Macrophages-METS

macrophages cell type derived from blood monocytes or through local proliferation and that reside in many locations in the lung including the pleura, interstitium, and epithelial surface; associated with defending the lung against inhaled agents, and phagocytosing particulates and debris.

macula a small spot or a colored area

magnesium sulfate an electrolyte solution used to treat polymorphic ventricular tachycardia (with pulse), torsade de pointes (with pulse), and ventricular fibrillation/pulseless ventricular tachycardia if indicated.

magnetic PEEP valve a valve that maintains a positive end­expiratory pressure by means of a magnetically activated component.

magnetic resonance imaging (MRI) useful imaging that takes advantage of nuclear magnetic resonance, in which nuclei with odd numbers of protons and a magnetic moment become aligned when they are placed in a strong magnetic field and are subsequently excited to a more energetic state with the addition of a radio frequency pulse; once allowed to relax, excited protons emit a resonance signal that is a reflection of the number of protons and their nuclear environment, and different relaxation signals are generated depending on the pulse sequence, the way in which the protons within the nuclei are excited.

magnitude pertaining to size.

Mahaim fibers see Nodoventricular/fasciculoventricular fibers (Mahaim fibers).

main solenoid the master control device in a gas delivery system.

mainstream nebulizer a nebulizer that introduces the jet stream into the main gas flow.

malaise a feeling of discomfort, illness, or uneasiness  

malar pertaining to the cheek or cheekbones.

malformation deformity; abnormal shape or structure, especially congenital.

malignant tending to become worse and to cause death; in the case of a cancer, it is anaplastic, invasive, and metastatic.

malpractice (in law) professional negligence that is the proximate cause of injury or harm to a patient, resulting from a lack of professional knowledge, experience, or skill that can be expected in others in the profession or from a failure to exercise reasonable care or judgment in the application of professional knowledge, experience, or skill

managed care health care system that seeks to eliminate redundant services and facilities, thereby reducing costs, through administrative control over primary health care services.

managed care organizations integrated network of doctors, hospitals and other health care providers that deliver health services to an insured population. The four different types of managed care organizations are the health maintenance organization (HMO), the preferred provider organization (PPO), the exclusive provider organization (EPO), and point-of-service plan (POS).

mandatory breath inspiration that is machine-triggered and/or machine-cycled. 

mandatory minute volume (MMV) a mode of ventilation in which the minimum minute volume is predetermined and delivered.

mandatory patient-triggered breaths (MPTB) the number of patient-triggered breaths a patient must initiate per minute during SIMV.

manifold a system of interconnected devices such as a gas manifold. Two or more cylinders connected to regulators and a metering device or a breathing manifold. The exhalation valve, tubing, and nebulizer making up a ventilator circuit.

manometer ports orifices from which pressure readings are obtained by connecting pressure manometers.

manometric pressure static fluid pressure generated by the weight of the fluid and which varies on the basis of the density of fluid and height, reflecting the force of gravity.

Mantoux test placement of purified protein derivative (PPD) subcutaneously to detect the presence of an immune response to mycobacteria by eliciting a delayed-type hypersensitivity response.

manual resuscitator usually a ventilatory bag-valve device consisting of a self-inflating bag, an air-intake valve, a nonrebreathing valve, an oxygen inlet nipple, and oxygen reservoir to aid in resuscitation and breathing.

MAO abbreviation for monoamine oxidase, an enzyme that catalyzes the oxidation of amines

MAO inhibitor any of a chemically heterogeneous group of drugs used primarily in the treatment of depression or anxiety, and sometimes hypertension; MAO inhibitors may interact with a variety of foods and indirect acting adrenergics such as ephedrine, causing severe hypertensive episodes

manubrium the upper triangular portion of the sternum

marasmus protein-energy malnutrition due to starvation

marked bradycardia a bradycardia with a heart rate between 30 and 45 beats per minute or less accompanied by hypotension and signs and symptoms of decreased perfusion of the brain and other organs.

mask CPAP continuous positive airway pressure (CPAP) administered by face mask, relying on the patient to perform ventilation.

masking research technique for ensuring that the investigators and the participants are as aware as possible of the treatment being studied to avoid any tendency to prefer a specific outcome (bias).

mass medial aerodynamic diameter (MMAD) measurement that expresses the geometric size of the particles of an aerosol; for medical use, aerosol generators produce respirable particles with a mass median aerodynamic diameter (MMAD) between 1 to 5 µm.

mass number sum of the protons and neutrons inside the nucleus of an atom; often used interchangeably with the term "atomic weight."

mass spectrometer instrument capable of measuring all respiratory gases, including respiratory and anesthetic gases, breath by breath with greatest accuracy and with multichanneled units available to monitor several patients simultaneously; system aspirates sample gas into a vacuum chamber where it is ionized by an electron beam, accelerating the charged molecules through a magnetic field, where dispersion according to their mass and charge separates them before they reach a panel of detectors.

mass spectrometry an analytic method for assessing the concentration of gas mixtures based on their separation by molecular weight

mast cells cells that produce histamine and leukotrienes which constrict airway smooth muscles; two types, classified according to neutral protease composition (chymase and/or tryptase).

mastectomy surgical removal of breast tissue; can be partial or radical

mastoid process projection of the posterior portion of the temporal bone; gives attachment to the sternocleidomastoid, splenius capitis, and longissimus capitis muscles.

MAT see Multifocal atrial tachycardia (MAT).

maxillary of or pertaining to the maxilla, or upper jaw maxillofacial of or pertaining to the upper jaw, nose, and cheek

maximum expiratory pressure (MEP) a measure of the output of the expiratory muscles against a maximum stimulus, measured in cm H20 positive pressure

maximum inspiratory pressure (MIP) a measure of the output of the inspiratory muscles against a maximum stimulus, measured in cm H20 negative pressure. Also known as negative inspiratory force (NIF) or maximum inspiratory force (MIF)

maximum inspiratory time control the mechanism that determines the allowable length of inspiration.

maximum pressure control sets the highest allowable ventilator pressure.

maximum voluntary ventilation (MVV) the maximum volume of air in liters per minute that a subject can breathe during a 12 to 15 second period. It is a very patient-dependent test. Formerly called the maximum breathing capacity (MBC)

McBurney's point the point of special tenderness in acute appendicitis; corresponds with the normal position of the base of the appendix

MCL1 see Monitoring ECG lead MCL1.

MD Consult internet site designed to deliver authoritative medical information to physicians, available by subscription to its accesses; searches via MEDLINE, textbooks, practice guidelines, patient education handouts, and drug information.

MDI abbreviation for metered dose inhaler; a pressurized cartridge used for self-administration of exact dosages of aerosolized drugs

MDR-TB acronym for multiple drug resistant tuberculosis

mean occupying a middle position; being near the average.

mean airway pressure (MAP) the average of the pressures occurring in the airway during the respiratory cycle.

mean airway pressure average pressure within the airway during one complete respiratory cycle; directly related to the inspiratory time, respiratory rate, peak inspiratory pressure, and positive end-expiratory pressure (PEEP).

mean QRS axis the average of all the ventricular vectors; the QRS axis, or simply, the axis.

mean vector an average of one or more vectors.

mechanical relating to physical properties.

mechanical insufflation-exsufflation technique in which a device inflates the lungs with positive pressure followed by a negative pressure to simulate a cough. Treatment consists of five cycles of MIE followed by 20 to 30 seconds of normal breathing, with repetitions until secretions are cleared.

mechanoreceptor receptor that receives mechanical stimuli such as pressure from sound or touch.

meconium thick, dark green material that collects in the intestines of the full-term fetus and forms the first stools of a newborn; a mixture of intestinal gland secretions, some amniotic fluid, and intrauterine debris, such as bile pigments, fatty acids, epithelial cells, mucus, lanugo, and blood.

meconium aspiration syndrome condition that develops when the fetus or newborn inhales meconium; the most common cause of severe hypoxemic respiratory failure; can block the air passages and cause failure of the lungs to expand or other pulmonary dysfunction such as pneumonia or emphysema.

meconium ileus obstruction of the small intestine in the newborn resulting from an impaction of thick, dry, cohesive meconium, usually occurring at or near the ileocecal valve.

medial pertaining to the middle.

mediastinal shift abnormal movement of the structures within the mediastinum to one side of the chest cavity

mediastinoscopy examination of the mediastinum, using an endoscope with light and lenses inserted through an incision in the suprasternum.

mediastinum a part of the thoracic cavity in the middle of the thorax, between the pleural sacs containing the two lungs. It extends from the sternum to the vertebral column and contains all the thoracic viscera except the lungs. It is enclosed in a thick extension of the thoracic subserous fascia and is divided into the cranial part and the caudal part.

mediated between two parts or sides.

Medicaid payment program funded jointly by federal and state governments to pay for medical services for the elderly, disabled, poor, and dependent children.

medical gas cylinders containers used to store medical gas. They range from small, lightweight units containing a few cubic feet of gas to large cylinders of several hundred cubic feet. DOT regulations specify that high-pressure medical gas cylinders be made of seamless construction from high-quality steel, chromium-molybdenum alloy, or aluminum.

medical gases gases used for medical purposes.

medical record collection of documentation of patient assessments, problem identification, care plans, treatments, and outcomes, typically including discharge summaries, progress notes, physician orders, laboratory results, and flow sheets, as well as additional media, which may include online reports, photographs, videotapes, films, and audio recordings.

Medicare Federal government's health insurance program for the elderly, the disabled, and persons with certain diseases, such as end-stage renal disease.

medulla the most internal part of an organ or structure; for example, medulla oblongata, the bulbous portion of the spinal cord just above the foramen magnum that contains the cardiac, respiratory, and vasomotor 'centers'

medulla oblongata part of the brainstem connecting the cerebral hemispheres with the spinal cord; it contains specialized nerve centers for special senses, respiration, and circulation, including the sympathetic and parasympathetic nervous systems with their respective cardioaccelerator and cardioinhibitor centers.

megakaryocyte a large bone marrow cell having large or many nuclei

megaloblastic pertaining to abnormally large red blood cells found in pernicious anemia

melanin the black pigment found in the basal layer of the epidermis

melting point the temperature at which solids begin to turn into liquids. The same as freezing point.

membrane concentrator an oxygen concentrator that separates oxygen from air by means of a selectively permeable membrane.

membrane potential the electrical potential measuring the difference between the interior of a cell and the surrounding extracellular fluid.

meningitis inflammation of the coverings around the brain and spinal cord

MEP abbreviation for maximum expiratory pressure; a measure of the output of the expiratory muscles against a maximum stimulus, as measured in cm H20 positive pressure

mEq abbreviation for milliequivalents.

mercury barometer a device for measuring atmospheric pressure by the change in the height of a mercury column.

mesoderm the middle of the three cell layers of the developing embryo, which lies between the ectoderm and endoderm.

mesothelioma a rare malignant tumor of the mesothelium of the pleura or peritoneum, associated with earlier exposure to asbestos

metabolic acidosis a decrease in pH associated with a loss of buffer (HC03-).

metabolic alkalosis an increase in pH associated with an increase in buffer (HC03-).

metabolism sum of all physical and chemical changes that take place within an organism; all energy and material transformations that occur within living cells.

metastasis process by which tumor cells spread to distant parts of the body.

meter a metric unit of linear measurement. One meter is equal to 1000 millimeters, or 39.37 inches.

metered-dose inhaler (MDI) a type of self-propelled nebulizer that is designed to administer individual puffs of a concentrated form of a medication.

methacholine chloride a drug that has the capability of producing a parasympathomimetic response, including the triggering of bronchospasm.

methemoglobin form of hemoglobin that is produced when the iron in heme is oxidized from Fe+2 to Fe+3

methemoglobinemia the presence of methemoglobin values that are greater than normal (greater than 1.5% of total hemoglobin).

methylxanthine traditional agent in the care of patients with COPD; declining in popularity for long-term care. Methylxanthines, however, provide significant bronchodilator effects in patients with COPD, although less than that observed with anticholinergic and β2-agonist agents.

metoprolol a beta blocker. see Beta blockers.

metronome an electronic or mechanical instrument that uses a pulselike sound or light to indicate a regular tempo or rhythm. Metronomes are commonly used in music.

METS abbreviation for the multiple equivalents of resting O2 consumption, an indirect measure of physiological work performed during exercise and stress testing

mg-Monitoring Lead MCL6

mg abbreviation for milligrams.

µ.g. abbreviation for microgram.

microaerosol an extremely fine aerosol of uniform and small particle size produced by sequential baffling and characterized by mass median diameters that are generally less than 1.0 pm

microatelectasis localized or focal atelectasis that may not manifest itself on radiographic examination

microembolization embolization due to extremely small bloodborne particles, usually smaller than that visible with the naked eye

micrognathia underdevelopment of the jaw, especially the mandible

microgram (µ.g) a metric unit of measurement of weight. One thousand micrograms are equal to 1 milligram.

microprocessor small capacity computers designed to monitor and control specific functions.

microswitches small control devices that institute or halt processes.  

microvilli minute cylindrical processes on the free surface of a cell (especially cells of the proximal convoluted renal tubule and those of the intestinal epithelium), which increase the surface area of the cell.  

mid axillary of or pertaining to the imaginary line drawn vertically downward from the middle of the axilla

midclavicular of or pertaining to the imaginary line drawn vertically downward from the middle of the clavicle midline an imaginary line that divides the body into right and left halves

midclavicular line an imaginary line beginning in the middle of the left clavicle and running parallel to the sternum slightly inside the left nipple.

midprecordial (or anterior) leads leads V3 and V4

midscapular of or pertaining to the imaginary line draw vertically downward from the middle of the scapula

midsternal of or pertaining to the imaginary line vertically bisecting the sternum

MIGET Multiple inert gas elimination technique; based on the straightforward principles governing inert gas elimination by the lung, such that when an inert gas in solution is infused into systemic veins, the proportion of gas eliminated by ventilation from a lung unit depends only on the solubility of the gas and the VA/Q ratio of that unit.

mild bradycardia a bradycardia with a heart rate between 50 and 59 beats per minute and absence of hypotension and signs and symptoms of decreased perfusion of the brain or other organs.

mild intermittent asthma least severe of the four classes of asthma severity, characterized by symptoms of coughing or wheezing less than 2 times per week with asymptomatic or normal peak expiratory flows (PEF) between brief exacerbations, nocturnal symptoms of coughing, wheezing, or breathlessness less than 2 times per month, and measured FEV1 or PEF consistently more than 80% of predicted, while maintaining less than 20% variability in PEF routinely.

mild persistent asthma category of asthma characterized by symptoms of coughing or wheezing more than 2 times per week but less than once per day with symptoms that affect normal daily activities of living or normal nighttime sleep patterns, nocturnal symptoms of coughing, wheezing, or breathlessness more than 2 times per month, and measured FEV1 or PEF consistently more than 80% of predicted or personal best, while maintaining approximately 20% to 30% variability in PEF rates.

mild sinus bradycardia see Mild bradycardia.

milliequivalents (mEq) the weight of a substance dissolved in 1 milliliter of solution.

milligram (mg) a metric unit of weight. One thousand milligrams are equal to 1 kilogram, or 2.2 pounds.

milliliter (ml) a metric unit of measurement of volume. One thousand milliliters are equal to 1 liter, or 1.1 quarts.

millimeter (mm) a metric unit of linear measurement. One thousand millimeters are equal to 1 meter, or 39.37 inches.

millimeter of mercury (mm Hg) a metric unit of weight used in the determination of blood pressure.

millimole an SI unit of matter equal to one-thousandth of a mole (a mole is any quantity of matter that contains 6.023 x 1023 atoms, molecules, or ions)

millivolt (mV) a unit of electrical energy. One thousand millivolts are equal to 1 volt.

minimum minute volume a control setting that determines the lower limit of acceptable minute ventilation.

minimal occluding volume (MOV) the least amount of air needed to achieve a seal in a cuffed endotracheal or tracheostomy tube.

minute volume control the mechanism that presets the minute volume delivered by a ventilator.

MIP abbreviation for maximum inspiratory pressure, the negative pressure generated during a maximally forced inspiratory effort against an obstruction to flow; also called negative inspiratory force (NIP) and Plmax

misallocation the process of prescribing diagnostic or treatment services when not indicated, consisting both of "over-ordering" and "under-ordering" services

mitosis the process whereby a cell normally replicates itself, forming two daughter cells, each with the same number of chromosomes as the parent cell

mitochondria small spherical-to rod-shaped organelles found within cells (singular-mitochondrion).

mitochondrial myopathy one of the manifestations of hereditary mitochondrial disorders, occurring as a result of a point mutation in mitochondrial DNA; can also affect other organ systems, particularly the brain.

mitral stenosis pathologic narrowing of the orifice of the mitral valve, commonly the result of rheumatic fever or age related calcification of the valve leaflets. One of the causes of left atrial enlargement.

mitral valve the one-way valve located between the left atrium and the left ventricle.

mixed apnea combination of central and obstructive apnea.

mixed venous blood blood sampled from the pulmonary artery.

mixer a device that blends or mixes two gases to provide a precise mixture (concentration) of the gases.

ml abbreviation for milliliter.

MLT abbreviation for minimal leak technique, a method for determining the cuff inflation volume on endotracheal tubes; during MLT, air is slowly injected into the cuff until the leak stops; once a seal is obtained, a small amount of air is removed, allowing a slight leak at peak inflation pressure

mm abbreviation for millimeter.

mm Hg abbreviation for millimeters of mercury.

MMV abbreviation for mandatory minute ventilation; a mode of ventilatory support. MMV ensures delivery of a preset minimum minute volume, with the patient allowed to breathe spontaneously

mode of ventilation represents a combination of control, phase, and conditional variables that establish a set pattern of spontaneous and/or mandatory breaths.

moderate persistent asthma category of asthma characterized by symptoms of coughing or wheezing on a near daily basis, with exacerbations experienced more than 2 times per week, and often persisting for multiple days; manifests symptoms that routinely interfere with normal daily activities of living or normal nighttime sleep patterns and nocturnal symptoms of coughing, wheezing, or breathlessness more than 1 time per week, plus measured FEV1 or PEF routinely 60% to 80% of predicted or personal best, while consistently maintaining more than 30% variability in PEF rates.

modified Allen test the most common technique to determine the adequacy of ulnar circulation

MODS abbreviation for multiple organ dysfunction syndrome

molar solution solution containing 1 mole (mol) of solute per liter of solution.

molecular sieve a term used to describe components of a type of oxygen concentrator that filters air and chemically removes nitrogen and some trace gases from the air.

mold form of fungus that grows as long multicellular forms called hyphae, which associate to form structures called mycelia.

mole quantity of a substance equal to its gram molecular weight, which contains 6.02 X 1023 atoms (Avogadro's number).

molecular diffusion transport mechanism derived from random thermal oscillation of a molecule; so long as the molecules have a constant temperature, molecular diffusion always occurs and is responsible for gas exchange at the level of the alveolar-capillary membrane.

molecular sieve a crystalline chemical separation device with molecular size pores that adsorbs small but not large molecules

molecular weight weight of a molecule attained by adding the atomic weight of its constituent atoms.

monitored cardiac arrest cardiac arrest in a patient who is being monitored.

monitoring continuous, or nearly continuous, evaluation of the physiologic function of a patient for the purpose of guiding management decisions, including when to make therapeutic interventions and assessment of those interventions.

monitoring lead I the single ECG lead used for monitoring the heart for arrhythmias. Lead I is obtained by attaching the negative electrode to the right arm or the upper right anterior chest wall and the positive electrode to the left arm or the upper left anterior chest wall.

monitoring lead II the single ECG lead commonly used for monitoring the heart solely for arrhythmias. Lead II is obtained by attaching the negative electrode to the right arm or the upper right anterior chest wall and the positive electrode to the left leg or the lower left anterior chest wall at the intersection of the left fifth intercostal space and the midclavicular line.

monitoring lead III the single ECG lead used for monitoring the heart for arrhythmias. Lead III is obtained by attaching the negative electrode to the left arm or the upper left anterior chest wall and the positive electrode to the left leg or the lower left anterior chest wall at the intersection of the fifth intercostal space and the midclavicular line.

monitoring lead MCL1 an ECG lead commonly used in the monitoring of arrhythmias in the hospital, particularly in differentiating supraventricular arrhythmias with aberrant ventricular conduction (aberrancy) from ventricular arrhythmias. Lead MCL1 is obtained by attaching the positive electrode to the right side of the anterior chest in the fourth intercostal space just right of the sternum. The negative electrode is attached to left chest in the midclavicular line below the clavicle.

monitoring lead MCL6 the single ECG lead commonly used for monitoring the heart solely for arrhythmias. Lead MCL6 is obtained by attaching the negative electrode to the upper left anterior chest wall and the positive electrode to the lower left anterior chest wall at the intersection of the sixth intercostal space and the midaxillary line.

Monocyte-Myxoma

monocyte a large, mononuclear leukocyte normally found in lymph nodes, spleen, bone marrow, and loose connective tissue.

monodisperse referring to an aerosol in which particles are of uniform size

monoplace chamber hyperbaric chamber for one person with one lock and compressed with 100% oxygen.

monosaccharide basic unit of the carbohydrate molecule; a simple sugar.

moral philosophy individual's behavioral code, defining behavior in a given situation, based on personal principles the individual has previously adopted.

morbidity the condition of having or being affected by a disease; the rate at which this occurs within a population.

morphine sulfate a narcotic analgesic and sedative used to produce amnesia in conscious patients before cardioversion of certain arrhythmias. Also used as a vasodilator to relieve congestive heart failure secondary to left heart failure.

morphology the study of structures and forms in living things

"M" (or rabbit ears) pattern refers to the rSR' pattern of the QRS complex in V1 representative of a right bundle branch block.

mortality death; the rate at which death occurs within a population.  

motivation patient's interest in changing an undesirable behavior associated with his or her condition.

motor nerve a nerve consisting of efferent fibers that conduct impulses from the brain or the spinal cord to one of the muscles or organs.

mottling a condition of spotting with patches of color

mouth occlusion pressure (PO.1) test of central respiratory drive that is independent of underlying respiratory mechanics; maximum negative mouth pressure generated during the first 100 milliseconds (0.1 seconds) of inspiration measured during complete airway occlusion.

MOV abbreviation for minimal occluding volume; the minimum endotracheal tube cuff pressure needed to prevent gas leakage during a positive pressure inspiration

MSVC abbreviation for maximum sustainable ventilatory capacity

mucociliary of or pertaining to ciliated mucosa mucoid resembling mucus

mucociliary apparatus mechanism that clears inhaled agents from the lower respiratory tract.

mucokinesis the process of moving mucus, that is, therapeutic methods designed to aid in removal of excess or abnormal secretion of the respiratory tract

mucokinetic agent drug, such as acetylcysteine, intended to reduce mucus viscosity and assist with the mobilization of airway secretions.

mucolysis the breaking down of mucus; usually refers to chemical degradation of mucopolysaccharide by certain drug agents called mucolytics

mucolytic a drug agent capable of mucolysis

mucopolysaccharide anyone of a group of polysaccharides containing hexosamine and being the chief constituent of normal mucus

mucoprotein a compound, present in all connective and supporting tissue, that contains polysaccharides combined with protein and is relatively resistant to denaturation

mucopurulent characteristic of a combination of mucus and pus

mucosa the upper layer of tissue lining the airways, including the mucous blanket, epithelium, and lamina propria

mucous pertaining to or resembling mucus; secreting mucus.

mucus the gel-like substance of the mucous membranes, composed of mucin (secreted by the mucus glands), along with various inorganic salts, desquamated cells, and leukocytes.

multifocal indicates an arrhythmia originating in different pacemaker sites (e.g., a ventricular arrhythmia with QRS complexes that differ in size, shape, and direction).

multifocal atrial tachycardia (MAT) an atrial tachycardia that originates in three or more different ectopic pacemaker sites, characterized by P' waves that usually vary in size, shape, and direction in each given lead.

multifocal premature ventricular contractions (PVC's) different-appearing premature ventricular contractions (PVC's) in the same tracing that originate from different ectopic pacemaker sites in the ventricles.

multiform applies to a ventricular arrhythmia with QRS complexes that differ in size, shape, and direction, originating in single or multiple pacemaker sites.

multiform premature ventricular contractions (PVC's) different-appearing premature ventricular contractions (PVC's) in the same tracing that originate in one or more ectopic pacemaker sites in the ventricles.

multiform ventricular tachycardia ventricular tachycardia with QRS complexes that differ markedly from beat to beat.

multiplace chamber a hyperbaric chamber compressed with air and designed for more than one person and with more than one lock (not including a medical lock).

multiple equivalents of resting O2 consumption (METS) an indirect measure of physiological work performed during exercise and stress testing

multiple organ dysfunction syndrome (MODS) a condition in which dysfunction of many different organs occurs, usually accompanying acute lung injury

multiple sclerosis (MS) demyelinating disease of the central nervous system characterized clinically by repeated remissions and exacerbations of symptoms, including paresthesias, motor weakness, diplopia, blurred vision, bladder incontinence, and ataxia.

multiple sleep latency testing (MSLT) test that determines a person's propensity to fall asleep. A mean MSLT of 15 minutes is normal for a well-rested adult; a mean MSLT of less than 5 minutes indicates severe hypersomnia.

multistage reducing valve a pressure reducing valve that has more than one level of pressure reduction between system pressure and working pressure.

Munchausen syndrome by proxy psychiatric disorder in which a caretaking individual, usually a parent, stages and even induces serious illness in his or her child or charge, usually for the purpose of seeking attention and interaction with medical personnel.

murmur extra cardiac sound heard in conjunction with S1 and S2.

muscarinic agent substance that stimulates the postganglionic parasympathetic receptor.

muscle fatigue condition involving a loss of the capacity to develop force and/or velocity of a muscle resulting from muscle activity overload, which is reversible by rest

muscle tremor the cause of extraneous spikes and waves in the ECG brought on by voluntary or involuntary muscle movement or shivering; often seen in elderly persons or in a cold environment.

muscular dystrophy heterogeneous group of progressive, hereditary degenerative skeletal muscle diseases in which the respiratory muscles, like any skeletal muscle, become progressively weak, eventually culminating in respiratory failure and death (respiratory complications are the most common cause of death in these diseases).

mutation a variation or change in genetic structure

mutism a condition of being unable to speak

mutuality characteristic considered essential in nurturing a relationship by agreeing on the problems and the means to resolve them.

mV abbreviation for millivolt.

myalgia muscle pain

myasthenia gravis a disorder of neuromuscular conduction that leads to muscle weakness of the skeletal muscles, particularly those of the face, throat, and respiratory system. Weakness and respiratory failure can occur rapidly as muscle strength decreases with repetitive contraction against a load

Mycobacteria acid-fast microorganisms belonging to the genus Mycobacterium

mycobacterial pneumonia any of a group of pneumonias caused by tuberculous and non-tuberculous mycobacteria (NTM) and diagnosed by acid-fast bacilli (AFB) smears and mycobacterial cultures, using nucleic acid probes to detect Mycobocterium tuberculosis, Mycobocterium avium complex, Mycobocterium gordonae, and/or Mycobocterium kansasii.

Mycoplasma a genus of ultramicroscopic pleomorphic organisms that lack rigid cell walls, grow on artificial media but do not retain the Gram stain, and are able to pass through bacterial filters; a cause of atypical pneumoma

mycosis any fungal disease.

mydriasis dilation of the pupil of the eye  

myelin the substance that constitutes the sheaths of various nerve fibers throughout the body. It is largely composed of fat, giving the fibers a white, creamy color.

myelogram, myelography radiographic study of the spinal cord after the injection of a dye

myocardial pertaining to the muscular part of the heart.

myocardial infarction occlusion of a coronary artery resulting in distal myocardial tissue necrosis, often accompanied by significant complications

myocardial injury reversible changes in the myocardial cells from prolonged lack of oxygen. ECG manifestations include ST elevation or depression over injured myocardial cells.

myocardial ischemia reversible changes in myocardial cells from a temporary lack of oxygen. ECG manifestations include symmetrical T wave elevation or inversion over ischemic myocardial cells.

myocardial necrosis (infarction) irreversible damage to myocardial cells causing their death, the result of prolonged lack of oxygen. ECG manifestations include abnormal Q waves over necrotic myocardial cells.

myocardial (or "working") cells myocardial cells other than those in the electrical conduction system of the ventricles.

myocardial perfusion imaging imaging technique that involves intravenous injection of a radionuclide agent, which accumulates in the myocardium in proportion to regional myocardial perfusion.

myocardial rupture rupture of the myocardial wall, usually occurring in the left ventricle in the area of necrosis following an acute transmural myocardial infarction.

myocarditis an inflammatory condition of the myocardium caused by viral, bacterial, or fungal infection, serum sickness, rheumatic fever, or chemical agents, or as a complication of a collagen disease

myocardium cardiac muscle.

myoepithelial cells spindle-shaped cells found around sweat, mammary, and salivary glands. The myoepithelial cells are contractile and resemble smooth muscle cells.

myofibril tiny structure within a muscle cell that contracts when stimulated. Contains the contractile protein filaments actin and myosin.

myoglobin a ferrous globin complex consisting of one heme group and one globin polypeptide chain. It is responsible for the red pigment seen in skeletal muscle.

myopathy an abnormal condition of skeletal muscle leading to muscle weakness, wasting, and histologic changes in the muscle tissue, as seen in any of the muscular dystrophies

myosin one of the contractile protein filaments in myofibrils that give the myocardial cells the property of contractility. The other is actin.

myxedema a severe form of hypothyroidism characterized by dry swelling and abnormal deposits of mucin in the tissues

myxoma a connective tissue neoplasm that often grows to enormous size