Urinary 4

• Chemical bonds are what holds the atoms together by chemical forces. The 3 types of chemical bonds are covalent bonds, ionic bonds and hydrogen bonds
• Covalent bonds are strong bons that hold atoms together by sharing electron pairs
• Ionic bonds are less strong than covalent bonds. These bonds are formed between positive and negative ions where one atom gives up one electron and the other atom takes up the electron
• Ionic bonds are formed by the attraction of oppositely charged ions
• Electrolytes are compounds that can breakup or dissociate due to their ionic bond. Dissociated particles of an electrolyte are ions, they carry an electrical charge
• Glucose is a non electrolyte since it is a compound that cannot breakup or dissociate due to their covalent bonds
• Total body water is the percentage of body weight of water. It varies between 45% and 75%. This difference is due to different factors such as age, gender and fat content of the body since fat is hydrophobic.
• Total body water:

  • infants: 75%
  • adolescents: 60%
  • old people: 45% due to decrease in muscle and increase in fat as well as decreased ability from kidneys to make concentrated urine
• Body fluid compartments are intracellular fluid (water in cells) and extracellular fluid (plasma, lymph, joint fluid, cerebrospinal fluid, eye ball, interstitial fluid)
• Important cations (positive charge) are Na+, K+, Ca 2+, Mg 2+. These are minerals from your diet
• Intracellular fluid has way more potassium and way less sodium. Plasma has more protein in it than interstitial fluid
• Water entering the body usually equals the total volume leaving the body
• Under normal conditions, homeostasis of the total volume of water is maintained by mechanisms that adjust urine volume (output) or fluid intake
• The thirst center in the brain has osmoreceptors. These are cells that detect an increase in solute concentration in extracellular fluid causes by water loss. Osmoreceptors then generate signals like dry mouth, decreased saliva production and ADH
• Two factors determine urine volume: glomerular filtration rate and rate of water reabsorption by renal tubules. GFR stays constant therefore tubular reabsorption adjusts urine volume to fluid intake
• Amount of ADH and aldosterone regulates amount of water reabsorbed by the kidneys
• ADH and aldosterone maintain normal levels of both sodium and potassium in interstitial fluid. If sodium needs to be conserved, the kidney can produce a sodium free urine.
• Dehydration happens when fluid output exceeds fluid intake and a fluid imbalance develops. The severity of dehydration can be measured as perecentage of body weight lost in water. The biggest dehydration clinical manifestation is turgor.
• 7 standard solutions used in parenteral therapy for dehydration are:

  • carbohydrate in water
  • carbohydrate in various strengths of saline
  • normal saline
  • potassium solutions
  • ringer’s solution
  • lactate solution
  • ammonium chloride solution
• Parenteral therapy is the administration of nutrients, fluids and electrolytes by injection (IV). Parenteral solutions are generally given to meet current needs for nutrients and replaces losses (eg: dehydration). everything given must be isotonic
• Edema is the presence of abnormally large amounts of fluid in the interstitial space of the body. It is caused by disturbances of factors that control fluid exchange between blood plasma and interstitial fluid
• Factors that control fluid exchange

  • retention of electrolyes in the extracellular fluid
  • increase in BP
  • decrease in concentration of plasma protein caused by infection, burn or shock
• Fluid and electrolyte disorders

  • hypovolemia: dehydration
  • hypervolemia: increased fluid volume
  • hyponatremia: decreased plasma sodium
  • hypernatremia: increased plasma sodium
  • hypokalemia: dereased plasma potassium
  • hypekalemia: increased plasma potassium