SM_187a: Body Fluid Compartments, Osmosis, and Basic Kidney Functions Flashcards
_____ of body fluid is intracellular, while _____ is extracellular
2/3 of body fluid is intracellular, while 1/3 is extracellular
(extracellular includes interstitial and plasma)
K+ predominates in ______ fluid
K+ predominates in intracellular fluid
Na+ predominates in ______ fluid
Na+ predominates in extracellular fluid
Small hydrophobic molecules ______ through the membrane
Small hydrophobic molecules freely diffuse through the membrane
(O2, CO2, N2, benzene)

Small uncharged polar molecules ______ through the membrane
Small uncharged polar molecules can diffuse through the membrane
H2O requires _______ to diffuse through the membrane
H2O requires an aquaporin (protein channel) to diffuse through the membrane

Charged and polar solutes require ______, ______, or ______ to diffuse through the membrane
Charged and polar solutes require channels, transporters, or pumps to diffuse through the membrane
(ions and large uncharged polar molecules such as amino acids, glucose, and nucleotides)

Passive transport is driven by _____, while active transport requires ______
Passive transport is driven by gradients, while active transport requires metabolic energy (usually ATP)

Driving forces for diffusion are ______ and _______
Driving forces for diffusion are diffusion pressure (concentration gradient) and membrane potential (electrical gradient)

Water moves across a semipermeable membrane toward the direction of ______
Water moves across a semipermeable membrane toward the direction of higher solute concentration

Osmotic pressure is proportional to _______
Osmotic pressure is proportional to number of particles in solution
(an osmole is a unit of measure of osmotically active solute molecules)
Osmolality is expressed as ______
Osmolality is expressed as number of osmoles per kg of water
Serum osmolality can be estimated by:
Serum osmolality can be estimated by
2 * serum Na (mEq/L) + glucose (mg/dL) / 18 + BUN (mg/dL) / 2.8

Cells will _____ in hypotonic solution
Cells will swell in hypotonic solution
(RBCs will dessicate)
Cells will _____ in isotonic solution
Cells will not change in side in isotonic solution
Cells will _____ in hypertonic solution
Cells will shrink in hypertonic solution
(RBCs will lyse)
Describe assumptions of the two chamber model to assess fluid losses and gains
- Intracellular osmolality = extracellular osmolality
- Water moves freely across membranes
- Solutes (NaCl, NaHCO3, mannitol) do not move across membranes
Describe the approach to assessing fluid losses and gains
- Identify change in ECF volume and osmolality - ∆ in solute and which compartment, ∆ in water
- Anticipate change in ECF osmolality
- Predict water movement between ECF and ICF
Isosmotic fluid loss (secretory diarrhea)
- ECF volume:
- EFC osmolality:
- ICF volume:
- ICF osmolality:
Isosmotic fluid loss (secretory diarrhea)
- ECF volume: decreases
- EFC osmolality: no change
- ICF volume: no change
- ICF osmolality: no change

Isosmotic fluid loss occurs in ______
Isosmotic fluid loss occurs in secretory diarrhea

Pure water loss (dehydration, such as insensible water loss or diabetes insipidus)
- ECF volume:
- EFC osmolality:
- ICF volume:
- ICF osmolality:
Pure water loss (dehydration, such as insensible water loss or diabetes insipidus)
- ECF volume: decreases
- EFC osmolality: increases
- ICF volume: decreases more than ECF volume
- ICF osmolality: increases

Pure water loss (dehydration) occurs in ______ and ______
Pure water loss (dehydration) occurs in insensible water loss and diabetes insipidus

Hypoosmotic fluid loss (excessive sweating, diuretics)
- ECF volume:
- EFC osmolality:
- ICF volume:
- ICF osmolality:
Hypoosmotic fluid loss (excessive sweating, diuretics)
- ECF volume: decreases more than ICF
- EFC osmolality: increases
- ICF volume: decreases
- ICF osmolality: increases

Hypoosmotic fluid loss occurs in ______ and ______
Hypoosmotic fluid loss occurs in excessive sweating and diuretics

Summarize the effects of different types of fluid loss

Isosmotic volume expansion (intravenous 0.9% NaCl: normal saline)
- ECF volume:
- EFC osmolality:
- ICF volume:
- ICF osmolality:
Isosmotic volume expansion (intravenous 0.9% NaCl, normal saline)
- ECF volume: increases
- EFC osmolality: no change
- ICF volume: no change
- ICF osmolality: no change

Isosmotic volume expansion occurs with _____
Isosmotic volume expansion occurs with intravenous 0.9% NaCl (normal saline)

Hypoosmotic volume expansion (intravenous 0.45% NaCl: half normal saline)
- ECF volume:
- EFC osmolality:
- ICF volume:
- ICF osmolality:
Hypoosmotic volume expansion (intravenous 0.45% NaCl: half normal saline)
- ECF volume: increases more than ICF volume
- EFC osmolality: decreases
- ICF volume: increases
- ICF osmolality: decreases

Hypoosmotic volume expansion occurs with ______
Hypoosmotic volume expansion occurs with intravenous 0.45% NaCl (half normal saline)

Acute water intoxication (oral, not IV)
- ECF volume:
- EFC osmolality:
- ICF volume:
- ICF osmolality:
Acute water intoxication (oral, not IV - pure water)
- ECF volume: increases
- EFC osmolality: decreases
- ICF volume: increases more than ECF volume
- ICF osmolality: decreases

Acute water intoxication occurs with _____
Acute water intoxication occurs with oral intake of pure H2O

Hyperoosmotic volume expansion (intravenous 3% NaCl)
- ECF volume:
- EFC osmolality:
- ICF volume:
- ICF osmolality:
Hyperoosmotic volume expansion (intravenous 3% NaCl)
- ECF volume: increases
- EFC osmolality: increases
- ICF volume: decreases
- ICF osmolality: increases

Hyperoosmotic volume expansion occurs with _____
Hyperoosmotic volume expansion occurs with 3% NaCl

Summarize the effects of the different types of fluid gain

Describe the basic functions of the kidney
- Waste management: nitrogenous wastes, acid (H+)
- Fluid and electrolyte balance: water, acid-base, K+, Ca2+, Mg2+
- Regulation of extracellular fluid volume: regulation of blood pressure, Na+ balance
- Endocrine: RAAS, natriuretic peptides, PTH, vitamin D, erythropoietin
- Drug and hormone elimination: elimination of small peptides, clearance of insulin and other hormones, drug clearance