Body Fluids and Electrolytes PDF

Body Fluids and Electrolytes 1 Learning Objectives: • Identify and describe daily intake and output of water an d maintenance of water balance. • List and describe of body fluid compartments as intra‐cell ular fluid (ICF), Extra‐cellular fluid (ECF), interstitial fluid, trans‐cellular fluid, and...

Body Fluids and Electrolytes 1 Learning Objectives: • Identify and describe daily intake and output of water an d maintenance of water balance. • List and describe of body fluid compartments as intra‐cell ular fluid (ICF), Extra‐cellular fluid (ECF), interstitial fluid, trans‐cellular fluid, and total body water (TBW). • Describe the composition of each fluid compartment, in t erms of volume and ions and represent them in graphic f orms. • Describe the physiological and pathological factors influe ncing the body fluid. 2 Composition of the human body: A. Body Water: The human body made mainly of water, which consistutes about 60% of body weight in the adult, however the amount of water varies with age. and the amount of water is change with age zhmara grng nea bo labar krdn Male (%) At birth Children and adolescents 18-20 years 20-40 years 40-60 years Over 60 years 82 70 59 61 55 52 Female (%) 82 70 57 51 47 46 3 Composition of the human body: B. Protein: Is the second largest component in the human body, largest amount found in skeletal muscle. C. Fat: the human body The third largest component in lean individual. It is found in adipose tissue 4 Composition of the human body: D. Minerals: Minerals, present in the human body in relatively small quantities with the exception of calcium. (Found in bones) Minerals and electrolytes are found in the body fluids in minute concentrations, which are closely regulated to maintain the composition of the internal environment 5 The body fluids: • Total body water (TBW): consititutes 55-60% of the body weight in young men and 45-50% in young women. Why the percentage is lower in women? • The TBW is distributed as follows: Muscle (50%) Skin (20%) Other organs (20%) Blood (10%) 6 The body fluids: • Infants have low body fat, low bone mass, and are 73% or mo re water. • Total water content declines throughout life. • Healthy males are about 60% water; healthy females are arou nd 50% – This difference reflects females’: • Higher body fat • Smaller amount of skeletal muscle • In old age, only about 45% of body weight is water. 7 The body fluids: • The water content of the body is divided into two compartments. 1) Intracellular compartment: Contained within the cell, represent approximately 67% of the total body water, 40% of total body weight. 2) Extracellular Compartment: Contained within the vessels of the cardiovascular system, is the remaining 33% of the total body water, about 20 % of total body weight, 8 The Composition of the Human Body: 9 Extracellular fluid (ECF) The ECF compartments has several subcompartments: 1. part Plasma, the fluid portion of the blood, represents approximately 25% of the ECF. Blood volume, approximately 80 ml/kg of body weight (8%). 10 Extracellular fluid (ECF) 2. Interstitial fluid (ISF), is contained in a gel-like extracellular matrix. ISF sourrounds all cells except blood cells and includes Lymph (2-3%) of total body weight The ISF represent approximately 15% of the total body weight and 75% of the ECF. 11 Extracellular fluid (ECF) 3. Transcellular fluid volume, is about 1 L, occupies approximately 15 ml/kg of body weight (1.5%). * Represents fluid in the lumen of structures lined by epithelium and includes digestive secretions, sweat, CSF, pleural, peritoneal, synovial, intraocular, pericardial fluids, bile, thyroid, and cochlea. 12 Constitutes of extracellular and intracellular fluids: Plasma Interstitial Intracellular (mOsm/L H2O) (mOsm/L H2O) (mOsm/L H2O) just for information Na+ 142 139 14 K+ 4.2 4.0 140 1.3 1.2 0 0.8 0.7 20 108 108 4 24 28.3 10 2 2 11 0.5 0.5 1 Ca++ + Mg Cl - HCO3HPO4-, H2PO4- SO4Phosphocreatine 45 Carnosine 14 Amino acids 2 2 8 Creatine 0.2 0.2 9 Lactate 1.2 1.2 1.5 Adenosine triphosphate 5 Hexose monophosphate 3.7 Glucose 5.6 5.6 Protein 1.2 0.2 4 4 4 4 4.8 3.9 10 Total mOsm/L 301.8 300.8 301.2 Corrected osmolar activity (mOsm/L) 282.0 281.0 281.0 Total osmotic pressure at 37°C (mm Hg) 5443 5423 5423 Urea Others 13 The major body fluid compartment and membranes separate them 14 • The plasma and interstitial fluid are separated only by highly permeable capillary membranes, their ionic composition is similar but protein is higher in the plasma. • the intracellular fluid is separated from extracellular fluid by a cell membrane that is highly permeable to water but not to most of the electrolytes in the body. 15 Solute Overview: Intracellular vs. Extracellular • • • Ionic composition very different Total ionic concentration very similar Total osmotic concentrations virtually identical 16 Water Steady State: • Amount ingested = amount eliminated. • Pathological losses: Vascular bleeding. Vomiting. Diarrhea. 17 Factors That Affect TBW: Physiological factors: • • • • • Age Sex Body fat Climate Physical activity Pathological factors: • Vomiting • Diarrhea • Diseases with excessive loss of water (DM, excessive sweating,…. • Blood loss 18 Definitions: • Volume: the general clinical terms for volume abnormalities are dehydration and overhydration. Both conditions are associated with a change in ECF volume. • Concentration: Osmolarity refers to the number of solute particles per liter of solution, and Osmolality refers to the number of solute particles per kilogram of water. • Tonicity: The effect of a solution on the osmotic movement of H20. according to association and function ion cl ---} 2 atom cl + ba --} 3 atom but it all one molar 19 Tonicity • • • Isotonic: – Equal tension to plasma. • RBCs will not gain or lose H20. Hypotonic: – Osmotically active solutes in a lower osmolality and osmotic pressure than plasma. • RBC will hemolyse. Hypertonic: – Osmotically active solutes in a higher osmolality and osmotic pressure than plasma. • RBC will crenate. 20 21