Fluid & Electrolyte Balance 1 PDF

Fluid, Electrolyte Balance 1 AND BALANCE OF POTASSIUM DR SADIA HAROON UGS MODULE SECOND YEAR MBBS DATE 20.7.24 © 2011 Pearson Education, Inc. Learning objective a. Identify routes of water balance from the body. b. Describe a fluid balance and imbalan...

Fluid, Electrolyte Balance 1 AND BALANCE OF POTASSIUM DR SADIA HAROON UGS MODULE SECOND YEAR MBBS DATE 20.7.24 © 2011 Pearson Education, Inc. Learning objective a. Identify routes of water balance from the body. b. Describe a fluid balance and imbalance c. Explain dehydration and its effect on the osmotic concentration of plasma. d. What are functions of potassium. e. And its abnormalities Water & Body Fluids Functions of water: Transport Structural support for molecules Participates in metabolic reactions Solvent Lubricant & shock absorber Body temperature regulation Maintains blood volume & blood pressure Water & The Body Fluids Water balance Intracellular fluid-within the cells Extracellular fluid-outside the cells Interstitial fluid Plasma Copyright 2005 Wadsworth Group, a division of Thomson Learning  FLUID CONTENT OF THE BODY Varies with age, sex, adipose tissue Females 45-50% TBW Males 50-60% TBW Infants 77% TBW Water & Body Fluids Water Balance -Intake/output = 2.5 liters/day -Regulated by hypothalamus & kidneys -Carefully controlled by: 1. Intake (liquid, foods, metabolic water) affected by thirst & satiety 2. Output (losses via kidneys, skin, lungs, feces) affected by blood salts, volume & blood pressure How The Body Regulates Blood Volume Copyright 2005 Wadsworth Group, a division of Thomson Learning Water & Body Fluids Recommendations: -Needs vary according to type of food eaten, temperature, humidity, activity level, etc. -General rule: 1–1.5 ml/kcal expended Example: if 2000 kcal “burned” then 2-3 liters suggested; >8 cups from fluids and the rest comes from food & metabolic water -Urine should be pale yellow -Caffeine & alcohol act as diuretics so not good water substitutes Fluid & Electrolyte Balance Electrolytes – salts that dissolve in water, forming ions Dissociation of salt in water Ions Cations- + charged particles Anions- - charged particles Electrolyte solution Copyright 2005 Wadsworth Group, a division of Thomson Learning Body Fluid Compartments Extracellular fluid (ECF) Called internal environment of body Surrounds cells and transports substances to and from them Types Plasma: Liquid part of whole blood Interstitial fluid: Surrounds the cells Transcellular fluid: Lymph, joint fluids, cerebrospinal fluids, eye humors Copyright © 2016 by Elsevier 11 BODY FLUID COMPARTMENTS  Extracellular fluid (ECF)  Called internal environment of body  Surrounds cells and transports substances to and from them  Types  Plasma: Liquid part of whole blood  Interstitial fluid: Surrounds the cells  Transcellular fluid: Lymph, joint fluids, cerebrospinal fluids, eye humors  Intracellular fluid (ICF)  Largest fluid compartment  Serves as solvent to facilitate intracellular chemical reactions ELECTROLYTES IN BODY FLUID COMPARTMENTS INTRACELLULAR EXTRACELLULAR POTASSIUM SODIUM MAGNESIUM CHLORIDE PHOSPHOROUS BICARBONATE Fluid & Electrolyte Balance Electrolytes – salts that dissolve in water, forming ions Dissociation of salt in water Ions Cations- + charged particles Anions- - charged particles Electrolyte solution Copyright 2005 Wadsworth Group, a division of Thomson Learning Mechanisms That Maintain Fluid Balance Overview of fluid balance Regulation of fluid output  Fluid output, mainly urine volume, adjusts to fluid intake  Antidiuretic hormone (ADH) from posterior pituitary gland acts to increase kidney tubule reabsorption of sodium and water from tubular urine into blood, thereby tending to increase ECF (and total body fluid) by decreasing urine volume (Figure 19-5)  mechanisms that adjust fluid intake.  As long as input and output are equal, the total amount of water in the body does not change.  The four main sources of water output in body are: water vapor lost when we exhale, sweat that evaporates from skin, urine output by the kidney, and water lost in the feces.. 15 Maintain Fluid Balance (Cont.) Regulation of fluid intake ECF electrolyte concentration influences ECF volume Increase in ECF increases ECF volume by increasing movement of water out of ICF and by increasing ADH secretion, which decreases urine volume Exchange of fluids by blood Capillary blood pressure pushes water out of blood, into interstitial fluid; blood protein concentration pulls water into blood from interstitial fluid; hence, these two forces regulate plasma and interstitial fluid volume under usual conditions The three main sources of fluid intake are: liquids we drink, water in the foods we eat, and water formed by catabolism of nutrients (cellular respiration). Copyright © 2016 by Elsevier 16 Fluid Imbalances  Dehydration (Figures 19-7 and 19-8)  Total volume of body fluids less than normal  Interstitial fluid volume shrinks first, and then if treatment is not given, ICF volume and plasma volume decrease  Dehydration occurs when fluid output exceeds intake for an extended period  Overhydration  Total volume of body fluids greater than normal  Overhydration occurs when fluid intake exceeds output  Various factors may cause this (e.g., giving excessive amounts of intravenous fluids or giving them too rapidly may increase intake above output) Copyright © 2016 by Elsevier 17 Fluid Imbalances (Cont.) Overhydration Water intoxication may result from rapidly drinking large volumes of water or giving hypotonic solutions to persons unable to dilute and excrete urine normally Copyright © 2016 by Elsevier 18 Electrolyte Imbalances Homeostasis of electrolytes Electrolyte balance related to “intake” and “output” of specific electrolytes Sodium imbalance Hypernatremia: Blood sodium level >145 mEq/L Hyponatremia: Blood sodium level 5.1 mEq/L Hypokalemia: Blood potassium level