Potassium - Mineral
There are estimated to be approximately
250 grams of potassium present in the adult human body. Most of the potassium
in the body is intercellular and, reciprocally most of the bodys sodium
The movement of potassium into extracellular fluid from
muscle cells is an important part of the contraction mechanism of muscle
Potassium is pumped into the cell by active transport
systems, which concomitantly pump sodium out of the cell. The preferential
segregation of sodium and potassium across the cells biological membrane
is important in maintaining osmotic balance, the electrochemical gradient of
membranes, and the regulation of extracellular fluid volume. This mechanism of
ion pumping is also instrumental in the restoration of potassium/sodium
gradient after the ionic transmission of nerve impulses.
Potassium is important in preserving the acid/base
balance of the body, and is an elemental constituent of blood
Potassium is principally found within
cellular fluids and its counterpart, sodium, is mostly found within the
extracellular fluids. The segregation of these two ions occurs by means of an
adenosine triphosphate (ATP) driven "pump." The pump consists of two proteins
within the cellular membrane which, upon energy release from ATP, transport
three sodium molecules to the outside of the cell membrane, while
simultaneously bringing in two potassium molecules.
A similar pumping mechanism is used in the transport of
glucose from the intestine into the bloodstream. High sodium concentrations in
the intestinal fluids tend to promote the movement of sodium across the mucosal
cells of the intestine. As sodium is moved across the cells, glucose is
concomitantly moved into the cells. The concentration of glucose within the
cells builds up until it begins to diffuse into the bloodstream. The "pump"
mechanism pumps the sodium into the blood in exchange for potassium, thereby
eliminating sodium buildup within the cell. A similar mechanism is used to
transport amino acids.
Potassium is an essential constituent of several blood
buffer systems. Potassium complexes ionically with the sulfate group of
sulfuric acid, thereby reducing the acidity of the system by forming a
potassium sulfate salt. Potassium has a similar action in base buffer systems
with the conversion of the strong base potassium hydroxide into the relatively
neutral water molecule.
After the transmission of a nerve impulse, during which
sodium ions are shifted across the nerves synaptic membrane, potassium
and sodium are exchanged by the previously mentioned "pump" mechanism (so as to
restore the original sodium concentration on the external side of the
membrane). This "pumping" of sodium outside is essential to prepare for
subsequent nerve transmission.
Potassium acts to relax muscle contraction in opposition
to calcium, which induces contraction.
Potassium is absorbed readily in the small intestine;
excess potassium is excreted through the urine. Aldosterone hormone tends to
promote potassium excretion in substitution for sodium absorption. This is done
by activation of the renal "pump" proteins, which simultaneously exchange
potassium for sodium across the biological membrane.
Potassium absorption is hindered by the anti-inflammatory
agents colchicine and salicylazosulfapyridine; laxatives such as
phenolphthalein, cascara sagrada, and bisacodyl; and various antimicrobial
agents (e.g., tetracycline, and neomycin).
Potassium has been proven to be essential,
along with increased protein intake, in the treatment of kwashiorkor.
Potassium supplementation is effective in treatment of
potassium deficiency symptoms, which include overall muscle weakness, abdominal
bloating, heart abnormalities, as well as weak respiration.
Potassium is recommended for patients with congestive
heart failure who muse use diuretics regularly; diuretics tend to deplete
potassium levels in the body.
Potassium supplements may be used to replenish potassium
lost during periods of chronic illness, and in some patients, the potassium
lost due to stress.
Potassium is also useful in the treatment of acute
diarrhea, diabetic coma, congenital renal alkalosis, aldosteronism, and in the
case of surgical patients, to replace lost body potassium.
Potassium deficiency rarely occurs as a
result of inadequate dietary intake, but rather as a result of excessive
diarrhea or vomiting, malnutrition, surgery, or use of diuretics. On
occasion, prolonged disease may promote a decrease in potassium levels in the
Symptoms of potassium deficiencies
include overall muscle weakness, abdominal bloating, weak respiration, and
heart abnormalities (possibly heart attack).
Magnesium deficiency can also induce a
concomitant potassium deficiency.
Loss of large amounts of potassium can
lead to the condition of metabolic alkalosis (elevated blood pH) and prolonged
deficiency can enhance the prevalence of high blood cholesterol
Excesses of ionized potassium can
accumulate and become toxic in instances of a renal failure to clear excess
potassium, rapid intravenous administration, or excess ingestion of potassium
chloride (25 grams daily). Symptoms may include diarrhea, weakening of
respiration and heart action, and numbness in extremities.
Renal abnormalities can result in a
dangerous accumulation of potassium if urinary excretion is not sufficient.
This can result in hyperkalemia (elevated serum potassium levels) and possibly
provoke cardiac arrest, although this phenomenon is extremely rare.
The range of actual intake for children is
780 to 1,600 milligrams per day; adults the range is estimated at 1,950 to
5,900 milligrams per day. There is no set RDA for potassium for adults.
RDA for child/adolescent: 90 mg
RDA for infants: 90 mg
| Beef liver
|| Beet greens
| Brazil nuts
| Chicken liver
|| Hot cocoa
|| Green peas
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|| Swiss chard
| Turkey liver
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