Exam 3 Lecture: Body Fluid and Osmolarity Flashcards
What is the main ECF ion?
Na
What is the main determinant of ECF osmolarity?
Na
What will an increase in the amount of ECF Na do to the ECF volume?
it will increase it
What will a decrease in the amount of ECF Na do to the ECF volume?
it will decrease it
Where is the only site of ECF Na regulation?
the kidney
What is osmolarity?
the concentration of osmotically active things
How does the kidney regulate ECF osmolarity?
by changing ECF Na concentration
How does the kidney regulate ECF volume?
by changing ECF Na amount
What does high Na concentration in the ECF lead to?
an increase in ECF osmolarity and cause water movement out of cells; cells will shrink
What does low Na concentration in the ECF lead to?
a decrease in ECF osmolarity and cause water to move into the cells; cells will swell
What do the terms hypo- and hypernatremia define?
the ECF Na concentration
What is hyponatremia?
low Na concentration in the ECF
What is hypernatremia?
high Na concentration in the ECF
What are some symptoms of hypernatremia?
rupture of cerebral vessels/hemorrhage, muscle weakness, behavioral changes/ataxia, coma leading to death
What are some conditions that lead to hypernatremia?
- limited access to water supply
- diabetes insipidus
- loss of hypotonic fluids
- salt poisoning
What are some symptoms of hyponatremia?
cerebral/pulmonary edema, muscle weakness, uncoordination and seizures
What are some conditions that lead to hyponatremia?
- hyperglycemia
- GI fluid loss/third space fluid loss
- congestive heart failure
- liver failure
- psychogenic polydispia
How is ECF Na concentration controlled?
by adjusting ECF water levels
What does adding or subtracting Na into the ECF do?
it affects the ECF volume because water will ultimately follow it
What is the mechanism used for adding water to the ECF?
a combination of increased ADH release and thirst
What are ECF osmolarity changes detected by and what do the detectors due?
sensed by osmoreceptors that either shrink or swell the hypothalmus which triggers or prevents ADH realease from the posterior pituitary