IP1: Regulation of Extracellular Fluid Volume and Osmolarity Flashcards
If you drink a large amount of water what happens to osmolarity, volume, urine volume, and sodium excretion?
osmolarity - decrease
volume - increase
Uv - increase
ENa+ - decrease
If you drink a hypertonic saline solution what happens to osmolarity, volume, urine volume, and sodium excretion?
osmolarity - increase
volume - increase
Uv - increase
ENa+ - increase
If you get dehydrated (sweat, diarrhea) what happens to osmolarity, volume, urine volume, and sodium excretion?
osmolarity - increase
volume - decrease
Uv - decrease
ENa+ - increase
If you do not compensate from being dehydrated what happens to osmolarity, volume, urine volume, and sodium excretion?
osmolarity - decrease
volume - decrease
Uv - decrease
ENa+ - decrease
What controls both ECF osmolarity and plasma volume?
ADH
Decreased plasma volume causes an _______ in ADH
increase
Decreased osmolarity causes a _________ in ADH
decrease
Is ADH more sensitive to changes in volume or osmolarity?
osmolarity
What can cause syndrome of inappropriate ADH?
neurologic disease, head injury, lung tumors, or major surgery
What are the symptoms of syndrome of inappropriate ADH (SIADH)?
- excrete a concentrated urine
- too much ADH function
What does excessive secretion of ADH cause?
hyponatremia
decreased plasma osmolarity
urine hyperosmolarity
What is messed up with syndrome of inappropriate ADH (SIADH)?
- defect is in water excretion
- feedback inhibition of ADH does not occur
How do you treat syndrome of inappropriate ADH (SIADH)?
ADH inhibitor drugs (Demeclocycline)
What are the symptoms of diabetes insipidus (DI)?
- excrete diulte urine
- too little ADH function
- polyuria
- nocturia
- polydipsia
What are the three types of diabetes insipidus?
- hypothalamic or central (defect in ADH synthesis)
- nephrogenic (defect in ADH action)
- polydipsic (compulsive water drinking)
What are the three major mechanisms of polyuria?
– Decrease in Na+reabsorption (Kidney Disease, Diuretics)
– Reduced ADH secretion (D.I.)
– ADH resistance
What are the four mechanisms of Na+ regulation?
- Osmoreceptor-ADH
system. - The thirst mechanism
- Aldosterone and Ang II
➢ Alter Na+ mass but NOT conc
➢ Changes in Na+ mass accompanied by volume changes (thirst, ADH) - Salt Appetite
What increases the hypothalamic thirst center?
ECF hyperosmolarity
decreased ECF volume
decreased MAP
What hormone acts centrally to increase thirst?
angiotensin II
What stimuli increase salt appetite?
- sodium deficits
- decreased blood volume
- decreased blood pressure associated with circulatory insufficiency
