Electrolytes Flashcards
What are the two types of electrolytes?
Anions
Cations
What direction does an anion move?
It has a negative charge and will move towards the anion
What direction does a cation move?
It has a positive charge and will move toward the cathode
What electrolytes are involved in volume and osmotic regulation?
Na, Cl, K
What electrolytes are involved in myocardial rhythm and contractility?
K (!!!!!), Mg, Ca
What electrolytes are involved as cofactors in enzyme activation?
Mg, Ca, Zn
What electrolytes are involved in blood coagulation?
Ca, Mg
___ to ___% of the human body weight is water
40-70%
Water is found in ____ intracellular and ___ of extracellular compartments
2/3 intra
1/3 extra
Define active transport
A mechanism that requires energy to move ions across the cellular membranes
Define diffusion
the passive movement of ions across a membrane. Dependent on size and charge of the ion being transported
What is the clinical significance of osmolality
- parameter to which hypothalamus responds
- regulation of osmolality affects plasma sodium concentration
- regulation of sodium and water controls blood volume
The following four factors affect what?
1: atrial natriuretic peptide
2: volume receptors independent of osmolality stimulating the release of AVP
3: GFR increasing with volume expansion and decreasing with depletion
4: Increase plasma sodium increase urine sodium and therefore water excretion and vice versa
Blood volume!
What is formula for OSMOLALITY
2(Na) + (glucose/20) + (BUN/3)
How do you calculate the OSMOLAL GAP
Difference between the calculated and determined osmolality (5-10 mOsm/kg)
(measured - calculated) the difference should be less than 5-10 units difference
___ us the most abundant cation in the ECF at ___%
Na
90%
Function of Na
active transport system
Reference range of Na
135-145 mmol/L
Which electrolyte is a major IC cation with a concentration 20 greater inside cells than outside?
K
Functions of K
regulation of neuromuscular excitability
contraction of heart
ICF volume
H+ concentration
Reference range for potassium in
Serum:
Urine:
Serum: 3.5-5.1 mmol/L
Urine: 33-86 mmol/d
What is a major extracellular anion that maintains osmolality, blood volume, and electric neutrality?
Cl
Reference range for Cl in the plasma/serum and urine (24 hr)
Plasma/serum = 98 -107 mmol/L
Urine (24hr) = 110 - 250 mmol/d (varies with diet)
What is bicarbonate?
The second most abundant anion in the ECF that is a major component of buffering system in blood
What makes up total Co2?
Bicarbonate: HCO3 (80%)
Carbonic Acid: H2CO3
Dissolved CO2
The fourth most abundant cation in the body, and second IC, is ____
Mg (1mole (24 g) in the body)
What electrolyte is essential for myocardial contraction?
Ca
Calcium is regulated by what three hormones?
PTH, Vit D, Calcitonin
How is Ca distributed in the body?
99% bone
1% in blood and other ECF
45% free circulation as calcium ion
Where is PO4 located?
Everywhere in living cells as it participates in key biochemical processes
What is the clinical significance of lactate?
It is by-product of when ATP is produced when oxygen is severely diminished. It accumulates in instances where we see cell death, so it is used to monitor critically ill patients
What is the anion gap
The difference between unmeasured anions and unmeasured cations
(Na + K) - (Cl - HCO3)
How is the anion gap created
by the concentration difference between commonly measured cations (Na and K) and anions (Cl and HCO3)
What causes an anion gap
Uremia/renal failure
ketpacidosis
lactic acidosis
hypernatremia
Reference range for anion gap
10-20 mmol/L
Describe how the electrolytes are reabsorbed in the renal tubules
Phosphate: reabsorption inhibited by PTH
Calcium: reabsorbed under influence of PTH
Magnesium: reabsorption occurs in Henle’s loop
Sodium: reabsorbed through three mechanisms
Chloride: reabsorbed by passive transport in proximal tubule
Potassium: reabsorbed by two mechanisms
Bicarbonate: recovered from glomerular filtrate
What is hypovolemia
Low blood volume/pressure
What is hypervolemia
High blood volume/pressure
Diabetes Insipidus involves what organ and what happens?
The pituitary gland
There is insufficient AVP and so the body cannot properly balance its fluid levels. This results in increased urine and an increased thirst.