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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.
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