(IEMR9)Water and Electrolytes Flashcards
What is the TBW for males percentage?
60%
What is the TBW for women percentage?
50%
What is the equation for TBW?
ICF + ECF
ICF is what percentage of TBW?
2/3rd
ECF is what percentage of TBW?
1/3rd
Interstitial fluid volume is what percentage of ICF?
0%
Vascular fluid volume is what percentage of ICF?
0%
Interstitial fluid volume is what percentage of ECF?
2/3rd
Vascular fluid volume is what percentage of ECF?
1/3rd
If you provide a patient with 3 L of saline, what is the volume distribution?
1L to the ECF and 2 L to the ICF. .333 L will go to the vascular volume and .666 L will go to the interstitial volume.
If a person lost 1L of blood, how many L of normal saline are you going to provide to that patient?
9L of normal saline
What is the equation to calculate normal plasma osmolality?
Plasma osmolality = 2*[Na] + [Glucose]/18 + [BUN]/2.8
What is the normal concentration of BUN?
8-20 mg/dL
If a person has a dramatic increase in plasma glucose, you should be thinking what as a good differential diagnosis?
diabetes mellitus
If a person has a dramatic increase in BUN, you should be thinking what as a good differential diagnosis?
kidney failure
What is the equation for total body osmolality?
ECF osmolality + ICF osmolality
What is the equation for ECF osmoles?
ECF osmolality*ECF volume
What is the equation for ICF osmoles?
ICF osmolality*ICF volume
What are the main hormones for salt and water regulation?(3 points)
ADH, aldosterone and natriuretic hormones
ADH has a high affinity for what type of receptor in the kidneys?
V2
ADH has a low affinity for what receptor in the body
V1
What is the purpose of the V3 and V4 receptors?
ADH modifies drinking behavior by interacting with the V3 and V4 receptors in the pituitary and the hypothalamus, respectively speaking
Where is ADH synthesized?
It is synthesized in the supraoptic nuclei of the hypothalamus
What type of hormone is ADH?
peptide hormone
What assist the transfer of ADH to the posterior pituitary gland?
neurophysins
Main hormone involved in regulation of water balance and only hormone that increase reabsorption of solute-free water int he kidney collecting duct - by increase AQP-2 channels
ADH
What are the effects of ADH besides reabsorption of water in the collecting duct?(5)
secondarily increase the reabsorption of NaCl in the thick ascending limb, acts on V1 receptors on vasculature causing vasoconstriction in larger doses, stimulates ACTH secretion by acting on V3 receptors in the pituitary, has an affect on memory and cognition and stimulates gluconeogenesis
How does ADH affect urine osmolality?
It increases urine osmolality
How does ADH affect urine flow rate?
it decreases flow rate
How is ADH secretion regulated?(2 points)
Tonically inhibited by normal arterial pressure and the primary regulator is the normal osmolality state
What are potent stimulator of ADH secretion?(2 points)
nausea and vomiting
What are examples of physiological changes that decrease ADH/VP secretion?(5 points)
decreased plasma osmolality, increased inhibition due to increase firing of low volume receptors(by increasing the ECF volume), cold, drugs and glucocorticoids
What are examples of drugs that affect ADH secretion?(3 points)
alcohol, α-adrenergic agonist, opiate antagonist
How is ADH secretion affected during pregnancy?
How does ADH release change during trauma?
What happens if there is a deficiency of ADH?
diabetes insipidus: nephrogenic of hypothalmic
What are the types of diabetes insipidus?
nephrogenic or hypothalmic
What is SIADH?
excess release of ADH
SIADH usually leads to what?(3 points)
hyponatremia, water retention and significant increase in urine osmolality