| branched-chain amino acids | Amino acids
with a branching carbon backbone, these are
leucine, isoleucine, and valine. All are essential
amino acids.
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| nonessential amino acids | Amino acids
that can be synthesized by a healthy body in
sufficient amounts; there are 11 nonessential
amino acids. These are also called dispensable
amino acids.
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| semiessential amino acids | Amino acids
that, when consumed, spare the need to use
an essential amino acid for their synthesis.
Tyrosine in the diet, for example, spares the
need to use phenylalanine for tyrosine
synthesis. Also called conditionally essential
amino acids.
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| essential amino acids | The amino acids
that cannot be synthesized by humans in
sufficient amounts or at all and therefore
must be included in the diet; there are nine
essential amino acids. These are also called
indispensable amino acids.
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| high-quality (complete) proteins | Dietary
proteins that contain ample amounts of all
nine essential amino acids.
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| lower-quality (incomplete) proteins | Dietary proteins that are low in or lack one
or more essential amino acids.
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| limiting amino acid | The essential amino
acid in lowest concentration in a food or diet
relative to body needs.
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| complementary proteins | Two food protein
sources that make up for each other’s inadequate
supply of specific essential amino acids;
together they yield a sufficient amount of all
nine and, so, provide high-quality (complete)
protein for the diet.
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| peptide bond | A chemical bond formed
between amino acids in a protein.
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| polypeptide | A group of amino acids
bonded together, from a few to 1000 or
more.
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| sickle cell disease (sickle cell anemia) | An illness that results from a malformation of
the red blood cell because of an incorrect
structure in part of its hemoglobin protein
chains. The disease can lead to episodes of
severe bone and joint pain, abdominal pain,
headache, convulsions, paralysis, and even
death.
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| denaturation | Alteration of a protein’s
three-dimensional structure, usually because
of treatment by heat, enzymes, acid or
alkaline solutions, or agitation.
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| pepsin | A protein-digesting enzyme
produced by the stomach.
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| trypsin | A protein-digesting enzyme secreted
by the pancreas to act in the small intestine.
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| protein turnover | The process of breaking
down proteins and then resynthesizing new
proteins by cells. In this way the cell will have
the proteins it needs to function at that time.
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| capillary bed | Network of one-cell thick
vessels that create a junction between arterial
and venous circulation. It is here that gas and
nutrient exchange occurs between body cells
and the blood.
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| extracellular space | The space outside cells;
represents one-third of all body fluid.
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| pool | The amount of a nutrient stored within
the body that can be mobilized when needed.
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| carbon skeleton | Amino acid structure that
remains after the amino group (—NH2) has
been removed.
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| urea | Nitrogenous waste product of protein
metabolism; major source of nitrogen in the
urine, chemically .
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| edema | The buildup of excess fluid in
extracellular spaces.
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| buffers | Compounds that cause a solution to
resist changes in acid-base conditions.
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| protein equilibrium | A state in which
protein intake is equal to related protein losses;
the person is said to be in protein balance.
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| positive protein balance | A state in which
protein intake exceeds related protein losses,
such as during times of growth.
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| negative protein balance | A state in which
protein intake is less than related protein
losses, such as often seen during acute illness.
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| vegan | A person who eats only plant foods.
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| fruitarian | A person who primarily eats
fruits, nuts, honey, and vegetable oils.
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| lactovegetarian | A person who consumes
plant products and dairy products.
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| lactoovovegetarian | A person who
consumes plant products, dairy products,
and eggs.
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| protein-calorie malnutrition (PCM) | A
condition resulting from regularly consuming
insufficient amounts of calories and protein.
The deficiency eventually results in body
wasting, primarily of lean tissue, and an
increased susceptibility to infections.
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| marasmus | A disease resulting from
consuming a grossly insufficient amount of
protein and calories; one of the diseases
classed as protein-calorie malnutrition.
Victims have little or no fat stores, little
muscle mass, and poor strength. Death from
infections is common.
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| kwashiorkor | A disease occurring primarily
in young children who have an existing
disease and consume a marginal amount of
calories and insufficient protein in relation
to needs. The child generally suffers from
infections and exhibits edema, poor growth,
weakness, and an increased susceptibility to
further illness.
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| gruels | A thin mixture of grains or legumes in
milk or water.
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| preterm | An infant born before 37 weeks of
gestation; also referred to as premature.
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