🌊 PPT

• What is the daily intake of water for the body?

  ~2300 ml/day
• What are the two major sources of water intake?

  Ingested liquids and food, and synthesis
• How much water is synthesized in the body by oxidation of carbohydrates?

  ~200 ml/day
• What is insensible water loss?

  Continuous water loss by evaporation and diffusion
• How much water is typically lost in sweat daily?

  ~100 ml/day
• What factors influence the amount of water lost by sweating?

  Physical activity and environmental temperature
• How much water can be lost in sweat during heavy exercise?

  1 to 2 L/hour
• How much water is lost in feces daily?

  ~100 ml/day
• What can increase water loss in feces?

  Severe diarrhea
• Where does the remaining water loss from the body occur?

  In urine excreted by the kidneys
• What percentage of total body weight is water in infants?

  ~75%
• How does body water content change with age?

  Total water content declines throughout life
• What is the average blood volume of adults?

  ~5L
• What percentage of blood is plasma?

  ~60%
• What is the main contributor to the osmolality of blood?

  Na
• What is the difference between osmolality and osmolarity?

  Osmolality is per kg of water; osmolarity is per liter
• What is osmotic pressure?

  The pressure required to stop osmosis
• What does van’t Hoff law state?

  Osmotic pressure depends on solute particles and temperature
• How does the concentration of solute affect osmotic pressure?

  Higher solute concentration means greater osmotic pressure
• What is the difference between osmolarity and tonicity?

  Osmolarity measures solute concentration; tonicity measures osmotic pressure gradient
• What are the three types of solutions based on tonicity?

  Isotonic, hypotonic, hypertonic
• What happens to cell volume in isotonic solutions?

  No change in cell volume occurs
• What is the effect of hypertonic solutions on cells?

  Cells shrink due to water loss
• What is the effect of hypotonic solutions on cells?

  Cells swell due to water gain
• How does lymph flow act as a safety factor against edema?

  Lymph flow can increase 10- to 50-fold
• What is hyponatremia?

  Reduced plasma Na concentration
• What is hypernatremia?

  Elevated plasma Na concentration
• What is the role of interstitial gel in preventing fluid accumulation?

  It binds fluid in a meshwork, preventing flow
• What is the most common clinical cause of interstitial fluid accumulation?

  Excessive capillary fluid filtration
• What causes extracellular edema?

  Excess fluid accumulation in extracellular spaces
• What is the average plasma sodium concentration?

  About 142 mEq/L
• What happens to interstitial fluid protein concentration as lymph flow increases?

  It decreases as proteins are carried away
• What is the significance of the proteoglycan filaments in tissues?

  They act as spacers and prevent rapid fluid flow
• What can cause effusion in potential spaces?

  Lymph blockage or excessive capillary filtration
• What is the role of washdown of interstitial fluid protein?

  It reduces interstitial fluid colloid osmotic pressure
• What are the main objectives of studying fluid intake and output?

  • Understand fluid intake and output
  • Learn about body fluid compartments
  • Explore fluid exchange and osmotic equilibrium between ICF and ECF
  • Identify clinical abnormalities of fluid volume regulation
  • Study edema and fluids in potential spaces of the body
• What are the safety factors that prevent edema?

  1. Low compliance of interstitium with negative pressure
  2. Increased lymph flow (10- to 50-fold)
  3. Washdown of interstitial fluid protein concentration
• What are the constituents of extracellular and intracellular fluids?

  • ECF: Interstitial fluid and plasma
  • ICF: Fluid inside cells
  • Similar ionic composition between plasma and interstitial fluid
  • Higher protein concentration in plasma
• What is the difference between isosmotic, hyperosmotic, and hypo-osmotic fluids?

  • Isosmotic: Same osmolarity as cell
  • Hyperosmotic: Higher osmolarity than cell
  • Hypo-osmotic: Lower osmolarity than cell
• What are the effects of isotonic, hypotonic, and hypertonic fluids on cells?

  • Isotonic: No change in cell volume
  • Hypotonic: Cells swell
  • Hypertonic: Cells shrink