| Macula |
the
area of the retina that allows fine details to be observed
at the center of vision; also refers to any small, flat spot
on the skin |
| Macular
degeneration |
gradual
loss of vision due to deterioration of nerve tissue in the
retina |
| Magnesium |
a
mineral that is essential for many body functions, including
nerve impulse transmission, formation of bones and teeth,
and muscle contraction |
| Magnetic
resonance imaging (MRI) |
a
technique that uses magnetic fields and radio waves to create
high-quality cross-sectional images of the body without using
radiation |
| Malabsorption |
an
impaired ability of the lining of the small intestine to absorb
nutrients from food |
| Malaria |
a
parasitic disease spread by mosquitos that causes chills and
fever; potentially fatal complications in the liver, kidneys,
blood, and brain are possible |
| Malformation |
abnormal
development of an organ or tissue |
| Malignant |
a
word used to describe a condition that is characterized by
uncontrolled growth and/or that can be fatal, such as a cancerous
tumor |
| Malignant
hyperthermia |
a
reaction to certain anesthesia gases involving intense muscle
contractions and a high fever |
| Malignant
melanoma |
the
most serious type of skin cancer, in which a mole changes
shape, darkens, becomes painful, and/or bleeds easily |
| Mallory-Weiss
syndrome |
a
condition associated with alcoholism in which the lower end
of the esophagus tears, causing vomiting of blood |
| Mammography |
an
X-ray procedure done to detect breast cancer |
| Mammoplasty |
a
general term for a cosmetic operation on the breasts; includes
breast reduction, enlargement, and reconstruction after a
mastectomy |
| Mandible |
another
term for the lower jaw |
| Mania |
a
mental disorder characterized by extreme excitement, happiness,
overactivity, and agitation; usually refers to the high of
the highs and lows experienced in manic-depressive disorder |
| Manic-depressive
disorder |
a
mental disorder characterized by extreme mood swings, including
either mania, depression, or a continuing shift between the
two extremes |
| MAO
inhibitor |
see
Monoamine oxidase inhibitor antidepressant |
| Marfan's
syndrome |
a
rare genetic disorder that affects connective tissue, leading
to abnormalities of joints, bones, tendons, ligaments, arteries,
and/or the heart |
| Mast
cell |
a
type of cell present in most body tissues that releases substances
in response to an allergen, which causes symptoms such as
inflammation |
| Mastectomy |
a
surgical procedure in which all or part of the breast is removed
to prevent the spread of cancer |
| Mastitis |
inflammation
of the breast, which is usually caused by a bacterial infection |
| Maxilla |
one
of two bones that form the upper jaw, the roof of the mouth,
and the center portion of the face |
| Measles |
an
illness caused by a viral infection, causing a characteristic
rash and a fever; primarily affects children |
| Meconium |
thick,
sticky, greenish-brown stool passed by a postmature fetus,
or one experiencing fetal distress, into the amniotic fluid,
or by an infant during the first couple of days after birth |
| Medial |
a
term used to describe something situated on or near the midline
of the body or a body structure |
| Median
nerve |
a
nerve running down the arm to the hand; controls muscle movement
in the forearm and hand and conveys sensation from part of
the hand |
| Mediastinoscopy |
investigation
of the central chest compartment using an endoscope that is
inserted through an incision in the neck |
| Medulla |
the
center part of an organ or body structure; sometimes used
to refer to the lower part of the brain stem |
| Medulloblastoma |
a
type of cancerous tumor, occurring in the section of the brain
that controls posture and balance; found mainly in children |
| Megacolon |
a
severely swollen large intestine, causing severe constipation
and abdominal bloating; may be present at birth or develops
later |
| Megaloblastic
anemia |
a
type of anemia in which a lack of the vitamin B12 or folic
acid interferes with red blood cells and causes them to be
enlarged and deformed, resulting in tiredness and weight loss |
| Meiosis |
the
type of cell division that occurs only in the ovaries and
testicles, producing cells with half the genes of the original
cell; these cells then form eggs and sperm |
| Melanin |
the
pigment that gives skin, hair, and eyes their coloring |
| Melanocytes |
cells
that produce the pigment melanin |
| Melanocyte-stimulating
hormone |
a
hormone that coordinates pigmentation of the skin, eyes, and
hair |
| Melanoma |
a
skin tumor composed of cells called melanocytes |
| Menarche |
the
beginning of menstruation |
| Meniere's
disease |
a
disorder of the inner ear, causing hearing loss, ringing in
the ear, and the sensation that one's surroundings are spinning |
| Meninges |
the
three membranes that surround and protect the spinal cord
and brain |
| Meningioma |
a
rare noncancerous tumor developing in the protective membranes
covering the brain called the meninges; can cause headaches
and problems with vision and mental function |
| Meningitis |
inflammation
of the meninges; usually caused by infection by a microorganism
(meningitis caused by bacteria is life-threatening; viral
meningitis is milder) |
| Meningocele |
a
protrusion of the meninges through an opening in the skull
or spinal cord due to a genetic defect |
| Meniscectomy |
surgical
removal of all or part of a cartilage disk from a joint |
| Meniscus |
a
crescent-shaped pad of cartilage in joints that helps to reduce
friction |
| Menopause |
the
period in a woman's life when menstruation stops, resulting
in a reduced production of estrogen and cessation of egg production |
| Menorrhagia |
excessive
loss of blood during menstruation, which can be caused by
disorders of the uterus |
| Menstrual
cycle |
the
periodic discharge of blood and mucosal tissue from the uterus,
occurring from puberty to menopause in a woman who is not
pregnant |
| Menstruation |
the
shedding of the lining of the uterus during the menstrual
cycle |
| Mesenteric
infarction |
death
of tissue in the intestine due to lack of blood supply to
that tissue |
| Mesenteric
lymphadenitis |
inflammation
of lymph nodes in an abdominal membrane |
| Mesothelioma |
a
cancerous tumor occurring in the lining of the lungs and chest
cavity, often associated with exposure to asbestos dust |
| Mesothelium |
a
tissue layer that lines the heart, abdomen, chest cavity,
and lungs |
| Messenger
RNA |
an
RNA molecule that transports the information stored in DNA
out of a cell's nucleus in order to make proteins |
| Metabolic
rate |
the
speed at which the body uses energy |
| Metabolism |
a
general term for all of the chemical processes that occur
in the body |
| Metabolite |
any
substance that takes part in a chemical reaction in the body |
| Metastasis |
the
spreading of a cancerous tumor to another part of the body
through lymph, blood, or across a cavity; also sometimes refers
to a tumor that has been produced in this way |
| Metered-dose
inhaler |
an
inhaler that gives a specific amount of medication with each
use |
| Microbe |
another
term for a microorganism, especially one that causes disease |
| Microbiology |
the
study of microorganisms |
| Microcephaly |
an
abnormally small head |
| Microdiskectomy |
surgical
removal of the protruding part of a prolapsed disk |
| Microorganism |
any
tiny, single-celled organism (such as a bacterium, virus,
or fungus) |
| Microsurgery |
a
surgical technique that uses a special binocular microscope
to operate on tiny, delicate, or hard-to-reach tissues |
| Micturition
syncope |
fainting
or feeling weak while standing at the toilet; caused by an
abnormal heartbeat or a drop in blood pressure |
| Middle
ear |
the
small cavity between the eardrum and inner ear; contains three
tiny, linked bones that transmit sound to the inner ear |
| Middle
ear effusion |
the
buildup of fluid in the middle ear, which can affect hearing
|
| Midwifery |
a
profession concerned with providing care to a mother and baby
during pregnancy and childbirth |
| Migraine |
a
severe headache, usually accompanied by vision problems and/or
nausea and vomiting, and that typically recurs |
| Mineral |
a
substance that is a necessary part of a healthy diet (such
as potassium, calcium, sodium, phosphorus, and magnesium) |
| Minipill |
an
oral contraceptive containing only the synthetic hormone progesterone
(birth control pills contain estrogen and progesterone) |
| Miotic |
a
drug that causes the pupil to constrict |
| Miscarriage |
expulsion
of a fetus before it has developed sufficiently to survive
on its own |
| Mites |
small
eight-legged animals, many of which burrow and feed on blood |
| Mitosis |
the
process by which most cells divide in order to reproduce |
| Mitral
insufficiency |
a
problem with the ability of the mitral valve in the heart
to close, which causes the heart to pump harder and reduces
its efficiency |
| Mitral
stenosis |
a
condition in which the mitral valve in the heart becomes narrowed,
making the heart work harder to pump blood; can lead to symptoms
such as shortness of breath |
| Mitral
valve |
the
valve in the heart that allows blood to flow from the left
atrium to the left ventricle, but prevents blood from flowing
back in |
| Mitral
valve prolapse |
a
common condition in which the mitral valve in the heart is
deformed, causing blood to leak back across the valve; characterized
by a heart murmur and sometimes chest pain and disturbed heart
rhythm |
| Modified
radical mastectomy |
a
treatment for breast cancer in which the entire breast, a
section of the chest muscle, and lymph nodes in the chest
and underarm are removed |
| Molar
tooth |
large,
strong teeth at the back of the jaw, primarily used to grind
food |
| Mole |
a
brown to dark-brown spot on the skin that can be flat or raised |
| Molecule |
the
smallest unit of a substance that possesses its characteristics |
| Molluscum
contagiosum |
a
viral infection that causes white bumps on the skin; usually
clears up in a few months |
| Mongolian
spot |
a
brown to blue-black spot on the lower back and buttocks at
birth, caused by a concentration of pigment-producing cells;
usually disappears by the age of 3 or 4 years |
| Monoamine
oxidase inhibitor antidepressant |
a
substance that works by stopping an enzyme that breaks down
stimulating chemicals in the brain; used to treat depression |
| Monoclonal
antibodies |
an
antibody that is produced in the laboratory so that it will
react with only one specific foreign protein; used to help
diagnose certain kinds of cancer |
| Mononucleosis |
an
infection caused by a virus that invades a type of white blood
cell called a monocyte, causing fever, sore throat, and swollen
lymph nodes |
| Monounsaturated
fat |
a
type of fat that is thought to be beneficial in the prevention
of coronary heart disease; found in foods such as olive oil
and peanut oil |
| Morbidity |
the
state of being ill or having a disease |
| Morning
sickness |
nausea
and vomiting experienced early in a pregnancy, affecting about
half of all pregnant women |
| Mortality |
the
death rate, measured as the number of deaths per a certain
population; may describe the population as a whole, or a specific
group within a population (such as infant mortality) |
| Motor
nerve |
a
nerve that carries messages to a muscle that cause the muscle
to contract |
| Motor
neuron disease |
degeneration
of the nerves in the spinal cord and brain that are responsible
for muscle movement, causing weakness and muscle deterioration
|
| Mouth-to-mouth
resuscitation |
a
method of artificial breathing in which someone rhythmically
forces air into the lungs of a person who has stopped breathing
|
| MRI |
see
Magnetic resonance imaging |
| MS |
see
Multiple sclerosis |
| Mucocele |
a
sac or body cavity that is swollen because of the production
of mucus by the cells in its lining |
| Mucolytic |
a
drug that lessens the sticky quality of phlegm and makes it
easier to cough up |
| Mucous
membrane |
the
soft, pink layer of cells that produce mucus in order to keep
body structures lubricated; found in structures such as the
eyelids, respiratory tract, and urinary tract |
| Mucus |
a
slippery fluid produced by mucous membranes that lubricates
and protects the internal surfaces of the body |
| Multi-infarct
dementia |
dementia
caused by multiple strokes |
| Multiple-gated
acquisition scan |
a
technique for evaluating heart efficiency by measuring blood
flow into and out of the heart |
| Multiple
myeloma |
a
cancer that causes uncontrolled production of white blood
cells in the bone marrow |
| Multiple
pregnancy |
the
presence of more than one fetus in the uterus, such as occurs
with twins |
| Multiple
sclerosis |
a
disease in which the protective coverings (myelin) of nerve
fibers in the brain are gradually destroyed; symptoms vary
from numbness to paralysis and loss of control of bodily function |
| Mumps |
a
viral infection that causes inflammation of salivary glands;
primarily affects children |
| Murmur |
a
characteristic sound (heard through a stethoscope) of blood
flowing irregularly through the heart; can be harmless or
may be an indication of disease |
| Muscle
fibers |
specialized,
contracting cells that are bundled together to form muscles |
| Muscle
relaxants |
a
group of drugs used to relieve muscle spasm and to treat conditions
such as arthritis, back pain, and nervous system disorders
such as stroke and cerebral palsy |
| Muscle
tone |
the
natural tension in resting muscles |
| Muscle
wasting |
the
degeneration of a muscle (loss of bulk), caused by disease
or starvation |
| Muscular
dystrophy |
a
rare genetic disorder in which muscles degenerate gradually
and strength is lost |
| Mutagen |
anything
that can increase the rate of abnormal change in cells, which
can lead to cancer |
| Mutation |
a
change in the genetic information within a cell |
| Myalgia |
the
medical term for muscle pain |
| Myasthenia
gravis |
a
disease in which the muscles, mainly those in the face, eyes,
throat, and limbs, become weak and tire quickly; caused by
the body's immune system attacking the receptors in the muscles
that pick up nerve impulses |
| Mycobacterium |
a
type of slow-growing bacterium; resistant to the body's defense
mechanisms and are responsible for diseases such as tuberculosis
and leprosy |
| Mycoplasma |
the
smallest free-living microorganisms |
| Mycosis |
any
disease caused by a fungus |
| Mydriatic |
a
drug that causes the pupil to dilate (widen) |
| Myelin
sheath |
the
fat and protein-containing material that surrounds and protects
some nerves |
| Myelitis |
inflammation
of the spinal cord, which can cause headaches, fever, muscle
stiffness, pain, weakness, and eventually paralysis |
| Myelocele |
protrusion
of the spinal cord and its coverings out from the spine; one
of the more severe forms of spina bifida |
| Myeloma |
a
cancer affecting cells in the bone marrow; sometimes used
as an abbreviation for multiple myeloma |
| Myelosclerosis |
buildup
of fibrous connective tissue in the bone marrow, affecting
the production of blood components |
| Myocardial
infarction |
the
death of an area of heart muscle as a result of being deprived
of its blood supply; characterized by severe pain in the chest;
commonly called a heart attack |
| Myocarditis |
inflammation
of the heart muscle, which can be caused by a virus, certain
drugs, or radiation therapy |
| Myocardium |
the
medical term for heart muscle |
| Myomectomy |
the
surgical removal of a noncancerous tumor from muscle |
| Myopathy |
a
muscle disease, usually one that results in the deterioration
of muscle |
| Myopia |
the
medical term for nearsightedness |
| Myositis |
muscle
inflammation, causing pain and weakness |
| Myringotomy |
a
surgical opening in the eardrum that allows for drainage |
| Myxoma |
a
noncancerous tumor made of mucous material and fibrous connective
tissue |
