Module 8 - Water And Electrolytes-1 PDF

03/01/20 21 WATER AND ELECTROLYTES Learning Objectives 1. Describe how elements in a water molecule allow other particles to dissolve in water. 2. List body compartments in which water is found and describe water distr...

03/01/20 21 WATER AND ELECTROLYTES Learning Objectives 1. Describe how elements in a water molecule allow other particles to dissolve in water. 2. List body compartments in which water is found and describe water distribution in the compartments. 3. List sources of water intake and loss. 4. Describe how water intake and retention is regulated in the body. 5. Identify risk factors for developing hyponatremia and dehydration. 1  03/01/20 21 Learning Objectives 6. List the functions of water and electrolytes in the body. 7. List food sources of sodium and potassium. 8. Identify Adequate Intake values for sodium, potassium and water in adults. 9. Identify the organ responsible for water and waste elimination in the body. 10.Discuss how the proposed updates to the food label may help improve sodium and potassium intake. Learning Objectives 11.Identify the systolic and diastolic blood pressures that correspond with a diagnosis of hypertension. 12.List the minerals that may influence blood pressure. 13.Describe the DASH diet, including the list of minerals that the diet is a good source of and the food groups these minerals are found in. 14.List other diet/lifestyle changes recommended to improve blood pressure and prevent or treat hypertension. 2  03/01/20 21 Water and Water Balance ⮚ Water consists of 2 hydrogen atoms and 1 oxygen atom bonded together oBonding causes a shift in charge among individual atoms ♦Hydrogen side: slightly + ♦Oxygen side: slightly – ♦Allows water to attract other water molecules ♦Other substances that are also charged can dissolve in it Water and Water Balance ⮚ Within the body, water is found in two major compartments: oIntracellular ◆~60% of body water oExtracellular ◆~40% of body water ♦Includes: Interstitial fluid Intravascular fluid 3  03/01/20 21 Water Balance: Water Intake vs. Water Loss Intake Losses ⮚ Beverages ⮚ Urine ⮚ Foods ⮚ Feces ⮚ Metabolic water ⮚ Insensible losses oFrom breakdown of oSweating carbohydrates, fats, and proteins oAir expiration o1 to 1 ½ cups per day 4  03/01/20 21 Water balance ⮚ Water fluctuations in body are common ⮚ Body has no water storage mechanism oLosses must be replaced from consumption of water oWater is essential ♦Consumption required every day ⮚ Critical function of water in body: oBody temperature regulation ♦Water absorbs body heat ♦ Heat released at skin via sweat 5  03/01/20 21 Hydration: Water Intake and Retention ⮚ Hypothalamus in brain controls body’s perceived need for water: oThirst ♦Triggered when: Water levels in blood and solute concentration Perception of thirst lags behind time when body first needs water ⮚ Two hormones help maintain hydration 1. Antidiuretic hormone oReleased by pituitary gland to signal kidneys to retain water 2. Aldosterone oProduced by adrenal glands above kidneys oInduces kidneys to retain sodium and water Hydration: Water Intake ⮚ Recommendation for adults o1–1.5 mL/kcal of energy expenditure ♦ foods and beverages combined oRequirements vary based on disease state and activity level ⮚ Excess water consumption oWater intoxication ♦Dilution of blood electrolytes, particularly sodium oAlso known as hyponatremia 6  03/01/20 21 The Dangers of Dehydration ⮚ Dehydration can occur from: oExcessive water loss via sweat oVomiting and diarrhea ⮚ Body’s function is altered at all levels of dehydration oMild: Thirst, some lack of mental clarity and mild fatigue oModerate: Reduced athletic ability oSevere: Cramping and heat exhaustion oIf water loss continues, hallucinations and heatstroke occur. 7  03/01/20 21 The Role of Kidneys and Urine in Water Balance ⮚ Urine is primary path for: oWater loss and excretion of metabolic waste oRegulation of extracellular fluid composition ⮚ Kidney controls urine and blood composition. oNephron ♦Microscopic structures that filter blood ♦ 1 million in each kidney ⮚ Composition of urine: oWater and electrolytes oUrea and creatinine Figure 8.3: Nephron of the Kidney 8  03/01/20 21 Electrolytes: Sodium, Potassium, and Chloride ⮚ Electrolytes oMinerals that, when placed in water, become charged particles ⮚ Cations: minerals with a positive charge ⮚ Anions: minerals with a negative charge ⮚ Na+, K+ and Cl- are electrolytes important for water balance: o Sodium (Na+): primary cation in extracellular fluid o Potassium (K+) : primary intracellular cation o Chloride (Cl-) : an anion, more concentrated in extracellular fluid 9  03/01/20 21 Dietary Sodium ⮚ Health professionals universally advise moderating salt intake. ⮚ Is the primary source of salt in our diet the salt we add to food? oMain dietary source of sodium is processed foods oAdded to foods for taste and/or as a preservative oVery little from naturally occurring sodium 1  03/01/20 21 Dietary Sodium and Chloride ⮚ AI for Sodium: o1500 milligrams (mg) per day for adults up to age 50 o1200 mg per day for those over age 70 ⮚ UL for Sodium: o2300 mg for adults ⮚ Natural chloride content of most foods is low ⮚ Sodium chloride, or table salt, is approximately 60% chloride 1  03/01/20 21 Dietary Potassium ⮚ The AI for potassium is 4700 mg per day oMost Americans eat less than AI ⮚ Rich sources of potassium: oFresh fruits and vegetables oLegumes oMilk oMeats oWhole grains oOther sources: salt substitutes (KCL) 1  03/01/20 21 Functions of electrolytes 1.Water and electrolyte balance: ⮚ Water and electrolytes are moved across cell walls through two processes: oMovement from area of greater concentration to area of lesser concentration: ♦Diffusion oMovement of water across membrane from area with fewer particles where to area with more particles ♦Osmosis 2.Acid–base balance (pH) ⮚ Maintenance of normal blood pH Functions of electrolytes: osmosis 1  03/01/20 21 Functions of electrolytes 3. Nerve transmission ⮚ Sodium and potassium have charges when dissolved in water ⮚ Assist in function of excitable cells in nerves oSodium moves into the cell and potassium moves out 4. Gastric pH ⮚ Hydrochloric acid contains chloride oProtein digestion oAbsorption of some minerals 1  03/01/20 21 Deficiencies ⮚ Sodium Deficiencies oRarely occur oSodium loss accompanied by loss of body water ♦shock-like symptoms ◆blood volume and veins collapse oWater intoxication ♦Can result in condition associated with low sodium in blood Hyponatremia Hypertension ⮚ 2 components of blood pressure (BP) readings 1. Systolic blood pressure o Peak pressure generated when the heart contracts and forces blood to move 2. Diastolic blood pressure o Lowest blood pressure reading during cardiac relaxation 1  03/01/20 21 Blood Pressure and Hypertension Diagnosis of hypertension associated with elevation of BP. Systolic BP Diastolic BP (mm Hg) (mm Hg) Normal < 120 and < 80 *Prehypertension 120 – 129 and < 80 *Hypertension 130 – 139 or 80-89 Stage 1 *Hypertension ≥ 140 or ≥90 Stage 2 *These values correspond to the most recently updated blood pressure guidelines in 2017/2018. Hypertension ⮚ Roughly 25% of Americans had high blood pressure based on previous definition; 54% of adults have high bp under 2017/2018 definitions. o risk for for coronary heart disease and stroke oMay also lead to kidney damage ⮚85% of hypertension cases due to unknown cause oHigh blood pressure due to unknown cause is: ♦Essential hypertension ⮚Most hypertension is treatable with diet and exercise modifications and/or medication 1  03/01/20 21 Dietary changes for blood pressure control ⮚ Sodium: oHigh amounts may increase risk of hypertension in some people oRequired on food labels ⮚ Potassium: oAppears to relax blood vessels, which BP oRecommendation to increase potassium intake ⮚ Other minerals: oCalcium oMagnesium 1  03/01/20 21 Hypertension and Diet ⮚ Dietary Approaches to Stop Hypertension (DASH) eating plan: oIncreased fruits/vegetables ♦ Increases potassium intake oIncreased whole grains ♦ Increases magnesium intake oLow fat dairy ♦ Increases calcium intake oOther recommendations: ♦ Lower saturated fat Diet and lifestyle changes to prevent/control hypertension ⮚ Other dietary changes: o sodium intake Avoid or limit processed foods, fast foods ⮚ Lifestyle: oAttain or maintain healthy body weight oPhysical activity 1