Fluid and Electrolytes

• Homeostasis


  Balance depends on several physiologic processes
• Diseases and daily factors can create imbalances
• Water


  60% healthy adult weight
• Fat tissue


  Free of muscles
• Muscle tissue


  Has significant amount of water
• Intracellular

  Within the cell, about 2/3 adult body fluid, vital for cell functioning, medium for metabolic processes
• Extracellular

  Outside the cell, 1/3 body fluid, includes intravascular or plasma, interstitial, lymph and transcellular fluid, carries oxygen and nutrients to and waste away from cells
• Total body fluid

  • 40L
  • Cell fluid - 25L
  • Plasma - 3L
  • Interstitial and transcellular fluid - 12L
  • Extracellular Fluid - 15L
• Composition of Body Fluid

  Oxygen, nutrients, waste products, and Ions
• Electrolytes

  Cation and anions, measured in milliequivalents (mEq)
• Extracellular - sodium, chloride, and bicarbonate

  Intracellular - potassium, magnesium, phosphate, and sulfate
• Movement of body fluids and electrolytes

  -selectively permeable

  Vary degrees of ease of movement

  -solutes

  -crystalloids

  -solvent

  -osmolarity
• Solutions

  • isotonic
  • hypertonic
  • hypotonic
• Osmotic pressure

  Colloid osmotic pressure (oncotic)
• Diffusion

  • Two solutes of different concentrations separated by semipermeable membrane
• Osmosis

  -water moves across cell membrane

  Filtration

  -filtration pressure

  -hydrostatic pressure
• Active transport - movement from less to high concentration across cell membrane
• Fluid intake 2500l thru fluids and food

  Thirst mechanism

  Fluid output

  • Urine
  • Feces
  • Insensible fluid loss
  • Skin and lungs
  • Obligatory losses
• Regulating body fluids

  Maintaining homeostasis

  • Kidneys
  • Hormones
  • Anti-diuretic hormones
  • Renin angiotensin aldosterone system
  • Atrial natriuretic factor
• Regulating electrolytes

  Maintaining fluid balance

  Contributing to acid base regulation

  Facilitating enzyme reactions

  Transmitting neuromuscular reactions

  • Obtained through diet excreted in urine
• To regulate homeostasis

  Regulate acid and bases
• Maintained by: 7.35 and 7.45

  Buffers

  • Prevents excessive change in pH
  • Other buffers:
  • Plasma proteins
  • Hemoglobin
  • Phosphate

  Respiratory regulation

  Renal regulation

  Imbalance acidosis or alkalosis
• Renal regulation

  • Kidneys regulated by selectively excreting and conserving bicarbonate and hydrogen ions
  • Slower to respond to imbalance
• Factors

  • Age
  • Sex and body size
  • Environmental Temperature
  • Lifestyle
  • Diet
  • Exercise
  • Stress
  • Alcohol consumption
• Disturbances

  • Renal disease
  • Cardiovascular disease
  • DM, Cancer, COPD
  • Confusion
  • Nausea vomiting
  • Burns
  • Medications
• Fluid imbalances

  • Isotonic loss or gain of water in equal proportions
  • Osmolar
  • Loss or gain of water only
• Fluid deficit

  • Hypovolemia
  • Isotonic loss of water and electrolytes
  • Third space syndrome
• Fluid excess

  • Isotonic gain
  • Edema
• Dehydration

  • Loss of water with excess sodium.
• Overhydration

  • Gain of only water, low serum and sodium levels
• Respiratory or metabolic imbalance

  Lungs

  • Carbonic acid

  Kidneys

  • Bicarbonate and hydrogen ion

  Compensation

  • Health regulatory system