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What is the impact on extracellular and intracellular fluid volumes when a hypertonic sodium chloride solution is administered to a patient with normal osmolarity?
What is the impact on extracellular and intracellular fluid volumes when a hypertonic sodium chloride solution is administered to a patient with normal osmolarity?
The extracellular fluid volume increases while the intracellular fluid volume remains constant, due to the hypertonic solution drawing water out of the cells.
Explain how plasma sodium concentration is related to fluid balance mechanisms in the body.
Explain how plasma sodium concentration is related to fluid balance mechanisms in the body.
Plasma sodium concentration reflects the balance of sodium and water in the extracellular fluid, with normal levels at 142 mEq/liter crucial for maintaining osmotic pressure and hydration.
What are the physiological consequences of hyponatremia?
What are the physiological consequences of hyponatremia?
Hyponatremia can lead to cellular swelling due to excess water in the extracellular fluid, potentially causing neurological complications.
How does the Donnan effect influence the distribution of ions in body fluid compartments?
How does the Donnan effect influence the distribution of ions in body fluid compartments?
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What are the differences in the causes of hyponatremia and hypernatremia?
What are the differences in the causes of hyponatremia and hypernatremia?
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What concept explains the pressure required to stop osmosis in a selectively permeable membrane?
What concept explains the pressure required to stop osmosis in a selectively permeable membrane?
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How does the concentration of solutes relate to osmotic pressure?
How does the concentration of solutes relate to osmotic pressure?
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What formula can be used to calculate osmotic pressure, and what does each variable represent?
What formula can be used to calculate osmotic pressure, and what does each variable represent?
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How does the dissociation of sodium chloride in solution affect osmotic pressure calculations?
How does the dissociation of sodium chloride in solution affect osmotic pressure calculations?
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Describe the impact of the Donnan effect on ions within body fluid compartments.
Describe the impact of the Donnan effect on ions within body fluid compartments.
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What is the effect of placing a cell in a hypotonic solution?
What is the effect of placing a cell in a hypotonic solution?
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Define isotonic solutions and give two examples.
Define isotonic solutions and give two examples.
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How does a hypertonic solution affect cell volume?
How does a hypertonic solution affect cell volume?
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What are the main factors affecting extracellular and intracellular fluid volumes?
What are the main factors affecting extracellular and intracellular fluid volumes?
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Why do intracellular and extracellular fluid osmolarities usually remain equal?
Why do intracellular and extracellular fluid osmolarities usually remain equal?
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What medical condition might result from an osmolarity of 320 mOsm/l in a patient?
What medical condition might result from an osmolarity of 320 mOsm/l in a patient?
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Describe the Donnan effect and its impact on ion distribution.
Describe the Donnan effect and its impact on ion distribution.
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Explain the importance of maintaining fluid balance in clinical settings.
Explain the importance of maintaining fluid balance in clinical settings.
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Study Notes
Lecture 18: Bodily Fluid Compartments
- Bodily fluid is essential for homeostasis
- Kidneys control many functions, including regulating body fluid volume, fluid constituents of extracellular fluid, acid-base balance, and fluid exchange between extracellular and intracellular compartments
- Water intake comes from ingested liquids/food and the oxidation of carbohydrates
- Water loss occurs by insensible water loss (through skin, humidification of inspired air, sweat, feces, urine). Kidneys are crucial for controlling water loss
- Total body fluid is divided into extracellular (blood plasma and interstitial fluid), transcellular (synovial, peritoneal, pericardial, intraocular), and intracellular fluid
- A 70 kg person contains approximately 42 liters of water (60%) and varies based on age, sex and obesity.
- Plasma is 60% of blood, RBCs is approximately 40%
- Plasma and interstitial fluid compositions are similar, except interstitial fluid typically has low protein concentration
- Osmosis is the diffusion of water through a selectively permeable membrane to equalize solute concentration. An osmole is the total number of particles in a solution
- Osmolality is osmoles/kg solution, whereas Osmolarity is osmoles/liter solution
- Osmotic pressure is proportional to osmolarity and equals CRT (C = concentration, R = ideal gas constant, T = absolute temperature (in Kelvin), and II = osmotic pressure).
- A 0.9% sodium chloride solution has an osmolarity of 286 mOsm/L
- Isotonic solutions have an osmolarity of 280 mOsm/L (neither shrink or swell the cell)
- Hypotonic solutions have an osmolarity less than 280 mOsm/L (cause the cell to swell)
- Hypertonic solutions have an osmolarity greater than 280 mOsm/L (cause the cell to shrink)
Measuring Fluid Volumes
- Total body water - add a bolus of radioactive water, measure concentration after a few hours
- Extracellular fluid volume - add a bolus of radioactive sodium, measure concentration after a few hours
- Intracellular fluid volume - total body water minus extracellular fluid volume
- Plasma volume - add a bolus of radioactive serum albumin, measure concentration after a few hours
- Interstitial fluid volume - extracellular fluid volume minus plasma volume
Fluid Regulation in Abnormal States
- Abnormalities in composition/volumes of body fluids are common in serious illness
- Factors affecting volume include water ingestion, dehydration, intravenous infusions, fluid loss from GI tract, sweat, kidneys
- Water moves rapidly across cell membranes, making intracellular and extracellular osmolarities nearly equal
- Important examples include patient with water deficit, and fluid regulation in abnormal states (hyponatremia, hypernatremia, edema)
Edema
- Edema is the presence of excess fluid in the body, predominantly in the extracellular space
- Conditions involve intracellular swelling or extracellular swelling
- Intracellular swelling: metabolic system depression, inadequate nutrient delivery
- Extracellular swelling conditions: abnormal leakage (fluid from plasma to interstitial space), failure of lymphatic system (circulatory failure, abnormal retention of salt and water)
Fluid Regulation in Abnormal States
- Edema related to heart failure, kidney failure related to salt/water retention, and edema caused by decreased plasma proteins (renal abnormalities, cirrhosis of the liver)
- Prevention of edema depends on low compliance of interstitium, increased lymph flow, and washdown of interstitial fluid protein.
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Description
This quiz covers key concepts from Lecture 18, focusing on bodily fluid compartments essential for homeostasis. It includes the roles of kidneys in regulating fluid balance, water intake and loss, and the composition of various body fluids. Test your understanding of how the body manages its fluid needs and the impact of various factors on bodily fluid levels.
