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Bacteria:
single-celled
organisms that can exist independently, symbiotically (in cooperation with
another organism) or parasitically (dependent upon another organism, sometimes
to the detriment of the other organism). Examples of bacteria include
acidophilus (found in yogurt), streptococcus the cause of strep throat, and E.
coli (a normal intestinal bacteria, as well as a disease-causing agent).
Bainbridge reflex: The
increased heart rate that follows increased pressure or distension of the right
atrium.
Balance study:
a nutritional
balance study involves the measurement of the intake of a specific nutrient as
well as the elimination of that nutrient in urine, feces, sweat, etc. If intake
is greater than loss of a particular nutrient the individual is said to be in
"positive balance." If intake is less than loss, an individual is said to be in
"negative balance" for the nutrient of interest.
Ball-and-socket joint: A
synovial joint in which the rounded surface of one bone moves within the
cup-shaped depression or fossa of another bone, as in the shoulder or hip joint.
Also called a spheroid joint.
Basal metabolic rate (BMR):
The rate of metabolism measured under standard or basal conditions considered to
be awake, at rest and fasting)
Bile:
a yellow,
green fluid made in the liver and stored in the gallbladder. Bile may then pass
through the common bile duct into the small intestine where some of its
components aid in the digestion of fat.
Bile acids:
components of
bile, formed by the metabolism of cholesterol. Bile acid deficiency may lead to
the formation of cholesterol gallstones, because bile salts (formed from bile
acids) are required to dissolve cholesterol in bile so that it may be eliminated
via the intestines.
Bioavailable:
the portion
of a nutrient (or other chemical) that can be absorbed, transported, and
utilized physiologically.
Biomarker:
a physical,
functional, or biochemical indicator (e.g., the presence of a particular
metabolite) of a physiological or disease process.
Blood-brain barrier (BBB):
A barrier consisting of specialized brain capillaries and astrocytes that
prevents the passage of materials from the blood to the cerebrospinal fluid in
the brain.
Bone mineral
density (BMD):
a term used
in quantifying the mineralization of bone. The mineral component of bone
consists largely of calcium and phosphorus. BMD is possitively associated with
bone strength and resistance to fracture. BMD can be determined through a low
radiation X-ray technique known as DEXA.
Bone
remodeling:
the
continuous turnover process of bone that includes bone resorption and bone
formation. An imbalance in the regulation of bone remodeling's two contrasting
events, bone resorption and bone formation, increases the fragility of bone and
may lead to osteoporosis.
Buffer:
a chemical
used to maintain the pH of a system by absorbing hydrogen ions (which would make
it more acidic) or absorbing hydroxyl ions (which would make it more alkaline).
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