15. Mass Action Acid Base & DSA: Acid-Base Physiology

Question 1

what is an acid

Answer 1

substance that donates H+

Question 2

what is a base

Answer 2

substance that accept H+

Question 3

What is a strong acid

Answer 3

(almost) completely dissociate into H+ and conjugate base in dilute aqueous sol’n

Question 4

What is normal range of P_aO2

Answer 4

80-100 mm Hg (age dependent)

Question 5

What is normal range of P_aCO₂

Answer 5

35-45 mm Hg

use 40 in class

Question 6

what is the normal range for pH_a

Answer 6

7.35-7.45

use 7.4o in class

Question 7

what is the normal range for HCO₃-

Answer 7

22-26 mEq/L

use 24 in class

Question 8

define acidosis or alkalosis

Answer 8

acidosis - < 7.35

alkalosis - >7.45

Question 9

changes in HCO_{3- =}

Answer 9

metabolic disturbances

(increase HCO3- = increase pH, vice versa)

Question 10

increased CO₂ leads to –>

Answer 10

acidosis

(decreased pH)

Question 11

what causes respiratory disturbances

Answer 11

alter CO₂

Question 12

how do you differentiate if the disturbance is metabolic or respiratory

Answer 12

changes in CO₂ = lungs - respiratory

changes in HCO_3- = kidneys - metabolic

Question 13

when do you get respiratory compensation

Answer 13

when kidneys are out of whack

• will try to fix pH by increasing/decreasing CO₂

Question 14

what is mass action

Answer 14

when one component is altered the other will too because changes/compensation

Question 15

what are the two rules for compensations

Answer 15

compensation will never get levels exactly back to normal

compensation made by other system

Question 16

how do you compensate if you are experiencing metabolic acidosis

Answer 16

increase ventilation to blow off CO2

if compensation is adequate –> expected PaCO2 = ((1.5*HCO3-) + 8) plus/minus 2

Question 17

how do you compensate metabolic alkalosis

Answer 17

decrease ventilation to retain CO2

Question 18

how do you calculate anion gap

Answer 18

= Na - (Cl- + HCO3-)

normal = less than or equal to 12

Question 19

Rule #1: positive and negative should ALWAYS balance themselves out

—how is the rule broken?

Answer 19

if you make an acid thats not measured in the test -

acid is consumed by HCO3- (bc acts like buffer)

Question 20

an elevated anion gap means there are—

Answer 20

unmeasured chemicals present

MUDPILES: _M_ethanol, _U_remia, _D_iabetic ketoacidosis/starvation/alc ketoacidosis, _P_araldehyde, _I_soniazid/iron, _L_actic acidosis, _E_thylene glycol/ethanol, _S_alicylates (aspirin)

Question 21

what is the equation for Osm

Answer 21

= (2*Na) + (glu/18) + (BUN/2.8)

normal around 290 mOsm/L