Water balance lecture Flashcards
What are the two properties of a solute particle’s ability to cross membranes, and what are their abbreviations?
Sieving - S (ability to go through)
Reflection - (sigma) inability to go through
what’s the difference between osmolarity and tonicity
for something to have tonicity, it must be reflective
what are osmoconformers and osmoregulators?
osmoconformers are those organisms that adapt to the osmotic environment in which they live
osmoregulators maintain their own internal osmotic environment
dysnatrimias are what kind diseases?
denominator diseases (meaning the altered state deals with the denominator of the common concentration equation - namely water)
what is cellular defense in regards to homeostasis
the cell level regulation that defends against changes in the microenvironment
what are the responses to a water deficit in the body?
water consumption and water generation
what is the mechanism for water generation in humans?
the ADH-renal axis
where is ADH produced?
surpaoptic and the paraventricular nucleus of the hypothalamus
osmoreceptor control of ADH secretion is characterized by specificity or power?
specificity, it can recognize changes of less than 1%; more effective than baroreceptor response when deviations from norm are minimal
baroreceptor control of ADH secretion is characterized by specificity or power?
power, it overrides the contrary signal from the osmoreceptors starting at 8% volume depletion
what are the two proponents of thirst?
hypertonicity and decreased circulating volume
what’s the relationship between thirst threshold and ADH release threshold?
thirst threshold is above ADH release threshold
thirst can be suppressed by which mechanisms?
volume expansion, hypotonicity or the oropharyngeal reflex
what are the upper and lower limits for concentration and volume of urine?
20L/200mL
<50 mOsm/1200 mOsm
what is the critical nephron segment for water balance?
the collecting tubule
