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Potassium

Potassium. +. K. K +. Atomic Number: 19. Electron Configuration: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1. Never found Free in Nature. Reacts Violently with Water and Air. KCl used as table salt substitute and to stop the Heart (lethal injection).

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Potassium

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  1. Potassium + K

  2. K+ Atomic Number: 19 Electron Configuration: 1s2 2s2 2p6 3s2 3p6 4s1 Never found Free in Nature Reacts Violently with Water and Air KCl used as table salt substitute and to stop the Heart (lethal injection) Used in Fertilizer and Gun Powder and Glass manufacturing

  3. K+ History • 1807- Sir Humphry Davy discoveres K • 1871- Salkowski first describes K absorption & excretion • 1874- Ringer shows that ions balance in natural salts • 1894- Von Bunge describes relationships between Na & K • 1926- Miller shows that dietary K is essential for normal life & Growth • 1966- Woodbury postulates existence of electrogenic Na-K pump in cell membranes

  4. K+ General Functions • Principle intracellular ion • Intracellular Fluid Regulation: • Osmotically active, involved in buffering, viscosity, CO2 transport (RBC), & Solublization of proteins present in the cell • Membrane Effects: • Influences membrane permeability, sodium pump action, muscular contraction & nerve impulse conduction

  5. K+ Facts • Present in all plants and animals • Alkali metal • Atomic Wt: 39.1 • Present in the body as K+ • Common inorganic anions: • Cl, HPO4, bicarbonate, tartate, citrate • Organic anion: • Gluconate • Body Content: 136g/70kg (3000-4000mmol) • Relative Organ Concentrations: • RBC > muscle > brain > intestine > heart > pancreas > liver > kidney > lungs > uterus > skin > adrenal > skeleton > serum

  6. K+ Facts • Skeletal Muscle’s mass and K+ concentration makes total body K+ track closely to lean body mass • ~2% total body K+ outside of cells, 98% intracellular • Intracellular concentration = 140 mmol/L • Extracellular concentration narrowly maintained @ 3.5-5.5 mmol/L • Important Equation: E= -61.5 log ([K]ICF/[K]ECF) E= membrane potential difference in millivolts

  7. K+ Facts • Important for electrical properties of membranes • Hyper or hypo Kalemia can = failure to depolarize properly • Symptoms of Deficiency & Excess are similar • Weakness, lethargy, gastric hypomotility, cardiac arrhythmias

  8. K+ Sources • Food Group K+ mg/100 kcal, Examples Leafy Greens 1,300, Spinach, lettuce, cabbage, kale Fruit of vines 1,200, Tomato, cukes, zucchini, eggplant, pumpkin Root Veggies 975, Carrots, radishes, turnip, rutabaga, onion Beans & peas 500, Kidney, green & soy beans; green & chick peas Tree fruits 430, Apple,orange,banana,apricot, grapes, strawberries Tubers 400, Potatoes, sweet potatoes, yams Milk & yogurt 350, Skim & whole milk or yogurts Meats 230, Beef, lamb, pork, poultry, fish, rabbit Nuts 110, Walnut, cashew, almonds, brazil, fibert Eggs & Cereal 90, All poultry eggs, wheat, rice, oats, rye Cheese & pecans 50, Edam, stilton, cheddar, pecans

  9. K+ Influences on Availability • Decreased: - Boiling food in water w/ no added salt, addition of excess NaCl, meat diets, high processed food diets, diarrhea • Increased: • Vegetarian diets, use of salt substitutes • Typical US diets provide 50-80 mmol K+ per day • Balance of intake/excretion less percise than Na & Cl • Like Na, tolerance to high intakes w/ gradual increase

  10. K+ Absorption & Excretion • Absorption • K+ well absorbed, >90% • Absorbed across entire intestinal tract • Active transport & passive diffusion and/or facilitation • Absorption enhanced by Na+, Mg2+, ionophore • Antagonized by Ca2+, cardiac glycosides & aldosterone (reverse secretion into gut) • Extracellular Transport • Free in Blood as K+

  11. K+ Absorption & Excretion • Excretion • Half life in blood: ~0.39% of Plasma K+ excreted per minute at normal plasma levels (1.72 mg/100ml) • Freely filtered in glomerulus, reabsorbed in proximal tubules, & secreted in distal tubule via a process facilitated by aldosterone • Intestine & bile have little effect on body K+ content in healthy subjects: 5-10% daily excretion • Hormones • Insulin directly stimulates K+ uptake by muscle and liver • Aldosterone increases renal excretion • Catecholamines: beta, hypo K+; alpha, hyper K+

  12. K+ Symptoms • Deficiency • Muscle weakness, cardiac arrhythmia, paralysis, bone fragility, sterility, adrenal hypertrophy, poor growth, weight loss, death • Toxicity • Acute: tonoclonic convulsions, CNS paralysis, asphyxial convulsions, diarrhea, gastroenteritis, polydipsia, diuresis, dehydration, renal necrosis, fever, prostration, dilation of the heart, cardiac arrhythmia, lung collapse, respiratory failure • Chronic: cardiac & CNS depression, mental confusion, weakness, vomiting, numbness, tingling, flaccid paralysis of extremities

  13. K+ Cellular Transport • Active Transport = Compartmentalization of K+ • Na, K – ATPase pump • H,K – ATPase pump • Na-2Cl-K CoTransporters • K conductance channels • Insulin • Works to prevent hyperkalemia • Catecholamines • Blunt increases in plasma K due to heavy exercise

  14. K+ Deficiency Causes • Reduced K intake • Deficient diet or inadequate absorption • Renal Losses • Diuretics • Osmotic diuresis (diabetes) • Excess mineral corticorticoid • Intestinal Losses • Diarrhea • Laxative abuse • Redistribution • Excess Catacholamines or insulin • Abnormal skeletal muscle calcium channels

  15. K+ Excess Causes • Excessive Intake • Decreased renal loss • Acute renal failure or end stage renal disease • Mineralcorticoid deficiency • Potassium-sparing diuretics • Redistribution • Hemolysis, cellular necrosis, muscle injury • Catecholamine antagonists • Insulin deficiency • Abnormal skeletal muscle calcium channels

  16. K+ Hypertension • Increased K+ diets are hypotensive • Mechanisms not fully defined • Evidence based on epidemiology in nature • Rancho Bernado cohort = 40% ↓ in mortality after 12 yrs w/ ↑ F&V intake • DASH provided first intervention data • Whole food so no one nutrient could be tested in isolation • Complex effect: K+, Mg++, Ca++, & Citrate found in fruits that is converted to acid buffering bicarbonate in the body • Blood Pressure appears to be the result of complex multi-nutrient interactions • Some effects observed acutely, others are chronic

  17. K+ Bones • K+ now strongly implicated in bone health • Counteracts Na effects to increase Ca excretion • Typically consumed as citrate fruits that buffer acid load • Atkins diet = acidotic & calciuric • Increased kidney stone formation • Marginal K+ Deficiency • No overt symptoms of hypokalemia • Insulin resistance occurs

  18. Hi Meat Lo Fruit & Vegetable ↑Sodium ↑Chloride ↓Potassium ↓HCO3+ ↑ H+ ↓ Renal Acidification Low grade Meta- bolic acidosis ↑Fluid Vaso- constriction ↓HCO3+ ↑ H+ ↑Urinary Ca++ ↓ Renal Na Excretion (gene/age) ↓Urinary Citrate ↑Kidney Stones ↑Central Blood Volume ↑Bone base titration ↑Osteoclastic activation ↓Osteoblastic activation Essential Hypertension Osteoporosis

  19. K+ Recommended Intake • DRI’s Published February 2004

  20. K+ Fun Facts • Lethal Injection Dosage: 100mEq KCl • Insulin/K+ uptake – • Insulin binds to recepter = hyperpolarization of cell membrane = K+ uptake • Insulin also stimulates Na+ K+ Pump = cellular uptake of K+ • Hyperkalemia Treatment: • Chronic – Kayexalate (binding resin), Binds K+ in large intestine, 2-12 hrs • Acute – treat with insulin, glucose, and Bicarb. = cellular K+ uptake

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