# – A
5-alpha reductase: An enzyme that converts testosterone
to dihydrotestosterone. The latter stimulates prostate growth.
abdominoplasty (tummy tuck): A
procedure to remove excess skin on the abdomen
and tighten the underlying muscle and inner girdle.
Often combined with liposuction.
abduction: Movement of a body
part away from the midline.
ablative: Describes skin-resurfacing
procedures that remove surface skin layers, in
contrast to non-ablative procedures.
acetabulum: The socket of the
hip’s ball-and-socket joint, part of the
pelvic bone.
acetylcholine: A chemical neurotransmitter
that plays a role in attention, learning, and
memory by helping brain cells communicate with
each other.
Achilles’ tendon: A band
of connective tissue that runs up the back of
the heel; susceptible to inflammation and rupture.
acquired immunodeficiency syndrome (AIDS): A
disease resulting from infection with the human
immunodeficiency virus (HIV). AIDS develops when
a subset of T cells, the target of HIV, is so
diminished that the body is no longer able to
fight off pathogens. Most HIV-infected individuals
ultimately succumb to infections.
acquisition: The first step
in memory formation, in which the brain absorbs
new information.
acute pain: Pain that is usually
caused by an injury or trauma and doesn’t
persist.
acute urinary retention: An
inability to squeeze any urine past the enlarged
prostate because the bladder has become distended
and its muscular wall has weakened.
adaptive immunity: The response
of antigen-specific lymphocytes to antigens.
After the first response of lymphocytes to a
pathogen, memory B and T cells remain to fight
more effectively against the pathogen if it ever
returns.
adduction: Movement of a body
part toward or across the midline.
adenocarcinoma: Cancerous tumor
that grows in the epithelial cells lining the
inner surface of an organ, particularly the colon
or rectum.
adenoma: Benign tumor arising
in the epithelial cells lining the inner surface
of an organ. Most commonly found in the colon.
adenosine triphosphate (ATP): The
molecule that carries energy for all cells.
adequate intake (AI): An estimate
for the nutritional needs of healthy people used
when there are not enough data to support an
RDA.
adjuvant therapy: Treatment
such as chemotherapy, hormonal therapy, or radiation
used following surgery to cure, reduce, or control
cancer.
adrenal glands: Two glands
(one on top of each kidney) that secrete the
hormones cortisol and norepinephrine.
adrenaline and noradrenaline: Also
called epinephrine and norepinephrine, these
key stress hormones cause a cascade of physiological
responses in the body, such as faster heartbeat
and respiration, a rise in blood pressure, and
the release of energy-boosting fats and glucose.
adult day services: Community-based
centers, usually open during working hours, to
help people who need supervision, social support,
or assistance with daily activities.
adulterant: An unintended ingredient
in a medicinal product (herb, supplement, or
prescription drug).
advance care directive (or advance medical
directive): A document that describes
your wishes and goals for health care should
you be unable to express them yourself.
advance directive for health care: A
legal document that describes a person’s
wishes for health care and end-of-life decisions
if he or she becomes too sick or incapacitated
to express them.
advanced sleep phase syndrome: A
daily sleep/wake rhythm in which the onset of
sleep and the time of awakening are earlier than
desired; the person progressively wakes up earlier
and wants to retire earlier each day.
aerophagia: Excessive swallowing
of air.
age-related cognitive decline: The
slight loss of memory and speed of information
processing that occurs with normal aging.
age-related macular degeneration (AMD): A
potentially blinding condition that destroys
a tiny part of the retina called the macula,
which gives you sharp central vision.
agoraphobia: Fear and avoidance
of open spaces and public spaces.
albumin: A protein that is
detectable by urinalysis or a simple blood test;
abnormal levels may indicate kidney damage.
aldosterone: A hormone secreted
by the adrenal glands that signals the kidneys
to conserve sodium and water; the result is higher
blood pressure.
alimentary canal: Another term
for the gastrointestinal tract or the digestive
tract.
allergen: A harmless substance
that triggers the immune system to mount an inappropriate
response known as an allergic reaction.
allergic reaction: An excessive
inflammatory reaction to a harmless antigen.
Also known as a hypersensitivity reaction.
allergic: Having an overly
sensitive immune response to one or more harmless
substances. (See atopic.)
allergy: The mounting of inappropriate
immune responses to one or more harmless substances.
The result is the onset of an excessive inflammatory
reaction.
alpha cells: Cells that secrete
the hormone glucagon; located in the islets of
Langerhans of the pancreas.
amnesia: A condition caused
by brain injury or illness and characterized
by an inability to form new long-term memories
or to remember earlier ones.
amygdala: A brain structure
with strong connections to the hippocampus and
other structures of the limbic system that is
vital to emotional arousal and the formation
of long-term memories.
anal canal: The last inch of
the rectum before it opens to the outside of
the body.
analgesics: Drugs or substances
that reduce or eliminate the sensation of pain.
anaphylaxis: A severe, potentially
life-threatening systemic hypersensitivity reaction.
Also called anaphylactic shock or allergic shock.
androgens: Primarily male steroid
hormones that are produced in the adrenal glands
and ovaries in women.
anemia: A decline in the number
of red blood cells or the amount of hemoglobin
in the blood, which lowers the oxygen-carrying
capacity of the blood. It can lead to fatigue.
anesthesia: A general loss
of sensation. An anesthetic is a drug or substance
that produces a loss of sensation.
aneurysm: A large pocket or
bubble in a blood vessel that forms a weak spot
in the vessel’s wall, which can be life-threatening
if it ruptures; some people may have a genetic
tendency to develop aneurysms.
angina: Chest pain or discomfort
that develops when the heart muscle isn’t
getting enough oxygen and blood; also known as
angina pectoris.
angioplasty: A procedure used
to widen narrowed arteries, most commonly by
inserting a thin tube, or catheter, into the
affected artery and inflating a balloon.
angiotensin: A protein that
increases blood pressure by constricting blood
vessels and stimulating the release of aldosterone.
The inactive form is angiotensin I, and the active
form is angiotensin II.
ankylosing spondylitis: An
inflammatory disease of the spine that often
leads to pain and stiffness of the spine.
annulus fibrosus: The multilayered,
fibrous outer portion of an intervertebral disk.
annulus: The tough outer covering
of a disk.
anterior chamber: The space
behind the cornea and in front of the iris; it
is filled with aqueous humor.
antibodies: Molecules produced
by plasma cells, the descendants of B cells.
When foreign molecules enter the body, antibodies
swiftly travel to potential trouble spots where
they use various strategies to stop the spread
of infection.
anticoagulants: Drugs used
to reduce blood’s clotting ability.
anticonvulsants: Drugs used
to treat seizures; some are also helpful in treating
some pain conditions.
antidepressant: A drug used
to combat depression.
antigen: A foreign protein
or carbohydrate complex that causes an immune
response.
antigen-presenting cells: A
group of cells involved in the innate and adaptive
immune responses. Antigen-presenting cells, especially
dendritic cells, present antigens to B and T
cells, thereby stimulating the adaptive immune
response. Macrophages are also antigen-presenting
cells.
antihistamines: Drugs that
block the action of histamine, thereby dampening
the ferocity of an immediate allergic reaction.
antihypertensives: Medications
used to treat high blood pressure.
antileukotrienes: Drugs that
block the action of leukotrienes. Used in the
treatment of asthma and allergic rhinitis. Also
known as leukotriene modifiers.
antimicrobial: An agent that
acts against bacteria, fungi, and parasites in
the body.
antioxidant: A substance that
helps protect the body against destructive free
radicals and other unstable molecules by giving
up electrons. Antioxidant micronutrients include
beta carotene and other carotenoids, vitamin
C, and vitamin E.
antiplatelets: Medications
that interfere with blood clotting by inhibiting
the activity of platelets.
antipsychotic: A drug used
to treat psychotic symptoms, such as disordered
thoughts, delusions, or hallucinations.
antispasmodic (spasmolytic): An
agent that relieves smooth muscle spasms.
antithyroid drugs: A class
of drugs that are sometimes prescribed to block
the thyroid gland’s ability to make hormone,
thus reducing the level of thyroid hormone in
your body.
aorta: The main artery that
carries blood from the heart.
aphasia: Difficulty speaking
or comprehending language; a common occurrence
after a stroke affecting the left hemisphere
of the brain, where language is processed.
apnea: See sleep apnea.
apolipoproteins: Proteins that
combine with cholesterol and triglyceride to
form lipoproteins.
apoptosis: A process of programmed
cell death in which redundant or flawed cells
destroy themselves.
aqueous humor: The watery fluid
that nourishes the eye and fills the anterior
and posterior chambers.
arrhythmia: An abnormal heart
rhythm caused by a disturbance in the heart’s
electrical system. Can cause dizziness and fainting,
in turn increasing the risk of falling. Severe
arrhythmias can be deadly.
arterial resistance: The pressure
that the artery walls exert on blood flow; in
general, the less elastic the arteries, the greater
the arterial resistance and the higher the blood
pressure.
arteriovenous malformation: An
abnormal tangle of blood vessels in which the
arteries feed directly into the veins.
artery: A blood vessel that
carries blood away from the heart.
arthritis: Inflammation of
a joint, often with destruction of cartilage.
There are over 100 different types of arthritis.
arthrodesis: fusion of two
bones to reduce pain and provide stability to
a damaged, arthritic, or painful joint.
arthroplasty: Joint replacement.
arthroscopy: The use of miniature
scopes and other small instruments inserted through
small incisions to diagnose and repair joint
problems.
articular cartilage: Tough,
rubbery tissue that forms on the surface of bones
within joints.
articular processes: The two
upper and two lower bony projections on the back
part of each vertebra, which form the facet joints.
aspiration: The use of a hollow
needle and syringe to suction out fluid or cells
from a cyst or tumor.
assisted living: Generally,
single rooms or small apartments set up to encourage
independent living while offering certain services,
such as meals, transportation, or assistance
with daily living tasks.
asthma: A chronic inflammatory
disease of the airways that typically starts
in childhood, although some people develop asthma
later in life.
astigmatism: A refractive error
characterized by irregular curvature of the cornea
or lens, causing distorted images.
astringent: An agent that contracts
skin tissues.
atherosclerosis: Development
of cholesterol-rich plaque on the inner walls
of arteries, which can eventually obstruct blood
flow; the disease responsible for most heart
attacks and many strokes.
atherosclerotic plaque: A cholesterol-rich
deposit on an artery wall.
atherothrombotic stroke: A
type of stroke that occurs when a large artery
to the brain, already narrowed by atherosclerosis,
is completely blocked by the formation of a clot.
athlete’s foot: A fungal
infection that causes a moist, itchy rash, usually
between the toes or on the sole of the foot.
atlas: Another name for the
C-1 vertebra of the neck, which lies just beneath
the skull.
atopic dermatitis (eczema): A
chronic inflammatory skin condition that usually
initially appears in young children who have
an inherited predisposition to allergies. Many
children with atopic dermatitis go on to develop
atopic (allergic) rhinitis or atopic (allergic)
asthma.
atopic rhinitis: A seasonal
or year-round allergic condition marked by sneezing,
runny nose, and congestion. The most common type
of allergy, it is caused by an IgE-mediated immune
response.
atopic: Having an inherited
predisposition to allergies. The term is often
used interchangeably with “allergic,” although
not all allergies have a genetic component.
atopy: The inherited tendency
to develop allergies. The three major atopic
diseases are atopic rhinitis, atopic asthma,
and atopic dermatitis.
atrial fibrillation: A common
heart rhythm disturbance in which the atria quiver
ineffectually, allowing blood to pool in the
left atrium and form clots that may travel to
the brain and cause an embolic stroke.
atypical lobular hyperplasia: Abnormally
shaped cells multiplying excessively in the normal
tissue of a breast lobule.
audiogram: A graph showing
the shape, or nature, of your hearing loss as
measured by a complete hearing evaluation.
audiologist: A health professional
who assesses hearing and balance, as well as
fits and dispenses hearing aids.
auditory nerve: The nerve in
the inner ear that receives electrical signals
from the hair cells and relays them to the brain.
Also known as the eighth cranial nerve.
aura: Neurological symptoms,
such as flashing lights or a blind spot, that
may precede a migraine headache.
autoimmune disease: A disease
in which the immune system attacks the body’s
tissues as if they were foreign. There are more
than 80 autoimmune diseases.
autoimmune disorder: a condition
stemming from an abnormal immune response generated
by the body against its own tissues, cells, or
molecules.
autonomic nervous system: The
part of the nervous system that controls such
involuntary body functions as breathing, blood
pressure, heartbeat, and the dilation or constriction
of arteries and small airways in the lungs. Includes
the sympathetic and parasympathetic nervous systems.
autonomic neuropathy: Nerve
damage that affects the autonomic nervous system,
which controls digestive, bladder, bowel, cardiac,
and sexual function.
axillary: The area or cavity
beneath the junction of the arm and body. Better
known as the armpit.
axis: Another name for the
C-2 vertebra of the neck, which lies just beneath
C-1.
axon: A long filament-like
projection of a neuron that conducts electrical
signals away from the neuron cell body (nucleus)
to other neurons. |
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