Acid Base Physiology Flashcards
The lower the H concentration, the _____ the pH.
higher
Define strong acid/base.
a compound is a strong acid or strong base if it completely dissociates when placed into water
When does pKa=pH?
when half of the weak acid is in the non-dissociated form and half is in the dissociated form
Define weak acid/base.
a compound is a weak acid or weak base if it does not disassociate entirely when placed into water
What can weak acids or bases act as when acids or bases are introduced?
buffers to slow the change in pH when acids or bases are introduced
What is the law of electroneutrality?
in any solution the number of positive charges must equal the number of negative charges
If SID is positive, what must be increased to electrically offset it?
OH must increase in water
If SID is negative, what must be increased to electrically offset it?
H must increase in water
What are the major buffers of blood?
bicarbonate, plasma proteins, hemoglobin, and phosphate
What is the goal for H concentration to stay?
it must stay at 40 nM/L
What controls blood charge or SID?
strong ions, pCO2/HCO3, and other anions in the blood (protein)
What are the major strong ions in blood?
Na, Cl, K, Ca, and PO4
What ‘other’ anions affect blood charge?
albumin and hemoglobin
What is the normal arterial pH?
7.4
If the net charge of blood is positive, what is it considered?
alkaline
If the net charge of blood is negative, what is it considered?
acidic
If net charge is less than +2.5x10^-7, what will there be?
physiologic acidosis
If net charge is less than +2.5x10^-7, what will the pH be?
below 7.4 but above 7
If net charge is greater than +2.5x10^-7, what will there be?
physiologic alkalosis
If net charge is greater than +2.5x10^-7, what will the pH be?
above 7.4
How do the lungs contribute to plasma composition?
through ventilation and perfusion they provide CO2
How do the tissues contribute to plasma composition?
through perfusion, metabolism, and transport, they provide CO2 and strong ions to plasma
How does the gut contribute to plasma composition?
through absorption and secretion they provide strong ions to plasma
How does the kidney contribute to plasma composition?
through filtration, reabsorption, and secretion they provide strong ions to plasma
How does the liver contribute to plasma composition?
through synthesis and degradation it provides protein to plasma
What is the normal pCO2 level in arterial blood?
40 mmHg
What is the normal HCO3 level in arterial blood?
24 mEq/L
If pH is less than 7.35 what is that considered?
clinical acidosis
If pH is greater than 7.45 what is that considered?
clinical alkalosis
What is the normal pH of venous blood?
7.36
What is the normal pCO2 level in venous blood?
46 mmHg
What is the normal HCO3 level in venous blood?
27 mEg/L
What is the first thing to rule out when determining the cause of acidosis?
a respiratory cause
How do you know if acidosis is due to a respiratory cause?
if pCO2 is greater than 45 mmHg or HCO3 is greater than 28 mEq/L
If it is not respiratory acidosis, then what must it be?
metabolic acidosis
What could metabolic acidosis be due to?
a more negative than normal SID or a higher concentration of negatively charged plasma proteins or hemoglobin in the blood than normal
What anions can cause SID to be too negative?
not enough Na, Ca, or Mg or too much Cl, lactate, urate, HPO4, or NEFA
If SID is not the cause of the metabolic acidosis, what is?
most likely a high concentration of albumin, immunoglobulin, or a high packed cell volume or hemoglobin
What are the physiologic causes of too low SID?
diarrhea, renal failure, diabetes/ketosis, rhabdomyolysis, toxins, excess anions in the diet, poor tissue perfusion
How can diarrhea cause too low SID?
the gut fails to absorb secreted Na
How can renal failure cause too low SID?
Na is not reabsorbed and PO4 is not being secreted
How can diabetes/ketosis cause too low SID?
it leads to a build up of ketones and NEFA
How can rhabdomyolysis cause too low SID?
phosphate, sulfate, uric acid, and lactic acid is released from damaged muscle into the blood stream
How can poor tissue perfusion cause too low SID?
it can lead to a build-up of lactate
What is the first thing to rule out when determining the cause of alkalosis?
a respiratory cause
How do you know if alkalosis is due to a respiratory cause?
if pCO2 is less than 35 mmHg or HCO3 is less than 21 mEq/L
If it is not respiratory alkalosis, then what is it?
metabolic alkalosis
What could metabolic alkalosis be due to?
too positive SID or a low concentration of negatively charged proteins
What anions can cause SID to be too positive?
too much Na, Ca, Mg, and K or excessive Cl loss
What would cause too low levels of negatively charged blood proteins?
albumin, immunoglobulin too low, or PCV/hemoglobin too low
What physiologic causes can cause SID to be too positive?
vomiting, hyperaldosteronism, thiazide diuretics, excess diet cations
How can vomiting cause SID to be too positive?
loss of stomach Cl from the body
How can hyperaldosteronism cause SID to be too positive?
it causes increased retention of Na
How can thiazide diuretics cause SID to be too positive?
they block Na-Cl co-transport which leads to a net loss of Cl
What physiologic causes can cause HA to be too low?
liver failure, hypogammaglobulinemia, anemia, or excessive administration of saline IV
If an animal is experiencing acidosis, how does K act?
intracellular K is dumped into the blood causing hyperkalemia to be seen in the animal but the acidosis is compensated for
If an animal is experiencing alkalosis, how does K act?
K is reabsorbed from the blood to lower the pH which causes hypokalemia but the alkalosis is compensated for
If a patient has respiratory acidosis, how does the body compensate?
the kidneys secrete more Cl and the tubular reabsorption of Na and K increase
What will the urine be pH-wise if a patient is compensating for respiratory acidosis?
acidic
If a patient has metablic acidosis from diarrhea, how does it respiratorily compensate?
increased respiration to lower pCO2 and HCO3 to make the blood charge more positive
If a patient has metablic acidosis from diarrhea, how does it metabolically compensate?
the kidneys secrete more Cl and reabsorption of Na and K improves leading to more positive charges in the blood
If a pateint has respiratory alkalosis, how does the body metabolically compensate for it?
kidneys secrete less Cl and reabsorption of Na and K decreases leading to more negative charges in the blood
When compensating for respiratory alkalosis, what will the urine be pH-wise?
alkaline
How is the anion gap calculated?
([Na]+[K]) - ([Cl]+[HCO3])
What is the normal anion gap?
8-16 mM/l
What does an anion gap below normal suggest?
acidosis
What does an anion gap above normal suggest?
alkalosis
