Sodium and Water

Question 1

what are U&E’s

Answer 1

urea and electrolytes

such as Na, K, Cl, HCO3, urea and creatinine

Question 2

what are the basic subtypes of abnormal electrolyte disorders

Answer 2

can indicate primary state disease

secondary consequence of a multitude of diseases

Question 3

why, physiologically, are electrolytes important

Answer 3

maintenance of cellular homeostasis
implications on cardiovascular physiology
implications on renal physiology
electrophysiology (CNS, heart)

Question 4

what are some clinical examples of electrolyte disturbances

Answer 4

haemorrhage 
D&V 
poor intake 
increased losses
DI 
DM
diuretic therapy 
endocrine disorders (ADH, aldosterone)

Question 5

what are the 5 concepts of electrolyte balance

Answer 5

concentrations, compartments, contents, volumes rates of gain and loss

Question 6

what does the concentration of electrolytes depend on

Answer 6

water in and out

Question 7

what is the normal Na+ plasma conc

Answer 7

140 mmol/L

Question 8

what would happen to electrolyte conc in decreasing or increasing ECF/ICF fluid volume

Answer 8

decreasing ICF/ECF = increase conc of electrolyte in plasma

increasing ICF/ECF = decreased conc of electrolyte in plasma

Question 9

what happens when you lose isotonic fluid

Answer 9

nothing as conc roughly same as blood, no change in conc and no fluid redistribution
cell shrink

Question 10

what happens when you lose hypotonic solution

Answer 10

eg water and fluid of lower conc than blood
greater loss from ICF than ECF = increase in Na conc
cell shrink

Question 11

what happens when you gain isotonic fluid

Answer 11

no change in conc but an increase in BP

cell oedema

Question 12

what happens when you gain hypotonic fluid

Answer 12

greater gain to ICF than ECF
small decrease in Na
causes cell oedema

Question 13

what are the three physical compensatory mechanisms of alter electrolyte balance

Answer 13

thirst
ADH
RAS

Question 14

what is the role of ADH is electrolyte balance

Answer 14

produced by median eminence with increased water osmolality
decreases water loss and increase water retention
increases thirst

Question 15

how does the RAS aid electrolyte balance

Answer 15

renin - angiotensin - aldosterone
activated by reduced vascular volume, sodium depletion or haemorrhage
causes renal sodium retention

Question 16

what are two therapeutic techniques for electrolyte imbalance

Answer 16

IV therapy

diuretics

Question 17

what is hyponatraemia, hypernataemia, dehydration in terms of water and sodium

Answer 17

hypo - small Na in ECF with excess water
hyper - large Na in ECF with small water
Dehy - na and water depletion

Question 18

how is hyponatraemia caused by diuretics

Answer 18

decrease in urine Na re-absoprtion so more na released in urine which decreases GFR and increases plasma creat, urea and ADH

Question 19

how is hyponatraemia caused by SIADH

Answer 19

syndrome of inappropriate ADH

stops water loss so dilutes Na in your system

Question 20

describe how hypernatreamia is caused by decreased water intake

Answer 20

less water = more Na conc in blood, increase in urine osmolality and decrease in urine volume
increase in plasma creat and urea

Question 21

describe how hypernatraemia is caused by osmotic diuresis

Answer 21

increase in plasma glucose which increases renal loss - this increase haemoconcentraiton and increases plasma Na conc
also increases plasma creat and urea