718
UNIT FIVE
PRACTICE
55
Which are the most abundant minerals in the body?
56
What are the functions of calcium?
57
What are the functions of phosphorus?
58
Which foods are good sources of calcium and phosphorus?
3.
Potassium.
Potassium (K) is widely distributed
throughout the body and is concentrated inside cells rather
than in extracellular fl uids. On the other hand, sodium,
which has similar chemical properties, is concentrated
nucleic acids, many proteins, some enzymes, and
some vitamins. It is also in the phospholipids of cell
membranes, in the energy-carrying molecule ATP,
and in the phosphates of body fl
uids that regulate pH.
(Review the molecular structure of ATP in F
g. 4.7.)
The recommended daily adult intake of phosphorus
is 800 mg, and because this mineral is abundant in
protein foods, diets adequate in proteins are also adequate
in phosphorus. Phosphorus-rich foods include meats,
cheese, nuts, whole-grain cereals, milk, and legumes.
TABLE
18.9
|
Water-Soluble Vitamins
Vitamin
Characteristics
Functions
Sources and
RDA
*
for Adults
Conditions Associated with
Excesses
De±
ciencies
Thiamine
(Vitamin B
1
)
Destroyed by heat and oxygen,
especially in alkaline environment
Part of coenzyme required for
oxidation of carbohydrates; coenzyme
required for ribose synthesis
Lean meats, liver, eggs,
whole-grain cereals, leafy
green vegetables, legumes
1.5 mg
Uncommon,
vasodilation,
cardiac
dysrhythmias
Beriberi,
muscular
weakness,
enlarged heart
Ribof
avin
(Vitamin B
2
)
Stable to heat, acids, and oxidation;
destroyed by bases and ultraviolet light
Part of enzymes and coenzymes,
such as FAD, required for oxidation of
glucose and fatty acids and for cellular
growth
Meats, dairy products,
leafy green vegetables,
whole-grain cereals
1.7 mg
None known
Dermatitis,
blurred vision
Niacin
(Nicotinic acid,
Vitamin B
3
)
Stable to heat, acids, and bases;
converted to niacinamide by cells;
synthesized from tryptophan
Part of coenzymes NAD and NADP
required for oxidation of glucose and
synthesis of proteins, fats, and nucleic
acids
Liver, lean meats, peanuts,
legumes
20 mg
Flushing,
vasodilation,
wheezing,
liver
problems
Pellagra,
photosensitive
dermatitis,
diarrhea, mental
disorders
Pantothenic
acid
(Vitamin B
5
)
Destroyed by heat, acids, and bases
Part of coenzyme A required for
oxidation of carbohydrates and fats
Meats, whole-grain
cereals, legumes, milk,
fruits, vegetables
10 mg
None known
Rare, loss of
appetite, mental
depression,
muscle spasms
Vitamin B
6
Group of three compounds; stable to
heat and acids; destroyed by oxidation,
bases, and ultraviolet light
Coenzyme required for synthesis of
proteins and various amino acids, for
conversion of tryptophan to niacin,
for production of antibodies, and for
nucleic acid synthesis
Liver, meats, bananas,
avocados, beans, peanuts,
whole-grain cereals, egg
yolk
2 mg
Numbness,
clumsiness,
paralysis
Rare,
convulsions,
vomiting,
seborrhea
lesions
Cyanoco-
balamin
(Vitamin B
12
)
Complex, cobalt-containing
compound; stable to heat; inactivated
by light, strong acids, and strong bases;
absorption regulated by intrinsic factor
from gastric glands; stored in liver
Part of coenzyme required for synthesis
of nucleic acids and for metabolism
of carbohydrates; plays role in myelin
synthesis; required for normal red
blood cell production
Liver, meats, milk, cheese,
eggs
3–6 µg
None known
Pernicious
anemia
Folacin
(Folic acid)
Occurs in several forms; destroyed by
oxidation in acid environment or by
heat in alkaline environment; stored in
liver where it is converted into folinic
acid
Coenzyme required for metabolism
of certain amino acids and for DNA
synthesis; promotes production of
normal red blood cells
Liver, leafy green
vegetables, whole-grain
cereals, legumes
0.4 mg
None known
Megaloblastic
anemia
Biotin
Stable to heat, acids, and light;
destroyed by oxidation and bases
Coenzyme required for metabolism
of amino acids and fatty acids and for
nucleic acid synthesis
Liver, egg yolk, nuts,
legumes, mushrooms
0.3 mg
None known
Rare, elevated
blood
cholesterol,
nausea, fatigue,
anorexia
Ascorbic acid
(Vitamin C)
Chemically similar to monosaccharides;
stable in acids but destroyed by
oxidation, heat, light, and bases
Required for collagen production,
conversion of folacin to folinic acid,
and metabolism of certain amino
acids; promotes absorption of iron and
synthesis of hormones from cholesterol
Citrus fruits, tomatoes,
potatoes, leafy green
vegetables
60 mg
Exacerbates
gout and
kidney stone
formation
Scurvy, lowered
resistance
to infection,
wounds heal
slowly
*
RDA = recommended daily allowance.
previous page 748 David Shier Hole's Human Anatomy and Physiology 2010 read online next page 750 David Shier Hole's Human Anatomy and Physiology 2010 read online Home Toggle text on/off