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Macrorestriction map
Map depicting the order of and distance between sites at which restriction enzymes cleave chromosomes.
Magnetic field therapy
Using an alternating magnetic field to generate an electric current inside the tissues, resulting in changes to blood flow.
Magnetic Resonance Imaging
The use of nuclear magnetic resonance of protons to produce cross-sectional proton density images of internal structures of the human body.
Magnetic resonance imaging (MRI)
A non-invasive procedure that produces two-dimensional view of an internal organ or structure, especially the brain and spinal cord.
Malabsorption Syndrome
Syndromes resulting from impaired absorption of nutrients from the bowel.
Malabsorption syndromes
Conditions that happen when the small intestine cannot absorb nutrients from foods.
Malaise
A feeling of general discomfort or uneasiness, an out-of-sorts feeling, often the first indication of an infection or other disease.
Malignant
Cancerous.
Malignant tumor
A mass of cancer cells that may invade surrounding tissues or spread to distant areas of the body.
Mallet finger
Common condition due to the rupture of the long extensor tendon of the finger.
Malocclusion
An orthodontic problem that means 'bad bite,' including crowded, missing, or crooked teeth, extra teeth, or a misaligned jaw.
Mammogram
A low-dose x-ray of the breast.
Mammogram
An x-ray of the breast.
Manometry
Tests that measure muscle pressure and movements in the gastrointestinal (GI) tract.
Mapping
See gene mapping, linkage map, physical map.
Marker
A gene with a known location on a chromosome and a clear-cut phenotype, used as a point of reference when mapping a new mutant.
Massage
Mechanical form of therapy in which the soft tissues are made more pliable with different techniques, promoting increased blood flow and subsequent healing.
Mast cells
Cells, which synthesize and store histamines, found in most body tissues, particularly just below the epithelial surfaces, serous cavities and around blood vessels.
Mastitis
Infection of the milk ducts in the breast.
Mastoid
Back portion of the temporal bone behind the ear.
Mastoid surgery
Surgical procedure to remove an infection from the mastoid bone.
Mb
See megabase.
McMurray test
Test for assessing the knee for the presence of a medial meniscal lesion.
Meal plan
A guide to help people get the proper amount of calories, carbohydrates, proteins, fats, vitamins, minerals, and fiber in their diet. (See also food exchanges.)
Mean blood pressure
Average blood pressure, taking account of the rise and fall that occurs with each heartbeat. It is often estimated by multiplying the diastolic pressure by two, adding the systolic pressure, and then dividing this sum by three.
Median nerve
Large nerve, comprising segments from the cervical spine, that is involved in neural function of the upper limb; commonly entrapped in the carpal tunnel of the wrist, to create carpal tunnel syndrome.
Megabase (MB)
Unit of length for DNA fragments equal to 1 million nucleotides and roughly equal to 1 cM.
Megacolon
Huge, swollen colon; results from severe constipation. (See also Hirschsprung�s disease.)
Meige syndrome
A movement disorder that can involve excessive eye blinking (blepharospasm) with involuntary movements of the jaw muscles, lips, and tongue.
Meiosis
The doubling of gametic chromosome number. Meiosis results in four rather than two daughter cells, each with a haploid set of chromosomes.
Melanocytes
Cells in the skin that produce and contain the pigment called melanin.
Melanoma
Cancer of the cells that produce pigment in the skin. Melanoma usually begins in a mole.
Melena
Blood in the stool.
Meniscus
A part of the cartilage in the knees and other joints.
Messenger RNA (MRNA)
RNA that serves as a template for protein synthesis. (See genetic code.)
Metaphase
A stage in mitosis or meiosis during which the chromosomes are aligned along the equatorial plane of the cell.
Metastasis
The spread of cancer from one part of the body to another. Cells in the metastatic (secondary) tumor are like those in the original (primary) tumor.
Micrographia
A change in handwriting with the script becoming smaller and more cramped.
Middle ear
Part of the ear that includes the eardrum and three tiny bones of the middle ear, ending at the round window that leads to the inner ear.
Minimally invasive surgery
Any technique involved in surgery that does not require a large incision. (See also endoscopy, abdominoscopy, or laparoscopy.)
Miosis
Constriction of the pupil.
Misarticulation
Inaccurately produced speech sound (phoneme) or sounds.
Miscarriage
Spontaneous termination of a pregnancy before the fetus has developed enough to survive outside the uterus.
Missense mutation
A change in the base sequence of a gene that alters or eliminates a protein.
Mitochondrial DNA
The mitochondrial genome consists of a circular DNA duplex, with 5 to 10 copies per organelle.
Mitosis
The process of nuclear division in cells that produces daughter cells that are genetically identical to each other and to the parent cell.
Mitral valve
The valve that controls blood flow between the left atrium and left ventricle in the heart.
Modified radical mastectomy
The removal of the breast, some lymph nodes in the armpit, and sometimes part of the chest wall muscles.
Molecule
A group of atoms arranged to interact in a particular way; one molecule of any substance is the smallest physical unit of that particular substance.
Monoamine oxidase (MAO)
An enzyme that makes nervous system hormones inactive.
Monoclonal antibodies
Substances that can locate and bind to cancer cells wherever they are in the body. They can be used alone, or they can be used to deliver drugs, toxins, or radioactive material directly to the tumor cells.
Monoclonal antibodies
Substances that can locate and bind to cancer cells wherever they are in the body.
Monounsaturated fats
Dietary fats, such as olive oil or canola oil, that do not seem to have any affect on blood cholesterol.
Morton's neuroma
Painful condition of one of the digital branches of the plantar nerves in the foot.
Motility
Movement of food through the digestive tract.
Motion sickness
Dizziness, sweating, nausea, vomiting, and generalized discomfort experienced when an individual is in motion.
Motor speech disorders
Group of disorders caused by the inability to accurately produce speech sounds (phonemes).
Moxibustion
The burning of herbal leaves on or near the body.
MRI
A procedure using a magnet linked to a computer to create pictures of areas inside the body. Also called magnetic resonance imaging.
mRNA
See messenger RNA.
Mucosal lining
Lining of gastrointestinal (GI) tract organs that makes mucus.
Mucosal protective drugs
Medicines that protect the stomach lining from acid.
Mucous colitis
See irritable bowel syndrome (IBS).
Mucus
Clear liquid made by the intestines that coats and protects tissues in the gastrointestinal tract.
Multifactorial
A characteristic influenced in its expression by many factors, both genetic and environmental.
Multifidus
Deep lumbar spine muscle that stabilizes the lumbar spine.
Multiple Chemical Sensitivity Disorder
A controversial diagnosis of an allergy-like sensitivity to an unusually broad range and number of substances. This condition has not been subjected to rigorous scientific scrutiny, and there is considerable doubt as to whether or not it actually exists.
Multiple Sclerosis
A slowly progressive central nervous system disease characterized by disseminated patches of demyelination in the brain and spinal cord.
Murmur
A blowing or rasping sound heard while listening to the heart; may or may not indicate problems within the heart or circulatory system.
Musculoskeletal system
The complex system that includes the bones, joints, ligaments, tendons, muscles, and nerves.
Mutation
A change in the number, arrangement, or molecular sequence of a gene.
Myalgic Encephalomyelitis
A synonym for chronic fatigue syndrome in common usage in the United Kingdom and Canada.
Mycoplasma
Very common sexually transmitted disease or urinary tract infection caused by a bacteria-like organism in the urethra and reproductive system.
Mydriasis
Dilation of the pupil.
Myelogram
A specific x-ray study that uses an injection of a dye or contrast material into the spinal canal to allow careful evaluation of the spinal canal and nerve roots.
Myocardial infarction (HEART ATTACK)
Occurs when one of more regions of the heart muscle experience a severe or prolonged decrease in oxygen supply caused by a blocked blood flow to the heart muscle.
Myocardial ischemia
Insufficient blood flow to part of the heart.
Myocardium
The muscle wall of the heart.
Myoclonus
Jerking, involuntary movements of the arms and legs; may occur normally during sleep.
Myofascial pain
The most common form of temporomandibular disorder; discomfort or pain in the muscles that control jaw function and the neck and shoulder muscles.
Myofascial trigger point
Areas of focal muscle tenderness and spasm.
Myoglobin
The oxygen-transporting protein of muscle, resembling blood hemoglobin in function.
Myomectomy
Surgical procedure done to remove fibroids from the uterus while leaving the uterus intact.
Myopia
Nearsightedness.
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