehicle, does not require any crew time or astronaut interaction to operate, except possibly for the need to be activated, placed in a certain position or shut down.
Pathogenic means causing disease or abnormality.
Pathology is the study of disease processes with the aim of understanding their nature and causes. This is achieved by observing samples of blood, urine, feces, and diseased tissue obtained from the living patient or from an autopsy, by the use of X-rays and by many other techniques.
Pathophysiological pertains to the study of biologic and physical manifestations of disease as they correlate with the underlying abnormalities and physiologic disturbances.
Personal Computer Memory Card Interface Adapter
Peak oxygen consumption
Peak oxygen consumption refers to the highest value of oxygen consumption measured during an exercise period.
PEP carboxykinase
PEP carboxykinase is an enzyme of the lyase class that catalyzes the conversion of ATP/GTP and oxaloacetate to ADP/GDP, phosphoenolpyruvate, and carbon dioxide.
Perfusion is the passage of fluid through a tissue. It can refer to the passage of blood through the lung tissue to pick up oxygen from the air in the alveoli and the release of carbon dioxide. Or, perfusion can refer to the deliberate introduction of fluid into a tissue, usually by injection into the blood vessels supplying the tissue.
A perturbation is a disturbance or abnormality.
pH indicates the acidity of a substance. A pH below 7 is acid, a pH above 7 is alkaline and a pH of 7 is neutral.
Pharmacodynamics is the study of drug action on living organisms.
Pharmacokinetics refers to the study of the metabolism and action of drugs, with particular emphasis on the time required for absorption, duration of action, distribution in the body, and excretion.
Pharmacologic means pertaining to the science of drugs, including their composition, uses and effects.
Pharmaceutical refers to man-made and natural drugs used to treat diseases, disorders, and illnesses.
Phenol is a highly poisonous, caustic crystalline chemical compound derived from coal tar or plant tar or manufactured synthetically. It has a distinctive, pungent odor and, in solution, is a powerful disinfectant.
A phenotype is the visible properties of an organism that are produced by the interaction of the genes and the environment.
Phosphate (PO4)
Phosphate is a salt of phosphoric acid. Phosphates are extremely important in living cells, particularly in the storage and use of energy and the transmission of genetic information within a cell and from one cell to another.
A phospholipid is a lipid (fat) containing phosphorus.
Photosynthesis is the process by which green plants use the energy of light and a special substance called chlorophyll to synthesize carbohydrates (energy) from carbon dioxide and water.
Physiological means of or relating to physiology.
Physiology is the study of the functions or vital processes of living things, whether animal or plant.
A pivot is a short rod or shaft about which a related part rotates or swings.
Plasma Volume (PV)
Plasma volume is the measure of volume of plasma in the blood. Plasma is the liquid portion of blood consisting of various inorganic salts, such as sodium, potassium, calcium, and proteins; the solid portion of blood is composed of cells. Normal plasma volume in an average adult is usually 3 liters, while total blood volume is about 5 liters.
A platelet is a disk-shaped structure present in the blood; they have several functions, all relating to stopping bleeding.
Pneumococcal refers to Pneumococcus, which is another name for Streptococcus pneumoniae; a species of Gram-positive, lancet-shaped diplococci frequently occurring in chains; cells are readily lysed by bile salts. Virulent forms are enclosed in type-specific polysaccharide capsules; there is also a specific somatic antigen (M protein) for each of the approximately 85 types, and somatic C carbohydrate common to all types. They are normal inhabitants of the respiratory tract, and are perhaps the most common causative agents of meningitis, sinusitis, and other infections.
A polymer is a natural or synthetic compound of high molecular weight composed of long chains of repeating units, each relatively light and simple.
Polymerase Chain Reaction (PCR)
Polymerase Chain Reaction, or PCR, is a process which permits scientists to make unlimited copies of genes. This is done with a single molecule of DNA. One hundred billion copies of the DNA can be generated in a few hours. This technique is used to investigate and diagnose bacterial diseases, viruses associated with cancer, and genetic diseases such as diabetes mellitus.
A polypeptide is a molecular chain of amino acids.
Potable describes water that is fit to drink.
A primer is a short sequence (of RNA or DNA) from which DNA replication can initiate.
The Priroda module is the latest module added to the Mir Space Station. It docked with Mir during the Mir-21 mission, and is now configured as a laboratory where Earth observation and microgravity research is being conducted.
Promyelocytic leukemic cell
Promyelocytic leukemia cells are abnormal promyelocytes, with very heavy granulation obscuring the basophilic cytoplasm. Leukemia of the promyelocytic cells is classified as M3 leukemia, a form of Acute Myeloid Leukemia (AML).
Protein metabolism
Protein metabolism is the process of production, use, and excretion of protein in the human body. Proteins are essential chemical substances that the body uses in many processes, including energy production. Proteins form the structural material of muscle, tissue, organs, and when they make up enzymes and hormones, they also regulate the function and behavior of other cells.
Protein synthesis
Protein synthesis is the process of anabolic metabolism (simple substances converted into more complex compounds) that forms new proteins.
Proteinase K
Proteinase K (also known as Endopeptidase K) is an enzyme that catalyzes the hydrolysis of keratin and other proteins with subtilisin-like specificity; it also hydrolyses peptide amides. Endopeptidase K comes from the mold Tritirachium album Limber.
A provocative move is one which will induce, or cause, certain symptoms or effects.
Pseudomonal Protein A
Pseudomonal Protein A is antigen-protein associated with Pseudomonas, a genus of motile, polar flagellate, nonsporeforming, and strictly aerobic bacteria.
Pseudomonas is a genus of motile, polar flagellate, non-sporeforming, strictly aerobic bacteria containing straight or curved, but not helical, Gram-negative rods, which occur singly. The metabolism is respiratory, never fermentative. They occur commonly in soil and in fresh water and marine environments. Some species are plant pathogens. One species is a specialized mammalian parasite, while others are only occasionally pathogenic to animals.
Pseudomonas aeruginosa
Pseudomonas aeruginosa is a species of bacteria found in soil, water and clinical specimens; it is the causative agent of blue pus and is occasionally pathogenic for plants. P. aeruginosa usually causes infections in humans only when there is a defect in host defense mechanisms.
Pulsed-Field Gel Electrophoresis (PFGE)
Pulsed-field gel electrophoresis (PFGE) is a method used to separate high molecular weight linear DNA fragments that are greater than 50 kilobases (kb) in size. Fragments are separated by pulsing an electrical field across an agarose gel rather than applying the constant field used in conventional electrophoresis.
Purification is the act or process of cleansing.
A pushrod is a rod moved by a cam to operate the valves of a system.
Pyridium cross-link - ??

Quarantine is the enforced isolation or restriction of free movement imposed to prevent the spread a contagious disease.

Rapid Eye Movement (REM)
Rapid Eye Movement (REM) is the sleep stage during which the muscles of the eyeballs are in constant motion behind the eyeballs. This is the phase in which dreaming is thought to occur.
Red blood cell mass
Red blood cell mass is the amount of red blood cells in the body.
Red Blood Cell (RBC)
A red blood cell (RBC) contains the pigment hemoglobin, which has the principle role of the transport of oxygen.
Reflectance is the ratio of the total radiant flux, as of light, reflected by a surface to the total striking the surface.
A reflectometer is an instrument used to measure the reflectance of a surface.
Remote sensing
Remote sensing is the ability to measure, observe or study something distant through the use of special instruments, devices or electronics, such as the use of satellites to study crop growth.
Renal stone
A renal stone, or kidney stone, is a hard pebble-like mass commonly composed of calcium oxalate that forms within the kidney. Some kidney stones cause pain and must be removed from the body using surgery or ultrasound techniques.
Renal stone-forming salt
Renal stones are formed from the renal stone-forming salts calcium oxalate, calcium phosphate, uric acid, struvite and cystine. The most common substance making up renal stones is calcium oxalate, which makes up about 70% of all formed stones.
Respiratory rate
Respiratory rate is the rate of breathing (respiration) expressed as breaths per minute.
Resorption is the act of removal by physiological absorption.
Restriction Fragment Length Polymorphism (RFLP)
Restriction fragment length polymorphism (RFLP) is a variation in electrophoresis banding patterns of specific DNA fragments from different individuals of a species. RFLP is caused by the presence of a restriction enzyme cleavage site at one place in the genome of one individual and the absence of that specific site in another individual (a restriction enzyme recognizes a specific target nucleotide sequence in DNA and breaks the DNA chain at that target).
Retention is the process of holding back, or retaining. During the excretion of fluids from the body by the kidneys, electrolytes and other substances dissolved in urine are excreted, while retention of water occurs, producing a more concentrated urine.
RNAzol is bioseparation method used to extract RNA material from tissue homogenates or body fluids.

Scanning electron microscope
A scanning electron microscope is a microscope that forms a three-dimensional image on a cathode-ray tube by moving a beam of focused electrons across an object and reading both the electrons scattered by the object and the secondary electrons produced by it.
The scapula is the bone known as the shoulder blade.
Sclerenchyma is a plant tissue in which the cells have greatly thickened walls impregnated with lignin and no cell contents. The tissue has a mechanical function of supporting the plant and consists of two types of cells, fibers and scleroids. Fibers are long cells with tapered ends, which are often grouped into bundles.
Single Event Unit (SEU) is a single change in the binary code. SEUs can be caused by radiation.
Sintering means to heat a powdered substance without thoroughly melting it, causing it to fuse into a solid but porous mass.
Somatic refers to the non-productive parts of a body.
South Atlantic Anomaly (SAA)
The South Atlantic anomaly (SAA) is a region of intense radiation from protons trapped in the part of the Van Allen radiation belts lying closest to the earth's surface. The SAA arises primarily because the earth's magnetic field is offset from its center. Over this region, the geomagnetic field draws particles closer to the Earth than in other regions of the belts. The South Atlantic anomaly is located over a large portion of South America, the South Atlantic and the southern tip of Africa.
Space Motion Sickness (SMS)
Space motion sickness (SMS), or Space Adaptation Syndrome (SAS), is a syndrome experienced by space travelers that is similar to motion sickness on earth (air sickness, car sickness, sea sickness), causing nausea, dizziness and sometimes vomiting. Space motion sickness affects about 60% of the people who travel in space with varying degrees of severity.
Spectral means relating to or produced by a spectrum, the distribution of energy emitted by a radiant source.
Spin-spin relaxation time
Static Random Access Memory
Staphylococcus aureus
Staphylococcus aureus is a common bacterial species found on nasal mucous membranes and the skin (hair follicles). S. aureus causes pneumonia, endocarditis, and other infections, as well as food poisoning; it is also a main cause of infections in burn patients.
Star tracker
The Star Tracker is an electro-optical tracking device used while the Shuttle is in orbit to align it with other objects, as well as to track targets, such as the Mir. These functions support the docking of the Shuttle to the Mir.
Starch is a polysaccahride made up of glucose residues that exists in most plant tissues. It is also found in the human body in saliva and pancreatic juice. It is used as a dusting powder, an emollient and an ingredient in medicinal tablets and is an important raw material for the manufacture of alcohol, acetone, butanol, lactic acid, citric acid and glycerine.
Struvite takes the form of crystals of magnesium ammonium phosphate which are present in some renal stones (kidney stones).
Submaximal means less than maximum. Submaximal exercise requires less than one's maximum oxygen uptake, heart rate, or anaerobic power. Usually refers to intensity of the exercise, but may be used to refer to duration.
Submicron refers to any object measuring smaller than one micron, a unit equal to one-millionth of a meter.
Submicroscopic means too small to be seen in an ordinary light microscope.
A superconductor is based on the conduction of high levels of electrical current through a specially made material that is kept at very low temperatures. The low temperature keeps the conductor's resistance low to allow for increased current passage.
Supersaturation occurs when the level of a substance in urine exceeds the level of that substance due to food intake. Many nutritional components not needed by the human body are excreted by the kidneys in the urine.
Supine denotes the body while lying on the back, face upward.
Svet is the Russian word meaning light. It is also the name given to the Russian greenhouse, where plants are grown on the Mir station.
Sympathetic means relating to the actions of the sympathetic nervous system, one of the two divisions of the autonomic nervous system. Its nerves are distributed to the blood vessels, sweat glands, salivary glands, heart, lungs, intestines and other abdominal organs, and the genitals. Sympathetic stimulation causes excitatory effects in some organs but inhibitory effects in others.

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