electrolytes

Question 1

define osmolality

Answer 1

physical property of solutoin based on concentration solutes per kilogram of solvent

Question 2

describe the clinical significance of osmolality

Answer 2

• the parameter to which hypothalamus response
• regulation of osmolality affects plasma sodium concentration
• regulation of sodium and water controls blood volume

Question 3

how does AVP affect osmolality

Answer 3

AVP increases water retention in kidney, lowering osmolality
- drinking water increases extracellular water -> dilutes out salutes -> decreases osmolality

Question 4

how is osmolality calculated

Answer 4

2(Na)+(glucose/20)+(BUN/3)

Question 5

define osmolal gap

Answer 5

difference between calculated and determined osmolality - should be less than 5-10

Question 6

describe sodium in the body

Answer 6

• most abundant cation (90% of cation [])
• higher concentration outside of cells
• regulated by sodium potassium pumps in response to osmol changes

Question 7

what is sodiums reference range

Answer 7

135-145 mmol/L

Question 8

describe the role of potassium in the body

Answer 8

• major intracellular cation (20 times greater w/in cell)
• regulated by kidney
• neuromuscular excitability
• heart contractions

Question 9

what is the reference range for potassium

Answer 9

3.5-5.1 mmol/L

Question 10

describe chlorides purpose in the body

Answer 10

• major extracellular anaion
• maintains osmolality, blood vol and electric neutrality
• RR: 98-107

Question 11

describe bicarb in the body (electrolyte version)

Answer 11

• second most abundant anion in ECF
• major part of buffering system in blood
• exchanged for chloride in cell excretion of CO2

Question 12

describe magnesium

Answer 12

• fourth most abundant
• mostly in bones/muscles
• free magnesium acts as cofactor and are physiologically active
• regulated by kidneys

Question 13

describe the importance of calcium

Answer 13

• essential for myocardial contraction
• found in blood and other ECF at 1% of total vol
• increased vols in response to: PTH, vitamin D
• decreased from: calcitonin

Question 14

how does PTH impact calcium levels

Answer 14

• in bone stimulates osteoclast activity to release calcium
• in kidney promotes reabsorption of calcium
• activates vitamin D to bolster effects in bone marrow

Question 15

what is the calcium reference range

Answer 15

2.24-2.53 mmol/L

Question 16

how can hypomagnesemia impact calcium levels

Answer 16

• inhibits secretion of PTH
• impairs PTH action
• causes vitamin D resistance

Question 17

describe lactate

Answer 17

• by product of emergency ATP production
• used in metabolic monitoring over ammonia

Question 18

define anion gap

Answer 18

the difference between unmeasured anions in solution and unmeasured cations

Question 19

what is anion gap useful for

Answer 19

indicating increase in one or more unmeasured anions in serum

Question 20

how is anion gap calculated and what is the reference range

Answer 20

• [Na+K]-[Cl+HCO3]
• 10-20 mmol/L

Question 21

how is chloride reabsorbed

Answer 21

passive transport in proximal tubule

Question 22

how does ANP (atrial natriuretic peptide) effect blood vol

Answer 22

released from heart in response to hypervolemia to increase salt and water excretion

Question 23

how are sodium and water linked in regards to blood volume

Answer 23

where sodium goes, water follows