Glossary

This glossary was developed by Karen Borski and Kay Hoffman of the NASA Johnson Space Center.

A

Accelerometer: An accelerometer is a device which can measure acceleration, the rate of change of velocity with respect to time.
Acini: Acini are the small gas exchange regions of the lung.
ACTH: Adrenocorticotropic hormone (ACTH) is a hormone synthesized and secreted by the anterior pituitary gland that causes growth of almost all cells and tissues of the body, large amounts of which are secreted in response to any form of stress.
Adductor longus: The adductor longus is a superficial muscle of the upper leg, anterior surface. It is the thigh muscle that adducts, flexes and rotates the thigh medially.
Adenovirus: An adenovirus is one of a group of Deoxyribonucleic Acid (DNA) containing viruses causing latent infections of the upper respiratory tract that produce symptoms resembling those of the common cold.
Adrenal Cortex: refers to the outer region of the adrenal gland. ***
Adrenalectomize: A procedure removing the adrenal glands. ***
Aerobic: Aerobic means requiring free oxygen for life. Aerobic can also describe a type of cellular respiration in which foodstuffs (carbohydrates) are completely oxidized by atmospheric oxygen with the production of maximum chemical energy from the foodstuffs.
AEM: Animal Enclosure Module. ***
Albumin: Albumin is a type of simple protein widely distributed throughout the tissues and fluids of plants and animals and is characterized by being soluble by water and coagulable by heat.
Aldosterone: Aldosterone is the principle electrolyte-regulating steroid secreted by the adrenal cortex; it facilitates potassium exchange for sodium in the distal renal tubule, causing sodium reabsorption and potassium and hydrogen loss.
Alkaline Phosphatase: Alkaline phosphatase is present throughout the body, but is localized cytochemically in membranes. It liberates inorganic phosphate from phosphoric esters and serves as an indicator of the rate of bone formation.
Alloy: An alloy is a macroscopically homogeneous mixture or solid solution, usually of two or more metals.
Ambient: Room temperature.
Amyotrophy: Muscular wasting or atrophy.
Anemia: Any condition in which the number of red blood cells is less than normal, therefore reducing the oxygen-carrying capability of the blood.
Angiotensin I: Angiotensin is a family of vasoconstrictor substances present in the blood, and formed by the action of renin on a globulin of the blood plasma. Angiotensin I, a precursor of the physiologically active angiotensin II, is a decapeptide released when the enzyme renin splits a plasma protein called renin substrate.
Anode: An anode has a negative electrical load; all positive loaded ions move towards the anode.
Antibodies: Substances that are evoked in man or animal as a result of a stimulus provided by introduction of an antigen into the body.
Antidiuretic Hormone (ADH): Antidiuretic Hormone (ADH) is a hormone (also called vasopressin) produced and released in the posterior pituitary gland which causes the kidneys to retain water, thus increasing the water content of the body; also, in high concentrations, causes the constriction of blood vessels throughout the body and consequent elevation of blood pressure.
Antigen: Any substance that, as a result of coming in contact with appropriate tissues of a human or animal, induces a state of sensitivity. (Also called allergen or immunogen).
Antigravity muscles: Antigravity muscles are the muscles that pull against the force of gravity to maintain the normal upright posture.
Antioxidant: An antioxidant is a substance that prevents oxidation, and is commonly added to prepared foods, vegetable oils and paints to prevent deterioration when exposed to oxygen.
Antipyrine: Antipyrine is a substance used to reduce fever.
Aorta: The aorta is the main artery of the body from which all others derive; it arises from the left ventricle, arches over the top of the heart and descends in front of the backbone, giving off large and small branches and finally dividing to form the right and left iliac arteries.
Atmosphere: The atmosphere is the gaseous envelope surrounding a celestial body, especially that surrounding the Earth, which is retained in place by the force of gravity.
Atrial Natriuretic Peptide: Atrial natriuretic peptide(ANP) is a hormone-like substance present in large numbers of cells in the walls of the two atria of the heart, especially numerous in the right atria. This factor causes a three to ten times increase in renal excretion of sodium when it is released into the circulating blood. Consequent to the loss of sodium is a slight decrease in the extracellular fluid volume and blood volume. Although its exact mechanism of action is unclear, it is believed that the atrial natriuretic peptide plays a role in the regulation of blood volume.
Atrophy: Atrophy is the wasting away of a normally developed organ or tissue due to degeneration of cells. This may occur through undernourishment, disuse, or aging. For example, muscle atrophy is the condition resulting from reduced muscle mass which is due to disuse of the muscles.
Attenuation: Reduction of the disease-producing ability (virulence) of bacterium or virus by chemical treatment, heating, drying, by growing under adverse conditions, or by passing through another organism.
Audible: Audible means a noise or sound which is capable of being heard.
Autonomic Nervous System: Nervous system responsible for the control of bodily functions that are not consciously directed, including regular beating of the heart, intestinal movements, sweating, salivation, etc.
Axisymmetrical: Refers to like, or same, conditions on both sides of a body.

B

Bacillus: A large genus of gram-positive, spore-bearing, rod-like bacteria. They are widely distributed in soil and air (usually as spores). Most feed on dead organic material and are responsible for food spoilage.
Baroreceptor: A type of nervous system receptor found in the heart and large blood vessels (vena cava, aortic arch, carotid arteries). This receptor is sensitive to the stretching of the walls of these vessels that occurs when the blood pressure in the vessels increases.
Baroreflex: The reflex triggered by stimulation of a baroreceptor; if the baroreceptor detects that the blood pressure is too high, there is a baroreflex to reduce that pressure.
Baseline: A measurement which serves as a basis which all following measurements are compared to. An example: before exercise, your heart rate is measured. During exercise, your increased heart rate is measured and compared to your resting baseline measurement taken before exercise started.
Biochemical: Relating to the chemistry of living organisms and the changes that occur.
Biochemistry: Biochemistry is the study of the chemical processes and substances occurring in living things.
Biomass: The amount of living matter or organisms in a given volume or area.
Biomechanics: The science concerned with the action of forces, internal or external, on the living body.
Biopsy: A biopsy is the process of removing tissue from living patients for diagnostic examination.
Biosphere: The biosphere is the system of plants, animals and other living organisms along with the atmospheric, chemical and geologic processes which support life; it envelopes and depends upon the Earth.
Biotechnology: Technology dealing with living organisms.
Bone Density: Bone density is the mass per unit volume of bone under specified conditions of pressure and temperature.
Brachialis: Brachialis is a muscle that is situated at the front of the upper arm and contracts to flex the forearm; it works against the triceps brachii.

C

Calcitonin: A hormone produced by the parathyroid, thyroid and thymus glands and responsible for increasing the amount of calcium and phosphate deposited on bones.
Calcium: A metallic element essential for the normal development and functioning of the body, typically present in the blood at a concentration of about 10mg/100ml. Calcium is an important constituent of bones and teeth, and it is essential for many metabolic processes, including nerve function, muscle contraction, and blood clotting.
Calcium/bone homeostatic system: Calcium/bone homeostatic system is another term for the process of calcium balance, which is a measure of the intake and output of calcium from the body as measured in blood. Higher than normal levels of calcium in the blood (hypercalcemia) may be an indication of many things, including an abnormal loss of bone density. Demineralization is the term used to describe the breakdown of bone minerals, including calcium, during conditions of bed rest or disuse of bones, such as in weightlessness, and in medical conditions like osteoporosis.
Capillary: An extremely narrow blood vessel which forms a network to supply blood to the tissues of the body.
Carbon monoxide: A colorless, odorless and poisonous gas formed by the incomplete combustion of carbon. Its toxic action is due to its strong ability to bond with red blood cells and thus block the binding site for oxygen, thus reducing the ability for the blood to transport oxygen in the body. Its chemical symbol is CO.
Cardiac: Of, relating to, situated near, or acting on the heart.
Cardiac Output: Cardiac output is the amount of blood pumped by the heart in a unit period of time. The overall blood flow in the circulation of an adult person at rest is about 5000 ml per minute.
Cardiopulmonary: Of or relating to the heart and lungs.
Cardiovascular: Of, relating to, or involving the heart and blood vessels.
Cardiovascular deconditioning: A state in which the cardiovascular system does not work as efficiently as it can, usually caused by a change of environment, such as long periods of bed rest or in space travel.
Carotid: The carotid artery is either of the two main arteries in the neck whose branches supply the head and neck.
Catabolism: The chemical decomposition of complex substances by the body to form simpler ones, accompanied by the release of energy. The substances broken down include nutrients in food (carbohydrates, proteins, etc.), as well as the body's storage products (such as glycogen).
Cathode: A cathode has a positive electrical load; all negative loaded ions move towards the cathode.
Cell-mediated Immunity: Delayed hypersensitivity to an antigen, such as a positive response 24 to 48 hours after a tuberculosis test, as opposed to an immediate response to an antigen (humoral immunity).
Central Venous Pressure: Central venous pressure is the pressure in the right atrium of the heart (normally 0 mm Hg); it is regulated by the ability of the heart to pump blood out of the right atrium and the tendency for blood to flow from the peripheral vessels back into the heart.
Cervical: Of or relating to the neck.
Chloride: Chloride is a compound containing chlorine, especially salts of hydrochloric acid.
Chromosomes: Chromosomes contain DNA, which transmits genetic information. They are located in the nucleus of both plant and animal cells. In humans there are 46 chromosomes.
Chronic pulse/action relation: For any contraction of a muscle, a pulse, from a source such as the brain, must be generated. A specific delay between pulse generation and muscle action depends on various factors such as age, overall health, condition, mood, etc.
Circadian: Being, having, characterized by, or occurring in approximately 24 hour periods or cycles; in relation to sleep cycles.
Circulation: Circulation refers to the cardiovascular system of the body in which the heart together with two networks of blood vessels facilitate the movement of blood throughout the body bringing about transport of nutrients and oxygen to the tissues and the removal of waste products.
Citrate: A citrate is a compound of citric acid and a base; in the body it is involved in blood coagulation and the synthesis of fatty acids.
Cognitive: Cognitive refers to the mental process by which knowledge is acquired and used.
Combustion: The act or process of burning.
Contractile: Contractile means having the property of contracting, or becoming shorter in length or size.
Concentric: Concentric means muscle movement that shortens the muscle.
Convection: Transfer of heat by the circulation or movement by the heated parts of the liquid or gas.
Cortisol: Cortisol (hydrocortisone) is a steroid hormone synthesized and released by the human adrenal cortex; it is important for normal carbohydrate metabolism and response to any stress.
Countermeasure: A countermeasure is a measure or action taken in opposition to another; in space flight, several countermeasures are used to counteract negative effects of space flight, such as rigorous exercise regimens meant to keep the muscles and bones from degenerating from disuse during stays in near weightlessness.
Creatine kinase: An enzyme present in skeletal and cardiac muscle and the brain. Very high levels in the blood can indicate presence of disease or other abnormality.
Creatinine: Creatinine is a substance excreted in the urine and derived from creatine and creatine phosphate in muscle, which serve to maintain adequate amounts of ATP (the source of muscle contraction).
Cross-coupling: A reflex that occurs when a visual scene a subject is looking at is not aligned with the direction of gravity, for example, when the head is tilted. Cross-coupling causes a change in the axis of the eye movement to align with the gravitational reference and not with the visual scene. ***
Crystallographic: Related to the study of crystal form and structure.
Cytochemistry: The study of chemical compounds and their activities in living cells.
Cytogenetic: Science that links the study of inheritance (genetics) with that of cells (cytology); concerned mainly with the study of the chromosomes, their origin, structure, and functions.

D

Demineralization: Demineralization is the loss of minerals, such as calcium from the bones or other mineralized structures of the body.
Densitometry: The measurement of the density or compactness of bone. Also an indirect method of determining body composition; using this method, percentage of body fat is computed from bone density (the ratio of body weight to body volume).
Diffusion: Diffusion refers to the spreading out or dispersing of a material.
Diffusion coefficient: The diffusion coefficient is a numerical measure of the diffusion property that is constant for a specified system. Diffusion refers to the spreading out or dispersing of a material.
DNA: The part of the cell nucleus that is the repository of hereditary characteristics. Dorsal; Dorsal means relating to or situated at or close to the back of the body or to the posterior part of an organ. Dorsiflexion; Dorsiflexion is the backward flexion of the foot or hand or their digits, (bending toward the upper surface). Dorsiflexor; The dorsiflexor is a muscle which turns the foot, hands or fingers upward towards the upper surface.
Dosimeter: A dosimeter is a device used to record the amount of radiation received by workers with X-rays or other radiation, usually consisting of a small piece of photographic film in a holder attached to the clothing. At regular intervals the film is examined to discover the amount of radiation it (and therefore the wearer) has received.
Dosimetry: The accurate determination of dosage, i.e. the quantity of radiation received over a given period of time.
Doubly labeled water: Doubly labeled water is a method of measuring metabolism by using two stable, non-radioactive isotopes deuterium (2H) and oxygen (18O). This method has the advantage that the two metabolic processes in the body involving hydrogen and oxygen, can be monitored in parallel. Deuterium leaves the human body in urine, while the labeled oxygen is found in urine and exhaled CO2. The difference between the two isotopes found in the urine sample is equal to the rate of CO2 production, which indicates the energy consumption.

E

Eccentric: Eccentric refers to a muscle movement causing a lengthening of the muscle; movement of a muscle away from the body.
Echocardiogram: Echocardiogram is an instrument that uses ultrasound (sound waves at extremely high frequencies) to investigate the heart and major blood vessels.
Ecology: The branch of biology concerned with studying the interrelationships of living organisms, specifically their relationships to each other and to the environment.
EEG: A device which records the electrical activity from different parts of the brain and converts it into a tracing called an electroencephalogram or EEG. The machine that records this activity is known as an encephalograph. The pattern of the EEG reflects the state of the patient's brain and the level of consciousness in a characteristic manner.
Egocentric: egocentric motor strategies are those in which the subject concentrates on a body frame of reference rather than on the external world. ***
Electrocardiogram: Electrocardiogram (ECG or EKG) is the graphic record of the heart's action currents obtained with the electrocardiograph, an instrument designed for recording the electrical currents that traverse the heart and initiate its contraction.
Electromyogram: An electromyogram (EMG) is an instrument that records electrical currents generated in an active muscle.
Electrolyte: An electrolyte is a solution, such as sodium chloride, that produces ions (an ion is an atom or group of atoms that conduct electricity). Electrolytes are necessary at appropriate levels for normal bodily functioning. When electrolyte levels become diminished they can be corrected by administering the appropriate substance by mouth or by intravenous drip.
Electromyographic: Electromyographic refers to an electromyogram (EMG), which is an instrument that records electrical currents generated in an active muscle.
Electromyography: Electromyography is the recording of electrical currents generated in an active muscle using an instrument called an electromyogram (EMG).
Embryo: An animal at the early stage of development before birth.
EMG: An electromyogram (EMG) is an instrument that records electrical currents generated in an active muscle.
Endocrine: Pertains to a gland that secretes its products directly into the blood stream.
Enzyme: An enzyme is a protein that, in small amounts, speeds up the rate of a biological reaction without itself being used up in the reaction (i.e., it acts as a catalyst). For example, enzymes present in the digestive juices of the stomach breakdown food into simpler compounds to be absorbed into the body.
Enzyme Linked Immunosorbent Assay: Used for diagnosis of specific infectious diseases. An enzyme is used as the indicator system; when the enzyme and the antigen-antibody complex bind, a color indicator or other easily recognizable sign occurs.
Ergometer: An ergometer is rotary pedal device that provides a calibrated, or specific, resistance. The force required to overcome the resistance is measured as work.
Erythrocyte: An erythrocyte is a red blood cell, a blood cell containing the pigment hemoglobin, the principal function of which is the transport of oxygen.
Erythropoiesis: Erythropoiesis is the process of red blood cell production, which normally occurs in the blood-forming tissue of the bone marrow.
Erythropoietin: Erythropoietin is a hormone secreted by certain cells in the kidney in response to a reduction in the amount of oxygen reaching the tissues; it stimulates red blood cell production.
Exercise capacity: Exercise capacity is the maximum ability of the body to take up and use oxygen to do work. This is often reported as the maximum number of liters of oxygen that the body can use in a minute.
Extensor: An extensor is a type of muscle which works to straighten a limb, the antagonist of a flexor.
ExtraVehicular Activity (EVA): An activity that occurs external to the space vehicle requiring a crew member to wear a life support suit and exit the vehicle.
Extracellular fluid: Fluid situated outside a cell or the cells of the body.

F

Fast twitch: Fast-twitch fiber is a muscle fiber which produces force for rapid movement and exercise.
Fatigability: Fatigability is a measure of the rate at which fatigue is induced.
Fatigue: Fatigue means mental or physical tiredness, usually caused by prolonged or intense activity, but also possibly caused by disease, lack of adequate nutrition or other anomalous factors.
Fatigue test: A fatigue test is a test which determines how much work/activity can be accomplished by different muscles before their efficiency is reduced.
Femur: The femur, also called the thigh bone, is the long bone between the hip and the knee.
Fixative: A chemical which renders a cell or organism suspended or preserved in a stable state, usually so that it can be studied at a later date.
Flexor: A flexor is a type of muscle which works to flex a limb (or bend towards the body); the antagonist of an extensor.
Flow cytometry: A method used to count cells (especially blood cells), using a glass chamber of known volume.
Formaldehyde: A pungent gas; in liquid form, it is used as an antiseptic, disinfectant and fixative for tissues.

G

Gastrocnemius: The gastrocnemius is a muscle that forms the greater part of the calf of the leg; it flexes the knee and foot so that the toes point downward.
Gastrointestinal: Gastrointestinal refers to the stomach and intestines.
Gene: a functional unit of heredity which occupies a specific place on a chromosome. ***
Gene expression: Molecular analysis that helps determine how the specific sequence or part of the DNA sequence is translated.
Genetic program: Also called the genetic code, and referring to the information carried by the genes (DNA and RNA) that determines the sequence of amino acids in every protein and thereby controls the nature of how cells develop, and ultimately how an organism develops, including its appearance, function and instincts.
Gravitoinertial environment: A gravitoinertial environment is an environment in which gravity and inertia exist.
Growth hormone: Growth hormone (somatotropin) is an anterior pituitary hormone that causes growth of almost all cells and tissues of the body.

H

Hamstring: The hamstring is any of the tendons at the back of the knee; they attach the hamstring muscles (the biceps femoris, semitendinosus, and semimembranosus) to their insertions on the tibia and fibula.
Hand Grip Dynamometer: The Hand Grip Dynamometer (HGD) is a device that measures the performance of the wrist flexor muscles. The subject has to actively push against a plate, thereby bending the wrist. At the same time, sensors inside the HGD measure the force.
Hemodynamic: A study of the forces involved in circulating blood through the body.
Hepatic: Relating to the liver.
Herpesvirus: One of a group of DNA containing viruses causing latent infections in man and animals.
Histochemical: The study of intracellular distribution of chemicals, reaction sites, enzymes, etc., often by means of staining reactions, radioactive isotope uptake, or other methods.
Histological: Relating to the science concerned with the minute structure of cells, tissues and organs, and how these structural details relate to their function.
Histological examination: A histological examination is a method of studying the structure of tissues by means of means of special staining techniques combined with light and electron microscopy.
Homeostasis: Homeostasis is the physiological process by which the internal systems of the body (e.g. blood pressure, body temperature, acid-base balance) are maintained at equilibrium despite variations in the external conditions.
Hormone: A hormone is a substance that is produced in one part of the body, passes into the bloodstream and is carried to other distant organs or tissues where it acts to modify their structure of function.
Humoral immunity: Immediate hypersensitivity to an antigen, which triggers antibody production. This is opposed to cell-mediated immunity, which involves white blood cells and is a delayed response to an antigen.
Hydrocarbon: A compound containing only hydrogen and carbon.
Hydrostatic: Relating to the pressure of fluids or to their properties when in equilibrium.
HZE: HZE particles are highly charged and energetic components of cosmic rays. These particles can deposit energy in tissue at a linear rate exceeding 1 GeV cm2 g-1 which is capable of killing a cell if the particle passes near the cell's nucleus.

I

Immune System: The immune system provides the body with a defense against infection, afforded by the presence of circulating antibodies and white blood cells. Antibodies are manufactured specifically to deal with the antigens associated with different diseases as they are encountered, while white blood cells attack and destroy foreign particles in the blood and tissues.
Immunoreactive: Immunoreactive is used to describe a situation where an antigen and antibody are reactive in vitro, i.e. occurring outside the body, traditionally in a test tube.
In vivo: In vivo is a Latin term describing biological phenomena that occur, or are observed occurring, within the bodies of living organisms.
Incubator: A device which maintains controlled environmental conditions, especially used for providing warmth and dryness. Some incubators are specifically designed for cultivating cell cultures and bacteria in Petri dishes. Others are designed for hatching eggs or for protecting animal or human infants.
Inner ear: The inner ear (or labyrinth) is a convoluted system of cavities and ducts comprising the organs of hearing and balance.
Insulin: Insulin is a peptid hormone secreted by the pancreatic islets of Langerhans. It promotes glucose utilization, protein synthesis, and the formation and storage of neutral lipids. Its chemical structure is completely known and insulin obtained from various animals are used in the treatment of diabetes.
Integrated Metabolic Session: To minimize the amounts of blood, urine, and saliva taken from crew members, investigators share samples, (e.g. one sample is drawn, processed and distributed to multiple investigators, who then perform their own unique analysis).
Intervertebral: Intervertebral refers to the flexible plate of fibrocartilage that connects any two adjacent vertebrae in the backbone or spine.
Ionized calcium(Ca): Ionized calcium(Ca) is the ionic (i.e., charged) form of calcium that plays a role in muscle contractions and in regulating levels of Parathyroid Hormone.
Ionizing radiation: Radiation, such as that found in cosmic rays, which causes atoms in the material through which it passes, to lose electrons. The electrons are pulled away from the atoms by the strong attractive force between the positively charged proton (or heavy ion) and the orbital electron. Ionizing radiation can kill cells outright, damage their genetic material, and, in some instances, induce cancer.
Isokinetic: Isokinetic relates to movement of the body.
Isometric: Isometric describes the contraction of muscles when the fibers are called upon to contract and do work, but despite an increase in tension, do not shorten in length. Isometric exercises can be induced in muscles that are used when a limb is made to pull or push against something that does not move.
Isothermal: Isothermal means with or at equal temperatures, or at a constant temperature.
Isotope: An isotope is one of a series of chemical elements that have nearly identical chemical properties but differ in their atomic weights and electric charge and in may case are radioactive. Their unique properties allow them to be used as tracers.
Isovelocity: Isovelocity is the rate of movement, specifically, the work accomplished per unit time.

J-K

L

Lateralis: The term lateralis indicates that a structure is located away from the mid-line of the body.
Left ventricular stroke volume: Left Ventricular Stroke Volume is the volume of blood (normally about 70 ml) ejected from the heart into the aorta during the contraction of the ventricles, systole. Same as stroke volume.
Lymphocytes: Lymphocytes are a variety of white blood cells present in blood, lymph nodes, spleen, thymus gland, gut wall and bone marrow; they produce circulating antibodies and T-lymphocytes, which are primarily responsible for cell-mediated immunity and can differentiate into helper, killer or suppressor cells.

M

Macrophages: Macrophages are large scavenger cells present in connective tissue and many major organs and tissues including the bone marrow, spleen, lymph nodes, liver and the central nervous system.
Magnesium: Magnesium is a metallic element essential to life; necessary for the proper functioning of muscle and nervous tissue.
Magnetic Resonance Imaging: Magnetic Resonance Imaging (MRI) is a noninvasive method which utilizes the properties of magnetism to create nondestructive, three-dimensional, internal images of the soft tissues of the body, including the brain, spinal cord and muscle.
Manometer: An instrument used to measure the pressure of any fluid or the difference in pressure between two fluids, whether gas or liquid.
Melatonin: Melatonin is a substance secreted by the pineal gland that passes by way of the blood or through the fluid of the third ventricle to the anterior pituitary gland to control gonadotropic hormone secretion; melatonin can be manufactured artificially and is showing several possible beneficial medical uses.
Metabolic: Metabolic relates to metabolism, the step-wise breakdown or creation of complex organic constituents in the body. The process results in the liberation of energy used by the body and its processes.
Metabolism: Metabolism is the sum of all the chemical and physical changes that take place within the body and enable its continued growth and functioning. Metabolism involves the breakdown of complex organic constituents of the body with the liberation of energy, which is required for other processes, and the building up of complex substances, which form the material of the tissues and organs.
Metabolite: Metabolites are substances that take part in the process of metabolism, which involves the breakdown of complex organic constituents of the body with the liberation of energy for use in bodily functioning.
Methane: An odorless gas produced by the decomposition of organic matter.
MGBX: The Microgravity Glove Box, or MGBX, provides a clean and sealed work cabinet for the preparation and performance of experiments within the laboratory environment of the Priroda module of the Russian Space Station Mir. Experiments are inserted into the unit and manipulated by gloved crewmembers. The MGBX prevents experiment materials from entering the module atmosphere and provides basic services to the experiments, such as electrical power, lighting, data recording, cooling, some small stowage, air circulation, air filtering, gas sensing, and a means for manual observation and video recording by the crew. The MGBX also monitors temperature, pressure, and humidity. Experiments involving combustion, hazardous operations, or experiments that need to be isolated from the normal Mir environment can be accommodated with the MGBX.
Microacceleration: Microacceleration is a minute (very small) acceleration force. Acceleration is measured as the rate of change of velocity with respect to time.
Microbes: A microorganism; any organism too small to be visible to the naked eye, e.g. bacteria, viruses, protozoa and some fungi.
Microbial: Of or relating to microbes (microscopic organisms such as bacteria or viruses).
Microbiology: Microbiology is the study of microorganisms. Microbiology in relation to medicine is concerned mainly with the isolation and identification of the microorganisms that cause disease.
Microbiota: Microbiota are microscopic organisms in a specific environment.
Microflora: Microflora are very small plants.
Microgravity: A state where the gravity is reduced to almost negligible levels.
Microgravity Sciences: A research program which studies fundamental science, combustion science, materials science and biotechnology in the space environment in order to better understand gravity dependent physical phenomena.
Microorganisms: A microorganism is any organism too small to be seen by the naked eye, e.g. bacteria, viruses, protozoa and some fungi.
Microvasculature: Microvasculature refers to very small blood vessels.
Mineralogical: Mineralogy is the scientific study of minerals, which are any naturally occurring, homogeneous inorganic substances having a definite chemical composition and characteristic crystalline structure, color and hardness.
Mitochondria: Mitochondria is a subcellular organelle found in eukaryotes which is between 0.2-0.5 micrometers in length. It consists of a double membrane surrounding a matrix, with the inner membrane folded into projections called cristae. The walls of these cristae are the site of energy production for the cell, because of this the mitochondria have been called the powerhouse of the cell. The mitochondria are found in large numbers in cells with high energy needs. The mitochondria are self replicating and contain DNA by which they control synthesis of their own proteins.
Mitogen: A mitogen is any substance that causes cells to begin division (mitosis).
Monocytes: A monocyte is a variety of white blood cell with a kidney-shaped nucleus; its function is the ingestion of foreign particles such as bacteria and tissue debris.
Mononuclear: Having one nucleus, particularly a blood cell, such as a monocyte or lymphocyte.
Morphological: Morphological means relating to structure or anatomy.
Motility: Motility is the power to move spontaneously.
Motor units: Motor units are different muscle parts constituting the muscle; each unit can be stimulated independently.
MRI: Magnetic Resonance Imaging (MRI) is a large noninvasive device which utilizes the properties of magnetism to create nondestructive, three-dimensional, internal images of the soft tissues of the body, including the brain, spinal cord and muscle.
Musculoskeletal: Musculoskeletal refers to the system of muscles and bones.
Myofibril: Myofibril is one of numerous contractile filaments found within the cytoplasm of striated muscle cells. When viewed under a microscope, myofibrils show alternating bands of high and low refractive index, which give striated muscle its characteristic appearance.
Myoglobin: Myoglobin is a respiratory pigment in muscle tissue that serves as an oxygen carrier.
Myosin: Myosin is the most abundant protein in muscle fibrils, comprising up to 50% of the total muscle proteins. Myosin gives the muscle its important properties of elasticity and contractility. With actin, it comprises the principal contractile element of muscles.

N

Natural Killer Cells: Natural Killer Cells are a specific type of lymphocyte (white blood cell) which kill '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.
Negative energy balance: A negative energy balance occurs when the body expends more energy (measured as calories) than it receives through the consumption of food.
Nematode: Parasitic roundworms which are unsegmented, typically cylindrical and long, tapered at both ends, fundamentally bilaterally symmetrical, and without any appendages. They have digestive, nervous and reproductive systems.
Neuromuscular: Neuromuscular means of or relating to nerves and the muscles they supply.
Neuromuscular junction: A neuromuscular junction is where the nerve meets the muscle, specifically the meeting point of a nerve fiber and the muscle fiber that it supplies. Between the enlarged end of the nerve fiber and the membrane of the muscle is a gap across which a neurotransmitter, usually a chemical substance, must diffuse from the nerve to trigger contraction of the muscle.
Neuron: A neuron is a nerve cell, one of the basic functional units of the nervous system; it is specialized to transmit electrical nerve impulses and so carry information from one part of the body to another.
Neuropharmacological: Relating to drugs that exert effects on nerve tissue.
Neurosensory: Relating to the sensory aspects of the nerves and nervous system, i.e. the ability of the nerves to sense stimuli from the body itself or from the external environment.
Neurovestibular: Neurovestibular relates to the interaction between the brain and the vestibule, especially the vestibule of the ear, a cavity situated at the entrance to bony labyrinth that contains the saccule and utricle -- the organs of equilibrium.
Nitrogen: An element that is a component of all proteins; it is essential to the process of building tissue in plants and animals .
Nystagmus: Rhythmic, constant, involuntary movements or oscillations of the eyeballs, whether pendulum-like or jerky.

O

Oculomotor: Concerned with eye movement.
1-G: Gravity found on Earth.
Ontogenesis: Ontogenesis refers to the entire development of an organism from fertilization to completion of life history.
Optokinetic: Optokinetic refers to the occurrence of intermittent rotation of the eye when the subject looks at moving objects. In other words, when the visual scene continually moves before the eyes, such as when a person is riding in a car or turning around, the eyes fix on one highlight after another in the visual field, jumping from one to the next at a rate of two to three jumps per second. The jumps are called saccades and the movements are called optokinetic movements.
Organic: Organic means of or originating from carbon compounds.
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 reaching the brain. Astronauts often experience temporary orthostatic intolerance when remaining upright after returning from stays in space, since their blood volume is reduced in weightlessness and the pull of gravity does not allow blood to reach their heads.
Oscillation: Oscillations, as they apply to microgravity experiments, are vibrations. However, oscillations can refer to any steady back and forth movements.
Osmoreceptor: Any of the group of structures found in the hypothalamus that respond to changes in the osmotic pressure of the blood.
Osteoblast: A type of cell that is responsible for the formation of bone.
Osteoporosis: Osteoporosis is the loss of bony tissue, resulting in bones that are 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 localized osteoporosis of adjacent bone.
Otolith: An otolith (or otoconium) is one of the small particles of calcium carbonate in the saccule or utricle of the inner ear. Pressure of the otoliths on the hair cells of the macula provide sensory inputs about acceleration and gravity.
Oxalate: Oxalate is a salt of oxalic acid.
Oxidative: Oxidative relates to oxidation. Oxidation is the combination of a substance with oxygen. Oxidation can also describe a type of reaction in which the atoms in an element lose electrons and the valence is correspondingly increased.

P

Parathyroid Hormone: Parathyroid hormone (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 interaction to operate, except possibly for the need to be activated, placed in a certain position or shut down.
Pathogenic: Causing disease or abnormality.
Peripheral mononuclear cells: Refers to monocytes and lymphocytes which circulate in the bloodstream.
Peripheral Venous Pressure: Peripheral venous pressure is the pressure in the peripheral veins, which is usually about 4 to 7 mm Hg; this pressure is due to the considerable resistance to blood flow in the large veins.
Peroxidation: Peroxidation is the act of an enzyme, called peroxidase, catalyzing the transfer of oxygen from hydrogen peroxide or an organic peroxide to a suitable substrate and thus bringing about oxidation of the substrate. It causes breakdown of peroxide only in the presence of a suitable oxidizable substrate.
Perturbations: Perturbations are disturbances or abnormalities.
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.
Pharmacokinetic: Pharmacokinetic is 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. Pharmacology; Pharmacology is the science of the properties of drugs and their affects on the body.
Phosphate: Phosphate, a salt or ester of phosphoric acid, is an important chemical compound for the maintenance of the blood acid-base balance and bone mineralization.
Photosynthesis: The process by which green plants use the energy of light and a special substance called chlorophyl to synthesize carbohydrates (energy) from carbon dioxide and water.
Physiological: Of or relating to physiology, the science that studies the function of the body.
Pitch: Pitch refers to the up or down angle of the nose off of the horizonal plane.
Plantarflexion: Plantarflexion is the bending of the toes (or fingers) downward, toward the sole (or palm).
Plantaris: The plantaris is a the muscle in the leg that is used to flex the foot.
Plasma: Plasma is the fluid in which the blood cells are suspended; it consists of a solution of various inorganic salts, such as sodium, potassium and calcium, and protein, as well as other trace substances.
Polymerase Chain Reaction: Polymerase Chain Reaction, or PCR, is a process which permits scientists to make unlimited copies of genes. This is done beginning 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.
Postural equilibrium: Postural equilibrium is a reflexive mechanism which anticipates changes in body orientation when the body becomes off balance and makes appropriate adjustments of the body to prevent falling; such as, when the body is suddenly pushed to the right, even before it can fall, the right leg extends instantaneously in a reflexive motion.
Potable: Potable means water that is fit to drink.
Potassium: The principal cation in intracellular fluid and is of primary importance in its maintenance. Proper balance of potassium, calcium and magnesium ions are essential for normal excitability of muscle tissue.
Proteins: Proteins are one of a group of organic compounds of carbon, hydrogen, oxygen and nitrogen with sulfur and phosphorus possibly present. The protein molecule is a complex structure made up of one or more chains of amino acids, which are linked by peptide bonds. Proteins are essential constituents of the body; they form the structural material of muscles, tissues, organs, etc. and are equally important as regulators of function as enzymes and hormones; they can also be converted into glucose and used as an energy source by the body.
Proton: A positively-charged particle forming the nucleus of hydrogen and present in the nuclei of all elements.
Provocative: A provocative move is one which will induce, or cause, certain symptoms or effects.
Psoas: The psoas is one of two muscles that run from the spine to the top of the upper leg bone and act to flex the lower back and thigh.
Psychosomatic: Psychosomatic means pertaining to the relationship of the mind and body.
Pulmonary: Pulmonary relates to the lungs.

Q

Quadriceps: The quadriceps is one of the great extensor muscles of the legs situated in the thigh.
Quadriceps femoris: The quadriceps femoris is a muscle of the thigh.
Quail: A small, short-tailed chickenlike bird.

R

Radiation dose: The quantity of radiation received at one time, or in fractional amounts within a given period of time.
Radiometer: A radiometer is a device for determining the penetrative power of x-rays; also called a roentgenometer.
Readaptation: Adjustment of the organism and its physiological processes to its previous state. For example, after remaining in bed or a wheelchair for a several weeks, patients must readapt to earth gravity by strengthing their muscles.
Recovery: The day and time when the spacecraft lands and human, animal and plant organisms are re-introduced to earth gravity; sometimes abbreviated R+0, to indicate zero days after recover, i.e., day of landing.
Red blood cell mass: Red blood cell mass is the amount of red blood cells in the body.
Remote sensing: Remote sensing is the ability to measure, observe or study something distant through the use of special instruments, devices or electronics.
Renal: Relating to the kidney.
Renin: Converts angiotensinogen to angiotensin, a substance which constricts blood vessels.
Reserve Science Activity: A science activity that is not scheduled in the crew timeline. These activities are performed when additional crew time becomes available, e.g. an experiment is concluded ahead of schedule.
Resorption: Resorption is the act of removal by physiological absorption.
Roll: Roll is the up or down angle of the wing off of the horizonal plane.
R+0: This term refers to landing day of the Shuttle. Literally, it means Recovery plus 0 days. ***

S

Saccade: Refers to a rapid, jerky or quick eye movement. ***
Saccule: The saccule is the smaller of the two membranous sacs within the vestibule of the ear; it forms part of the membranous labyrinth. ***
Semicircular Canals: The three bony tubes in the labyrinth of the ear within which the membranous semicircular ducts are located; they lie in planes at right angles to each other and are known as the anterior, posterior and lateral semicircular canals. ***
Sensory-motor: Sensory-motor means both sensory and motor, i.e., a nerve with both functions.
Skeletal muscle: Muscles that connect bones together.
Slow twitch: Slow-twitch muscle fibers generate force for prolonged, continuous activity; they are most active in resisting gravity and are important in maintaining posture.
Sodium: Sodium is a silver-white, soft, waxy ductile element of the alkali metal group.
Sodium urate: Crystals found in the urine, blood, and tophi or calareous deposits in tissues.
Soleus: The soleus is the broad, flat muscle in the calf of the leg, beneath the gastrocnemius muscle, that flexes the foot so that the toes point downwards.
Somatic: Refers to the non-productive parts of a body.
Spacehab: Spacehab is a pressurized module designed to be attached to the Orbiter middeck Smaller in size than the Spacelab, it provides approximately 1100 cubic feet of additional volume for support of crew and experiments. It is connected to the Space Shuttle by a modified tunnel adapter, and draws resources such as cooling, power, data and housekeeping systems from the Shuttle's cabin and cargo bay/payload support provisions. The Spacehab module can accommodate various quantities and sizes of equipment, hardware lockers, and racks.
Spacelab: Spacelab is a reusable system of space flight hardware that includes a pressurized laboratory and unpressurized pallets - both are carried in the Space Shuttle's payload bay. Most life sciences experiments are placed in the pressurized laboratory. Equipment is mounted along the walls and floor of the pressurized cylindrical Spacelab module. Crewmembers float into the Spacelab through a tunnel adapter that transits from the airlock in the middeck to the Spacelab.
Space motion sickness (SMS): Space motion sickness, or space adaptation syndrome, is a syndrome experienced by space travelers that is similar to motion sickness on earth (air sickness, car sickness, sea sickness), causing nausea, vertigo and sometimes vomiting. It effects about 60% of the people who travel in space with varying degrees of severity. Also called space adaptation syndrome.
Spectrometer: A spectrometer is any instrument used for measuring the intensity and wavelengths of visible or invisible electromagnetic radiation.
Stroke Volume: Stroke volume is the volume of blood - normally about 70 ml - ejected from the heart into the aorta during the contraction of the ventricles (systole)
Struvite: Struvite takes the form of crystals of magnesium ammonium phosphate which are present in some renal stones.
Sulfate: A salt of sulfuric acid.
Svet: Russian word meaning light.

T

T4: T4 is the symbol for thyroxin, the hormone produced by the thyroid.
T-cells: T-cells or T-lymphocytes are responsible for cell-mediated immunity. They are formed in the thymus gland and react highly specifically against the particular type of antigen that initiated their development.
Testosterone: Testosterone is a principal male sex hormone. Though this hormone normally (and necessarily) occurs in small amounts in females, it is chiefly known as the hormone responsible for stimulating the development of male sex organs and male secondary sexual characteristics, e.g. facial hair, deepening of the voice, and muscle development.
Thermophilus: Pertaining to thermophile; an organism that grows best at a temperature of 50 degrees C.
Thermoregulation: The process of regulating body temperature.
Titer: Titer is the determination of a measurement of a substance in solution by volumetric means.
Torque: Torque is the turning effect produced when force is applied to a rotational axis.
Torque Velocity Dynamometer: The Torque Velocity Dynamometer (TVD) is a multi-purpose workstation designed to support all musculoskeletal investigations performed on the LMS (Life and Microgravity Sciences) mission, STS-78. The TVD measures torque, which is the turning effect produced when force is applied to a rotational axis. The contracting muxcles associated with elbow and ankle joints apply force against a lever which measures the torque produced.
Total body water: All the water in the body, including water inside and outside the cells.
Toxicological: the study of poisons and the treatment of poisoning.
Tracer: An isotope of a chemical element, for example radioactive forms of carbon 14, which is administered in some way to organisms so that its path or location may be followed within the organism or in the products of metabolism.
Triceps: The triceps is a muscle with three heads of origin, particularly the triceps brachii, which is situated on the back of the upper arm and contracts to extend the forearm.
Tuberculosis: An infectious disease caused by a bacteria, Myobacterium tuberculosis that causes inflammatory infiltrations, formation of tubercles, caseation, necrosis, abscesses, fibrosis, and calcification of the lungs and in some cases the gastrointestinal system, genitourinary tracts, bones, joints, nervous system, lymph nodes and skin.

U

Ultrasound: The use of sound with a frequency higher than 30000 Hz to obtain images for medical diagnostic purposes.
Uric acid: Uric acid is the end product of urine breakdown; it is the major form in which metabolic nitrogen is excreted.
Utricle: The utricle is the larger of the two membranous sacs within the vestibule of the ear; it forms part of the membranous labyrinth.

V

Valsalva Maneuver: The valsalva maneuver is an attempt to forcibly exhale with the glottis, nose and mouth closed.
Vapor-diffusion: A method of growing protein crystals.
Vastus: Vastus means literally "great muscle."
Velocity: Velocity is the rate of movement, specifically, the distance traveled per unit of time.
Ventral: Ventral means relating to or situated at or close to the front of the body or to the anterior part of an organ.
Vestibular: "Vestibular" relates to a vestibule, specifically the vestibule of the ear, a cavity situated at the entrance to the bony labyrinth that contains the saccule and utricle -- the organs of equilibrium.
Virus: Virus is the term for a group of microbes which with a few exceptions are capable of passing through fine filters that retain most bacteria. Viruses are incapable of growth and reproduction outside of a living cell. Most viruses contain either DNA or RNA, but a select group called retroviruses may contain both. Viruses replicate by releasing their DNA or RNA into the host cell; the viral DNA or RNA in turn directs the host cell 's "machinery" to churn out more viral DNA or RNA. Classification of viruses depends on mode of transmission, host range, symptoms and other factors.
Visuo-motor: Both visual and motor, i.e. a nerve with both functions.
Void: To empty or evacuate body waste. ***
Volitional: Volitional means voluntary, or done by an act of will.
Volume of inspired oxygen: The volume of inspired oxygen is the maximum oxygen uptake by the lungs; usually referred to as VO2 Max.
Voluntary: Voluntary means relating or acting in obedience to the will; not obligatory.
VO2 Max: The VO2 Max, or volume of inspired oxygen, is the maximum oxygen uptake by the lungs.

W-X

Y

Yaw: Yaw is the left or right angle of the vehicle nose, relative to the direction of motion, in the horizonal plane.

Glossary

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