acid base balance and cardiology GRADE 2

Question 1

signs and symptoms of hyponatremia

Answer 1

hx of fluid loss (ds & vs, exercise, heat stoke etc)
sx of hypovolemia
abdo cramps
cerebral oedema (due to swelling of cells)
muscle tremors, twitches and weakness
seizures, coma

Question 2

causes of hyponatremia

Answer 2

vomiting/diahorrea (excessive fluid/sodium loss)
excessive sweating (fluid loss)
Burns (fluid loss)
renal failure (dilution of fluid from urine retention)
diuretic use (fluid/sodium loss)
CCF (fluid retention)
increased ADH secretion (water retention)

Question 3

causes of hypernatremia

Answer 3

excessive water loss
extensive burns (fluid shift/loss)
severe watery stools (fluid loss)
diabetes insipidus 
salt water aspiration (increased sodium)
diabetic coma

Question 4

signs and symptoms of hypernatremia

Answer 4

restlessness, agitation, lethargy (CNS cells affected)
nausea/vomiting
intense thirst (ADH secretion due to low osmotic pressure)
twitching/ataxia (CNS calls affected)

Question 5

signs and symptoms of hyperkalemia

Answer 5

muscle weakness/irritability
nausea, abdo cramps, diarrhoea
low pulse, low BP (due to low cardiac output)
peaked T wave (to many K+ ions during repolarisation
arrhythmias
cardiac arrest

Question 6

osmotic diuresis

Answer 6

increased urine output due to presence of substances eg glucose within kidneys
substances cause increase in osmotic potential due to increased osmolarity
H2O and electrolytes drawn into intravascular space (lumen of kidneys)
all substances then excreted, body looses large amounts of fluid and electrolyes

Question 7

resting membrane potential

Answer 7

period that a cell remains at until it is stimulated by electronic stimulus (usually another cell)
some cells undergo “spontaneous depolarisation” AKA cardiac muscle automicity

Question 8

depolarisation

Answer 8

depolarisation (contracting) occurs once cell is stimulated
arrival of stimulus = sudden voltage charge on cell surface
this opens sodium channels and allows sodium influx to cell

Question 9

early rapid depolarisation

Answer 9

brief phase when sodium channels close and partial repolarisation occurs due to outward movement of K+ (reduces voltage)

Question 10

plateau phase

Answer 10

slow but continued movement of Ca+ into cell and K+ out (ST segment)

Question 11

Repolarisation

Answer 11

Ca+ and K+ move out of cell (decreasing voltage)
represented by T wave
hypokalemia = not enough voltage = dep T wave
hyperkalemia = too much voltage = peaked T wave

Question 12

5 phases of action potential

Answer 12

resting membrane potential
depolarisation
early rapid depolarisation
plateau phase
repolarisation

Question 13

what does P wave represent

Answer 13

atrial depolarisation

Question 14

what does QRS represent

Answer 14

ventricular depolarisation

Question 15

what does ST segment represent

Answer 15

early phase replolarisation of L/R ventricles

Question 16

what does the T wave represent

Answer 16

repolarisation of the ventricles

Question 17

what is the Q-T interval does and what does it represent

Answer 17

time from start of the QRS to end of the T wave

represents total duration of electrical conduction of ventricles

Question 18

what is a 1st degree AV block

Answer 18

disturbance caused by delay in conduction between AV node and ventricular depolarising cells
PR interval > 0.20 sec

Question 19

what is a 2nd degree type 1 AV block

Answer 19

intermittent block
conduction delay from AV to ventricles increases until conduction is blocked
seen as progressive increasing PR interval until nil QRS seen
P on the run = type 1

Question 20

what is a 2nd degree type 2 av block

Answer 20

atrial impulses are not conducted to ventricles
consecutive p waves (nil change in PR) until QRS dropped
P with no Q = type 2

Question 21

3rd degree heart block (complete)

Answer 21

Complete block below AV node
SA paces atria, ectopic paces ventricles
P wave and QRS both regular but nil relation exists