RP1: Body Fluids and Renal Function Flashcards
What do imbalances in Na+ cause?
Imbalance changes vascular and total body volumes
What do imbalances in K+ cause?
Imbalance alters cardiac and neural functions
What do imbalances in Ca++ cause?
Imbalance alters skeletal muscle, cardiac, neural function and bone structure
What do imbalances in H+ cause?
Imbalance alters multiple systems
Total body water volume is what percent of body weight?
60%
What percent of body weight is intracellular fluid?
40%
What percent of body weight is extracellular fluid?
20%
What makes up the extracellular fluid?
interstitial fluid
plasma
What percent of body weight is plasma?
4-5%
What electrolytes are high in the ECF?
Na+
Ca++
Cl-
HCO3-
Glucose
What electrolytes are high in the ICF?
K+
Mg++
H+
amino acids
What anions make up 90% of the total ECF osmolarity?
Na+ and Cl-
Adding hypertonic solution
- increase ECF volume
- increase ECF osmolarity
- decrease ICF volume
- increase ICF osmolarity
Adding hypotonic solution
- decrease ECF osmolarity
- increase ECF volume
- increase ICF volume
- decrease ICF osmolarity
Adding isotonic solution
How would ECF and ICF volume and osmolarity change in an individual that has lost a hypotonic solution from ECF (sweating)?
- increase in ECF osmolarity
- decrease in ECF volume
- increase in ICF osmolarity
- decrease in ICF volume
What are the causes of intracellualr edema?
- Hyponatremia.
- Decreased metabolism (blood flow): Na+/K+ pump failure (Donnan Effect)
- Inflammation (infection, burns) – increased membrane permeability and leakage.
What happens if the ECF volume is too low?
- volume contraction
- hypotension
- organ hypoperfusion
What happens if the ECF volume is too high?
- edema
- ascites
- pleural effusions
- hypertension
What are the three types of hyponatremia?
- Dehydration (increased NaCl loss due to vomiting, diarrhea, renal disease, addison’s disease, diuretics)
- Overhydration (excess H2O retention, inappropriate ADH secretion)
- Low solute intake (decreases NaCl from diet)
What is acute hyponatremia?
➢ Rapid decrease in [Na+] ECF
➢ Caused by loss of Na+ or excess H2O
➢ H2O into the cells
➢ Swelling of the brain tissue.
What is chronic hyponatremia?
➢ Gradual decrease in [Na+]ECF
➢ This stimulates transport of Na+, K+, and organic solutes out of the cells
➢ This causes water diffusion out of the cells
➢ With chronic hyponatremia, the brain swelling is attenuated by the transport of solutes from the cells.
What can happen if you correct hyponatremia too fast?
osmotic demyelination
What causes extracellular edema?
➢ Increased capillary filtration (most common; congestive heart failure)
➢ Failure of lymphatics to return interstitial fluid to circulation (lymphedema)
What are the absorptive starlings forces?
- plasma colloid osmotic pressure (Nc)
- interstitial fluid pressure (Pisf)
What are the filtration starlings forces?
- capillary pressure (Pc)
- interstitial colloid osmotic pressure (Nisf)
If you increase Kf what happens to filtration?
filtration is increased
What is the equation for filtration rate?
Filtration Rate = Kf((Pc + Nif) – (Pif + Nc))
What starlings forces are responsible for extracellular edema?
➢Capillary permeability (Kf)
– Inflammation
– Burns
– Ischemia
➢Increased capillary hydrostatic pressure (Pc)
– Heart failure
– Renal disease
➢Decreased capillary colloid osmotic pressure (Nc)
– Renal loss (nephrotic syndrome)
– Liver disease
What are the changes in the following variables after giving
2.0 liters of water i.v.?
Extracellular Fluid Volume
Extracellular Fluid Osmolarity
Intracellular Fluid Volume
Intracellular Fluid Osmolarity
Extracellular Fluid Volume - increase
Extracellular Fluid Osmolarity - decrease
Intracellular Fluid Volume - increase
Intracellular Fluid Osmolarity - decrease
