Basics 25 & 30

• Two largest body fluids are water and electrolytes
• Four main functions of water in the body:

  • transport substances to and from cells
  • aid in heat regulating with perspiration
  • assist with H+ balance
  • serve as a medium for the enzymatic action of digestion
• The amount of water in the body is based on age, sex and health status
• infants and older adults are affected more quickly and seriously by small changes in fluid balance and can become rapidly dehydrated
• Hypervolemia: excess fluid volume in the body
• Water is critical to maintain homeostasis
• Electrolytes are minerals or salts that are dissolved in body fluid
• Electrolytes break up into ions (tiny particles with an electric charge) when in a solution
• cations: positively charged ions

  Anions: negatively charged ions
• For every cation in a fluid compartment there must be an anion so that balance is maintained
• The major source of electrolytes is diet
• Electrolyte Ranges:

  Soidum (135-145 mEq/L)

  Potassium (3.5-5.0 mEq/L)

  Calcium (8.4-10.6 mEq /dL)

  Magnesium (1.3-2.1 mEq /dL)

  Phosphate (3.0-4.5 mEq /dL)

  Chloride (96-106 mEq /L)

  Bicarbonate (22-26 mEq /L)
• Amino acids, glucose and fatty acids are nonelectrolytes
• Conditions that alter body fluid volume also alters plasma volume of the blood and can affect blood pressure and circulation
• Intracellular: within the cell
• Extracellular: outside the cell
• 3 types of Extracellular fluid:

  1. intravascular
  2. interstitial
  3. transcellular
• Dehydration: removal of water from tissue
• Hypovolemia: decreased volume of plasma
• the kidney is the main organ through which fluid excretion is achieved
• Increased ADH the renal tubules reabsorb more water and urine output decreases
• Diffusion: movement of particles from a high concentration to an area of lower concentration
• Osmosis: the movement of liquids across a membrane
• Isotonic: solution that is of equal concentration
• Hypertonic: a solution with greater concentration
• Hypotonic: solution with less concentration
• Water passes freely across cell membranes because of osmosis
• Filtration: movement of water and suspended substances outward through a semipermeable membrane in response to pressure
• Hydrostatic pressure: pressure exerted by fluid

  the pumping of the heart creates hydrostatic pressure within the capillaries
• Active transport may move substances from an area of lower concentration to an area of higher concentration
• Active transport can move

  • amino acids
  • glucose
  • iron
  • hydrogen
  • sodium
  • potassium
  • calcium

  through the cell membrane.
• The healthy kidney regulates fluid and electrolyte balance by regulating the volume and composition of ECF (extracellular fluid)
• Any seriously ill patient is at risk for a fluid and electrolyte imbalance
• A fluid imbalance occurs when the body has too little or too much water
• Water follows sodium in the body
• Diuretic therapy and gastrointestinal suction without fluid replacement are two treatments that can cause fluid deficit
• Dehydration is treated by fluid administration either orally or intravenously
• Skin turgor is a good test to determine dehydration
• Dehydrated infants may show evidence of sunken eyeballs and a depressed anterior fontanel
• Signs of over hydration:

  • weight gain
  • crackles in the lungs
  • slow bounding pulse
  • elevated blood pressure
  • possibly edema