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Nutrients Involved in Fluid and Electrolyte Balance

9. Nutrients Involved in Fluid and Electrolyte Balance. Body Fluids. Body fluid is the liquid portion of cells and tissues Characterized by its ability to move freely and changeably, adapting to the shape of the container that holds it About 50−70% of healthy adult body weight. Body Fluids.

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Nutrients Involved in Fluid and Electrolyte Balance

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  1. 9 Nutrients Involved in Fluid and Electrolyte Balance

  2. Body Fluids • Body fluid is the liquid portion of cells and tissues • Characterized by its ability to move freely and changeably, adapting to the shape of the container that holds it • About 50−70% of healthy adult body weight

  3. Body Fluids • Intracelluar fluid: within the cell • 2/3 of body fluid • Extracellular fluid: outside the cell • 1/3 of body fluid • Interstitial fluid flows between cells that make up a particular tissue or organ (muscle, liver) • Intravascular fluid is the water in the blood and lymph • Plasma transports blood cells within arteries, veins, and capillaries Intracellular and Extracellular Fluid

  4. Body Fluids • Fluid composition of tissue varies by: • Tissue type: lean tissues have higher fluid content than fat tissues • Gender: males have more lean tissue and therefore more body fluid than females • Age: decrease in body water results partly from loss of lean tissue as people age

  5. Electrolytes • Dissolved substances that disassociate in solution into electrically charged particles called ions • Positive charge: sodium, potassium • Negative charge: chloride, phosphorus • Predominant electrolytes • Extracellular fluid: potassium, phosphorus • Intracellular fluid: sodium, chloride Role of Electrolytes in Water Balance

  6. Functions of Body Fluids • Fluids dissolve and transport substances • Water is an excellent solvent because it dissolves a variety of substances • Water-soluble substances are readily transported in the bloodstream: amino acids, glucose, vitamins, minerals, medications • Fatty substances must be attached to or surrounded by water-soluble proteins

  7. Functions of Body Fluids • Fluids account for blood volume • Appropriate body fluid levels are essential for maintaining healthful blood volume • Blood pressure increases when blood volume rises • High blood pressure (hypertension) is a risk factor for heart disease and stroke • Low blood pressure can cause people to feel tired, confused, or dizzy • Kidneys help to regulate blood volume and blood pressure

  8. Functions of Body Fluids • Fluids account for blood volume • Antidiuretic hormone (ADH) stimulates the kidneys to reabsorb water, reducing urine • Renin responds to decreased blood pressure • Angiotensin II (vasoconstrictor) increases blood pressure • Aldosterone signals the kidneys to retain sodium and chloride, thereby retaining water, increasing blood pressure, and decreasing urine output

  9. Functions of Body Fluids • Fluids help maintain body temperature • Body temperature must be within a safe range • Water has a high capacity for heat, which means that only sustained high heat can increase body temperature • Sweating releases heat as the evaporation of water from the skin cools the skin and blood

  10. Functions of Body Fluids • Protect and lubricate tissues • Cerebrospinal fluid protects the brain and spinal cord • Amniotic fluid protects the fetus • Synovial fluid lubricates joints • Tears cleanse and lubricate eyes • Saliva moistens food for swallowing

  11. Functions of Electrolytes • Electrolytes help regulate fluid balance • Cell membranes are permeable to water, but not freely permeable to electrolytes • Water moves by osmosis to areas where the concentration of solute is high • This action provides a means to control movement of water into and out of the cells • Osmotic pressure keeps electrolytes in solution from drawing liquid toward them across a semipermeable membrane

  12. Functions of Electrolytes • Electrolytes enable nerves to respond to stimuli • Nerve impulses are initiated at nerve cell membranes in response to a change in electrical charge across the membrane • Depolarization—Action Potential—Repolarization • Sodium and potassium ensure that nerve impulses are generated, transmitted, and completed

  13. Functions of Electrolytes • Electrolytes signal muscles to contract • Muscles are stimulated to contract in response to stimulation of nerve cells • Influx of calcium into the muscle from the extracellular space stimulates contraction • Muscles can relax after contraction once the electrical signal is complete and calcium is pumped out of the muscle cell

  14. Fluid Balance • Thirst mechanism (hypothalamus) prompts us to drink when it is stimulated by • Increased concentration of salt and other dissolved substances in the blood • A reduction in blood volume and blood pressure, such as during profuse sweating, vomiting, diarrhea, or low fluid intake • Dry mouth and throat from reduced saliva • ADH signals the kidneys to retain water

  15. Fluid Balance • Body gains fluids • Water enters the body through beverages • Some foods have very high water content • Water from metabolic reactions contributes 10−14% of daily water need

  16. Fluid Balance • Sensible water loss • Kidneys excrete water as urine • Sweat during exercise or in hot environment • Insensible water loss • Skin (not sweating) or lungs during exhalation • Significant loss • Illness, injury, exercise, high altitude, pregnancy, breastfeeding, diuretics

  17. Water • Water • Essential for life • Amount needed varies with gender, age, body size, health status, physical activity level, environment • Sources of drinking water: carbonated, mineral, distilled, purified, tap, bottled ABC Video Bottled Water

  18. Water • What happens if we drink too much water? • Becoming overhydrated is rare • Dilution of blood sodium concentration • What happens if we don’t drink enough water? • Dehydration • Leading cause of death around the world Water Balance

  19. Sodium • Sodium • Major positively charged electrolyte in the extracellular fluid • Blood pressure and acid−base balance • Nerve impulse transmission • Muscle contraction and relaxation • Assists in glucose absorption from the small intestine

  20. Sodium • Sodium • AI: 1,500 mg, most recommend < 2,300 mg/day • Processed foods are high in sodium • High blood pressure more common from high-sodium diets • Excessive intake may increase urinary calcium excretion in some people, which in turn may increase the risk for bone loss

  21. Sodium • What if you consume too much sodium? • Hypernatremia is an abnormally high blood sodium concentration • Patients with congestive heart failure or kidney disease cannot effectively excrete sodium • Causes high blood volume, edema (swelling), and high blood pressure

  22. Sodium • What if you don’t consume enough sodium? • Hyponatremia is an abnormally low blood sodium level • From prolonged sweating, vomiting, diarrhea • Symptoms: headaches, dizziness, fatigue, nausea, vomiting, and muscle cramps • If untreated: seizures, coma, and death

  23. Potassium • Potassium • Major positively charged electrolyte in the intracellular fluid • Together with sodium, maintains fluid balance and regulates the contraction of muscles and transmission of nerve impulses • High potassium intake helps maintain a lower blood pressure

  24. Potassium • Recommended intake • 4,700 mg/day • Sources of potassium • Good sources: fresh fruits, vegetables, legumes, and whole grains • Processing foods increases sodium and decreases potassium content

  25. Potassium • What happens if you consume too much potassium? • Hyperkalemia: high blood potassium levels • Can alter normal heart rhythm, resulting in heart attack and death • People with kidney disease are unable to regulate their blood potassium levels and should avoid consuming potassium-containing salt substitutes

  26. Potassium • What happens if you don’t consume enough potassium? • Hypokalemia: low blood potassium levels • Seen in people with kidney disease or diabetic ketoacidosis • Can occur when taking certain diuretics and with extreme dehydration, vomiting, diarrhea, alcohol abuse, long-term consumption of natural licorice (glycyrrhizic acid or GZA), or eating disorder (abnormal heart rhythms)

  27. Chloride • Functions of chloride • In extracellular fluid • Aids digestion: hydrochloric acid (HCl) in the stomach • Assists the immune system and in the transmission of nerve impulses • Recommended intake • AI: 2,300 mg/day

  28. Chloride • What happens if you consume too much chloride? • Primary dietary source: table salt • Hypertension in salt-sensitive individuals • What happens if you don’t consume enough chloride? • This is rare but can occur in people with severe dehydration, frequent vomiting, and eating disorders

  29. Phosphorus • Functions of phosphorus: • Major intracellular negatively charged electrolyte • Required for fluid balance • Critical role in bone formation • Regulates biochemical reactions by activating or deactivating enzymes (phosphorylation) • Found in ATP, DNA, RNA, cell membranes (phospholipids), and lipoproteins

  30. Phosphorus • Recommended intake • RDA for phosphorus is 700 mg/day • Sources of phosphorus • Widespread in many foods • High in protein foods (meat, milk, eggs) • More readily absorbed from animal sources • Phytic acid: plant storage form • Soft drinks

  31. Phosphorus • What happens if you consume too much phosphorus? • High blood phosphorus can occur among people with kidney disease or when taking too many vitamin D supplements • Causes muscle spasms, convulsions • What if you don’t consume enough phosphorus? • Deficiencies of phosphorus are rare

  32. Medical Disorders • Disorders related to fluid and electrolyte imbalance include: • Dehydration • Heatstroke • Water intoxication • Hypertension • Neuromuscular disorders • Obesity

  33. Dehydration • Dehydration occurs when fluid loss exceeds fluid intake • Commonly due to heavy exercise or high environmental temperatures • Elderly and infants are at increased risk

  34. Heatstroke • Heatstroke occurs from failure in the body’s heat-regulating mechanisms • Hot, humid environments • Symptoms: rapid pulse, hot and dry skin, high body temperature, loss of consciousness • Fatal during exercise in extreme heat • Stop exercising when feeling dizzy, light-headed, disoriented, or nauseated

  35. Water Intoxication • Overhydration can occur but it is rare • Kidneys retain too much water, causing overhydration and hyponatremia • Documented cases of deaths among college students (hazing rituals)

  36. Hypertension • Hypertension: major chronic disease characterized by high blood pressure • Often without symptoms • Increases a person’s risk of heart disease, stroke, kidney disease • Can reduce brain function, impair physical mobility, and cause death • Systolic pressure over 140 mm Hg • Diastolic pressure over 90 mm Hg

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