Lecture 39 4/12/24

Question 1

What is pH?

Answer 1

the negative log of H+ conc.

Question 2

What is an acid?

Answer 2

substance that can donate H+

Question 3

What is a base?

Answer 3

substance that can accept H+

Question 4

What is a strong acid?

Answer 4

acid that gives up all H+ in solution

Question 5

What is a weak acid?

Answer 5

acid that only releases some H+ when in solution

Question 6

What is a buffer?

Answer 6

-chemical that helps minimize changes in pH in a solution
-typically occurs as a buffer pair, such as a weak acid and conjugate base

Question 7

What are the main contributors to acid-base homeostasis?

Answer 7

-buffers
-lungs
-kidneys

Question 8

What are the characteristics of how buffers work?

Answer 8

-work quickly to titrate excess H+
-more of a chemical reaction that a physiologic response

Question 9

What is the main buffer in the body?

Answer 9

HCO3- (bicarb.)

Question 10

What are the characteristics of carbonic anhydrase?

Answer 10

-produced by RBCs and renal tubular cells
-speeds up the Henderson-Hassalbalch equation in both directions

Question 11

What is the Henderson-Hassalbalch equation?

Answer 11

CO2 + H2O <-> H2CO3 <-> HCO3- + H+

Question 12

What are the characteristics of CO2?

Answer 12

-acts as a resp. acid
-delivered to the lungs, where it can be breathed out

Question 13

What do central chemoreceptors respond to?

Answer 13

CO2 and pH

Question 14

What do peripheral chemoreceptors respond to?

Answer 14

CO2, pH, and PaO2

Question 15

What is the ventilatory response to CO2?

Answer 15

ventilation increases dramatically once PaCO2 reaches a threshold level

Question 16

What are the characteristics of hypoventilation?

Answer 16

-retain CO2
-increased pCO2
-decreased blood pH

Question 17

What are the characteristics of hyperventilation?

Answer 17

-expire more CO2
-decreased pCO2
-increased blood pH

Question 18

What are the roles of the kidneys in acid base?

Answer 18

-acidify urine to eliminate acid from body and increase blood pH
-alkalinize urine to eliminate base from body and decrease blood pH

Question 19

What can the kidney do the acidify the urine in the proximal tubule?

Answer 19

-resorption of HCO3-
-regeneration of HCO3-
-excretion of H+ (major mechanism)

Question 20

What can the kidney do to acidify the urine in the alpha intercalating cells and collecting ducts?

Answer 20

-production of H+ (excreted) and HCO3- (resorbed) via carbonic anhydrase
-K+/H+ exchanger

Question 21

What can be done in the beta intercalated cells and collecting ducts to alkalinize the urine?

Answer 21

production of HCO3- (excreted) and H+ (resorbed) via carbonic anhydrase

Question 22

How does acidosis compare to alkalosis?

Answer 22

-acidosis is a process that promotes decrease in blood pH
-alkalosis is a process that promotes increase in blood pH

Question 23

How does resp. acid-base disorder differ from metabolic acid-base disorder?

Answer 23

-resp. involves change in blood pCO2
-metabolic involves change in blood HCO3- conc.

Question 24

What is respiratory acidosis?

Answer 24

increased pCO2

Question 25

What is respiratory alkalosis?

Answer 25

decreased pCO2

Question 26

What is metabolic acidosis?

Answer 26

decreased HCO3-

Question 27

What is metabolic alkalosis?

Answer 27

increased HCO3-

Question 28

What are the characteristics of resp. acidosis?

Answer 28

-hypoventilation -increased pCO2 -less CO2 expired by lungs -ex. are CNS disease, toxins

Question 29

What are the characteristics of resp. alkalosis?

Answer 29

-hyperventilation -decreased pCO2 -more CO2 expired by lungs -ex. is panting

Question 30

What are the two possible mechanisms of metabolic acidosis?

Answer 30

-accumulation of acids -loss of bicarbonate

Question 31

What are the results of metabolic acidosis?

Answer 31

-dec. HCO3- -dec. blood pH

Question 32

Which acids can accumulate in metabolic acidosis?

Answer 32

-glycol -oxoproline -L-lactate -D-lactate -methanol -aspirin -renal failure/uremia -ketoacidosis

Question 33

What can lead to a loss of bicarb. in metabolic acidosis?

Answer 33

-renal tubular dysfunction -diarrhea/GI losses

Question 34

What are the possible mechanisms of metabolic alkalosis?

Answer 34

-loss of acids -accumulation of bicarbonate

Question 35

What are the results of metabolic alkalosis?

Answer 35

-inc. HCO3- -inc. blood pH

Question 36

What can cause a loss of acids?

Answer 36

-refluxing -vomiting

Question 37

What is compensation?

Answer 37

-physiologic response to an acid-base disturbance -goal is to minimize blood pH change -typically involves lungs or kidneys

Question 38

How does compensation happen?

Answer 38

the primary problem is matched with its opposite; ex. is resp. acidosis and metabolic alkalosis

Question 39

What are the rules of compensation?

Answer 39

-pH will never return to normal range --goal is to get pH closer to normal --return of pH to normal indicates mixed disturbance -body will never overcompensate

Question 40

Which type of compensation occurs more quickly?

Answer 40

respiratory

Question 41

Why are compensatory responses not always evident?

Answer 41

-inadequate time -disease that impedes compensation

Question 42

How can acid-base be evaluated in bloodwork?

Answer 42

blood gas analysis: -pH -pCO2 -HCO3- chem panel: -HCO3- -Na and Cl -anion gap