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| == '''[[Potassium in nutrition and human health]]''' == | | == '''[[Pompeii]]''' == |
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| To maintain [[Life|life]] and [[health]], the diet of humans must contain the chemical element,<b>[[potassium]]</b>, in its ionic form (K<sup>+</sup>), usually consumed as potassium salts of organic acids in food (e.g., potassium citrate), found most abundantly in non-grain plant foods (vegetables and fruits).
| | {{Image|Pompeii's forum.jpg|right|200px|"The forum at Pompeii with Mt. Vesuvius in the background."}} |
| In 2004-2006, and again in 2010, the ''Institute of Medicine of the National Academies of Science'' <ref name=ottendribook>Otten JJ, Hellwig JP, Meyers LD (editors) (2006) Dietary Reference Intakes: The Essential Guide to Nutrient Requirements. National Academies Press. Pages 370-379. ISBN 0-309-65646-X</ref> and its ''Food and Nutrition Board'' <ref name=napdri04>Panel on Dietary Reference Intakes for Electrolytes and Water. Standing Committee on the Scientific Evaluation of Dietary Reference Intakes. Food and Nutrition Board. Institute of Medicine of The National Academies (2004) [http://books.nap.edu/openbook.php?record_id=10925&page=186/ Dietary Reference Intakes For Water, Potassium, Sodium, Chloride, and Sulfate] “Potassium” pp. 186-268. The National Academies Press, Washington, D.C.</ref> <ref name=ai-k>[http://www.dietaryguidelines.gov Dietary Guidelines for Americans, 2010]. [http://www.cnpp.usda.gov/Publications/DietaryGuidelines/2010/PolicyDoc/PolicyDoc.pdf PDF (p40]. U.S Dpartment of Agriculture. U.S. Department of Health and Human Services.</ref> recommended that adult humans consume 4700 milligrams (mg) of potassium per day, or more, which, calculated from the atomic mass of potassium (39.1 mg per [[Mole (unit)|mmol)]], corresponds to 120 millimoles (mmol) potassium per day: 4700 mg/39.1 mg/mmol=120 mmol. That recommended intake of potassium substantially exceeds estimates from recent surveys of average intakes by the general population, raising the possibility that a persisting state of suboptimal body potassium content, and rate of throughput of potassium, prevails in the general population. <ref name=03-04K>[http://www.ars.usda.gov/Services/docs.htm?docid=14958 What We Eat in America, NHANES 2003-2004, Tables. 1. Nutrient Intakes: Mean Amounts Consumed per Individual, One Day, 2003-2004 (Downloadable PDF File)]</ref> <ref name=05-06K>[http://www.ars.usda.gov/SP2UserFiles/Place/12355000/pdf/0506/Table_1_NIF_05.pdf Nutrient Intakes: Mean Amounts Consumed per Individual, One Day, 2005-2006.] U.S. Department of Agriculture, Agricultural Research Services, Fast Facts, Reports/Articles, and Tables (2005-2006).</ref> <ref name=eatk2010>[http://www.ars.usda.gov/Services/docs.htm?docid=18349 What We Eat in America, 2009-2010]. USDA. Downladable pdf Tables.</ref>
| | '''Pompeii''' was a [[Ancient Rome|Roman]] settlement in [[Campania]], situated where the River Sarno drains into the [[Bay of Naples]]. When Pompeii was founded and who by is uncertain,<ref>Beard, Mary (2008) ''Pompeii: The Life of a Roman Town'', p. 34. London: Profile Books. ISBN 9781846684715.</ref> but by the mid-6th century occupied an area of 66 hectares. In the 1st century it became a Roman colony. In A.D. 79 Pompeii and nearby [[Herculaneum]] were buried when [[Mount Vesuvius]] erupted. The settlement was preserved and has become an important [[archaeology|archaeological]] site. In [[Roman mythology]], Pompeii was founded by [[Heracles|Hercules]] and may have been where the cult dedicated to the demi-god originated.<ref>Cooley, Alison & Cooley, M. G. L (2004). ''Pompeii: a sourcebook'', pp. 6–8, 17. London: Routledge. ISBN 9780415262118.</ref> |
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| Subsequent sections will discuss potassium intake recommendations for children and special groups, as well as more recent perspectives on the 'optimal' requirements for dietary potassium in humans.
| | The site of Pompeii was lost until the 18th century. Marble which had been worked on by masons was found in the area, and led to investigations which resulted in the discovery of Herculaneum. In 1748, Pompeii itself was discovered. In this first phase of rediscovery, investigations were funded by the wealthy but inflicted much damage on the site as artworks were taken away to be displayed in the patrons' homes. Pompeii and Herculanuem gained international renown in 1762 due to the writings of [[Joachim Winckelmann]], but the first rigorous archaeological excavations only began in 1860.<ref>Renfrew, Colin & Bahn, Paul (2004). Archaeology: Theories, Methods and Practice, 4th edition. Thames & Hudson. pp. 24–25. ISBN 0-500-28441-5.</ref> |
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| ===General considerations===
| | The reason Pompeii is so well known today is not because it was exceptional in its time, but because of its remarkable preservation which offers [[archaeology|archaeologists]] insight into the Roman way of life. In the words of Alison E. Cooley and M. G. L. Cooley: "Pompeii was not a particularly significant Roman town. ... No Pompeian made his mark on Roman literature or politics. No crucial moments in Rome's history hinge on Pompeii. Yet today, because of the accident of its fate, Pompeii is a Unesco world heritage site, attracting up to five hundred times as many visitors each year as actually used to live in the town."<ref>Cooley & Cooley, ''Pompeii: a sourcebook'', p. 1.</ref> |
| Potassium ranks as the most abundant cation (positive ion) inside animal [[Cell (biology)|cells]] (intracellular), and as such contributes critically in numerous important ways to the optimal functioning of cells and therefore to optimal functioning of the organ systems and individuals they compose. Among other metabolic functions, potassium plays a role in the synthesis of proteins and in the biochemical transformations required for carbohydrate metabolism.
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| Potassium plays an esential role in maintaining the electrical potential difference across the cell's plasma membrane, the intra- to extra-cellular electrical potential difference, typically referred to as the 'membrane potential'. That physicochemical regulatory function importantly enables normal transmission of information along nerves (nerve impulse transmission), normal contraction of muscle fibers, and normal functioning of the heart. The concentration of potassium inside cells (the intracellular fluid) exceeds that outside cells (the extracellular fluid) by an order of magnitude (~30 times), whereas the extracellular concentration of sodium exceeds that of its intracellular concentration by an order of magnitude (~10 times), the reverse of the situation with potassium. Those concentration differences between potassium ions and sodium ions generates the membrane potential, the inside potential negative with respect to the outside potential. A protein-based ion-pumping mechanism located within the lipid bilayer of the....
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| By influencing the electrical potential difference across the cell membrane, the ratio of the [[concentration]]s of potassium in intracellular fluid (ICF) to that in the cells' surrounding extracellular fluid (ECF) has important effects on the rate of transmission of electrical activity (pulses) along nerve fibers and skeletal muscle cells, which, among other things, affects the degree of contraction of the smooth muscles of arteries and arterioles (vascular tone).<ref name=moczydlowski2009>Moczydlowski EG. (2009) Electrophysiology of the Cell Membrane. In: Boron WF, Boulpaep EL (editors), Medical Physiology, 2nd ed. Saunders/Elsevier: Philadelphia. ISBN 9781416031154.</ref> Inasmuch as extracellular potassium varies in the 3-6 mmol/L range, while intracellular potassium concentrations average about 145 mmol/L, small changes in extracellular potassium concentration have a greater effect on the ICF-to-ECF potassium concentration ratio than similar small changes in intracellular potassium concentration. Subsequent sections discuss the implication of changes in the ICF-to-ECF potassium concentration ratio in human physiology.
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(PD) Photo: Central Intelligence Agency "The forum at Pompeii with Mt. Vesuvius in the background."
Pompeii was a Roman settlement in Campania, situated where the River Sarno drains into the Bay of Naples. When Pompeii was founded and who by is uncertain,[1] but by the mid-6th century occupied an area of 66 hectares. In the 1st century it became a Roman colony. In A.D. 79 Pompeii and nearby Herculaneum were buried when Mount Vesuvius erupted. The settlement was preserved and has become an important archaeological site. In Roman mythology, Pompeii was founded by Hercules and may have been where the cult dedicated to the demi-god originated.[2]
The site of Pompeii was lost until the 18th century. Marble which had been worked on by masons was found in the area, and led to investigations which resulted in the discovery of Herculaneum. In 1748, Pompeii itself was discovered. In this first phase of rediscovery, investigations were funded by the wealthy but inflicted much damage on the site as artworks were taken away to be displayed in the patrons' homes. Pompeii and Herculanuem gained international renown in 1762 due to the writings of Joachim Winckelmann, but the first rigorous archaeological excavations only began in 1860.[3]
The reason Pompeii is so well known today is not because it was exceptional in its time, but because of its remarkable preservation which offers archaeologists insight into the Roman way of life. In the words of Alison E. Cooley and M. G. L. Cooley: "Pompeii was not a particularly significant Roman town. ... No Pompeian made his mark on Roman literature or politics. No crucial moments in Rome's history hinge on Pompeii. Yet today, because of the accident of its fate, Pompeii is a Unesco world heritage site, attracting up to five hundred times as many visitors each year as actually used to live in the town."[4]
.... (read more)
| notes
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- ↑ Beard, Mary (2008) Pompeii: The Life of a Roman Town, p. 34. London: Profile Books. ISBN 9781846684715.
- ↑ Cooley, Alison & Cooley, M. G. L (2004). Pompeii: a sourcebook, pp. 6–8, 17. London: Routledge. ISBN 9780415262118.
- ↑ Renfrew, Colin & Bahn, Paul (2004). Archaeology: Theories, Methods and Practice, 4th edition. Thames & Hudson. pp. 24–25. ISBN 0-500-28441-5.
- ↑ Cooley & Cooley, Pompeii: a sourcebook, p. 1.
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