Acid Base Balance Flashcards
what happens to the pH as H+ increases
it decreases
what is the normal arterial pH
7.40
what is the normal range of arterial pH
7.35-7.45
what is the normal HCO3-
24mM
what is the normal H2CO3
1.2mM
what is the ratio of HCO3 to H2CO3
20:1
pCO2 x solubility in water = what
moles of carbonic acid
what is the formula to determine moles of carbonic acid
pCO2 x solubility in water = moles
what produces bicarbonate in the body
kidney
what are the 2 ways the kidney produces bicarbonate
1) convert buffered acids into more acid salts
2) produce new HCO3-
glutamine becomes what
NH4 and HCO3-
a drop in the pH stimulates what in the lungs
ventilation to drop CO2
what is the metabolic component in acid base balances
HCO3-
what is the respiratory component in acid base balance
dissolved carbon dioxide
what is the normal range of plasma HCO3-
22-28mM
when does metabolic acidosis occur
under 22 mM of HCO3-
when does metabolic alkalosis occur
when plasma HCO3- is over 28 mM
name 3 reasons metabolic acidosis occurs
decreased HCO3- production (kidney)
loss of base
increase addition of fixed acid
what is the anion gap
difference between the measured cations and the measured anions in plasma
what is the formula for anion gap
(Na + K) - (Cl + HCO3-)
what is the normal anion gap
6-16 mmol/L
what is the anion gap used to determine
if metabolic acidosis is due to an accumulation of non-volatile acids OR a net loss of biocarbonate
what are some causes of a normal anion gap metabolic acidosis
gut bicarbonate loss
Renal bicarb loss
how does the body compensate for a renal bicarbonate loss
rise in plasma chloride (kidneys try to reabsorb more chlorine)
what is an increased anion gap metabolic acid
an addition of an acid that increase the anion gap
what are the 2 causes of increased anion gap metabolic acidosis
addition of acid
failure of acid secretion
at what level of GFR does the kidney struggle to excrete H+ and retain acid anions
under 20 mL/min
what is the normal pCO2 and the normal range
range - 35-45 mmHg
pCO2 - 40 mmHg
when does resp acidosis occur
PCO2 over 45 mm Hg
when does resp alkalosis occur
when PCO2 is under 35 mm HG
Pulmonary hypoventilation is a big cause of:
resp acidosis
what causes pulm hypoventilation
asthma
rib fractures
tumors
emphysema
edema
lots of things
what is pulm hyperventilation caused by
anxiety
salicylate ingestion
extreme pain
at what level of pH are seizures a risk
7.8
what is the normal range of plasma potassium
3.5-5 mM
plams (K) under 3.5mM is
hypokalemia
plasma (K) over 5 mM is
hyperkalemia
what does aldosterone do with regards to sodium
activates ENaC to bring Na into the cell
will aldosterone be secreted for high or low potassium levels
high
what has the greatest effect on membrane potential
changes in ECF potassium
what would you see on an ECG with hyperkalemia
widened QRS
peaked T wave
what would you see on an ECG with hypokalemia
flattened T wave
U wave appears
what is a big heart danger with hyperkalemia
cardiac arrest
what is a big heart danger with hypokalemia
fatal arrythmias
what effect does insulin have on potassium
stimulates uptake
what do catecholamines do with potassium
stimulate uptake
what releases catecholamines
sympathetic nerves
adrenal medulla
how do you treat hyperkalemia if K is over 6.5 and only has peaked T waves
decrease K intake
remove the cause
stop K-sparing diuretics
name 3 most serious electrical effects of hyperkalemia
sustained gradual depolarization
inactivation of Na channels
Renders the heart virtually unexcitable
name 3 ways to treat hyperkalemia if K is over 6.5 with an abnormal ECG or if K is over 8
antagonise electrical effects
redistribute K
Remove K from the body
name 3 of the most serious electrical effects of hypokalemia
sustained hyperpolarization causes full activation of Na channels
Conduction abnormalities
prolonged repolarization
what effect does sustained hyperpolarization have on QRS complex
it shortens it
what percent of sodium reabsorption is each part of the nephron responsible for
proximal - 65
ascending limb - 25
distal - 7
collecting duct - 3
what diuretic affects the ascending limb
loop
what diuretic affects the distal tubule
thiazides
what diuretic affects the collecting duct
amiloride
mutations in genes that code for what type of cell can cause bartters syndrome
sodium potassium chloride cotransporters
mutations in genes that inactivate sodium potassium chloride transporter cause what kind of syndrome
Bartters
Bartters syndrome affects what part of the nephron
ascending limb
gitelman’s syndrom affects what part of the nephron
distal tubule
Pseudohypoaldosteronism affects what part of the neprhon
collecting duct
Gitelman’s syndrome affects what cotransporter
Sodium chloride
pseudohypoaldosteronism affects what channel
ENaC
what ion builds up in the blood with pseudohypoaldosteronism
K
what is the normal sodium plasma
137-145 mmol/L
what happens to cells in a hypertonic ECF expansion
they shrink - water leaves cells to dilute the ECF
does volume of ECF in a hypotonic expansion inc or dec
increase
what does ADH do
acts on nephrons to stimulate water reabsorption
what is hyponatremia
too little sodium
what is the major solute in the ECF
sodium
what are some clinical features of hyponatremia
brain edema:
lethargy
confusion
agitation
seizures
what is hypovolemic hypernatremia due to
loss of water from the kidneys
what is isovolemic hypernatremia due to
diabetes insipidus
what is hypervolemic hypernatremia due to
renal retention de to hyperaldosteronism
what are some clinical features of hypernatremia
brain cells shrink due to water leaving:
muscle twitches and seizures
what is diabetes insipidus
a deficient in signaling to the aquaporin channels causing lack of water retention
what 2 things does PTH stimulate
Ca uptake in kidneys
Ca release from bones
what does active vitamin D stimulate
Ca uptake in intestines
as blood calcium levels go up, what happens to phosphate
it goes down
why does an increase in calcium lower phosphate levels
because it inhibits the release of PTH (which releases phosphate)
why does an increase in phosphate dec calcium levels
because phsophate binds to calcium reducing the amount of free calcium available
what are 2 main causes of hypercalcemia
hyperparathyroidism
malignancy
what are some treatments of hypercalcemia
loop diuretics
surgery to remove PT tissue if PTH is too high
what are some clinical features of hypercalcemia
lethargy
depression
kidney stones
nauseau
Shorter QT interval
name 3 causes of hypocalcemia
vit d deficiency
hypoparathyroidism
hyperphosphatemia
what are some clinical features of hypocalcemia
neuromuscular irritability
muscle cramps
prolonged QT interval
what is bone disease in CRF due to
loss of calcium phosphate from bone that cannot be replaced due to deficiency of active vit D
PTH (inc or dec) as GFR (inc or dec)
increases as GFR decreases
what is the trade off hypothesis
how PTH increases as GFR decreases
what are 3 treatments for bone disease in CKD
reduce phosphate intake
GI phsophate binders
inject active vit D
