Respiration Lecture 11: Resp. Acid-Base Balance Flashcards Preview

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Flashcards in Respiration Lecture 11: Resp. Acid-Base Balance Deck (62)
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0
Q

Base

A

ion or molecule that can accept a H+ atom. A- in HH equation

1
Q

Acid

A

molecules containing H+ atoms that can be released into solutions. HA in HH equation.

2
Q

When is buffer system most resistant to changes in H+?

A

When pH = pK

3
Q

Normal extracellular pH range

A

7.35-7.45

4
Q

3 main mechanisms to keep pH within normal limits

A

1) extracellular buffering (don’t actually remove H+ from system)
2) adjustments to blood PCO2 by altering the ventilatory capacity of the lungs (<—THE MAIN METHOD…KNOW!)
3) adjustments to renal acid excretion or base reabsorption

5
Q

Acidemia

A

acidic blood (high H+ conc.)

6
Q

Alkalemia

A

alkaline blood (low H+ conc.)

7
Q

where is H ion state measured?

A

receptors in CSF

8
Q

weak acid or base

A

acid or base that incompletely dissociates. (pK is such that it doesn’t completely dissociate)

9
Q

buffer

A

reduces changes in pH resulting from the addition of strong acids or bases

10
Q

What is greatest source of H+?

A

CO2 (via oxidation of glucose and fatty acids during metabolism)

11
Q

CO2 is an example of what type of acid?

A

volatile acid

12
Q

Non-volatile acids that are sources of H+ in metabolism

A

sulfuric, phosphoric, hydrochloric, and lactic acids

13
Q

The #1 blood buffer

A

Bicarbonate ***** Most important because the buffered H+ ion it can carry can be removed by both the renal and respiratory systems

14
Q

Other blood buffers besides bicarbonate

A

phosphate, proteins

15
Q

Henderson-Hasselbalch Equation

A

HA H+ + A- and pH = pKa + log [A-]/[HA] DNK

16
Q

how many pH units around pK can buffer act?

A

+/- 1 pH unit

17
Q

Buffer strength is directly proportional to ?

A

concentration of paired buffer components

18
Q

Non-bicarbonate buffer systems

A

Phosphate buffer system

Protein buffer system

19
Q

Bicarbonate buffer system **

A

utilizes carbonic anhydrase reaction to maintain blood pH. carbon dioxide (CO2) combines with water to form carbonic acid (H2CO3), which in turn rapidly dissociates to form hydrogen ions and bicarbonate (HCO3- ) as shown in the reactions below. The carbon dioxide - carbonic acid equilibrium is catalyzed by the enzyme carbonic anhydrase; the carbonic acid - bicarbonate equilibrium is simple proton dissociation/association and needs no catalyst. An OPEN SYSTEM via elimination of CO2 and H+ to the environment

20
Q

Carbonic anhydrase reaction

A

CO2 + H2O H2CO3 H+ + HCO3-

CO2 = acid (proton donor)
HCO3 = base (proton acceptor)
H+ = free proton responsible for setting pH
21
Q

If alveolar pressure decreases due to hypoventilation, what happens to pH?****

A

increase in PCO2, so pH decreases (increase in H+)

22
Q

Phosphate buffer system reaction

A

H2PO4 H+ + HPO4

23
Q

What happens to acidity of Hb as O2 leaves?

A

Decreases

24
Q

deoxyhemoglobin

A

Hb that is desaturated of O2

25
Q

Hb protein buffer system

A

Hb becomes more acidic when it binds O2, allowing less CO2 to be transferred as bicarbonate and vice versa.

26
Q

Which two organs regulate the bicarbonate buffer system?

A

lungs and kidneys

27
Q

Only way to ELIMINATE H+ ?

A

via blown off CO2 or renal excretion

28
Q

most important blood borne protein buffer

A

Hb

29
Q

protein with highest conc. in blood

A

Hb

30
Q

Is Hb classified as extracellular or intracellular?

A

extracellular

31
Q

Where is phosphate buffer system strongest and why?

A

kidney. Env. is more acidic and phosphate is higher

32
Q

How does bicarbonate buffer system compensate for its low pK?

A

By being an open system

33
Q

organ that releases the largest amount of acid

A

resp. system

34
Q

primary body systems that regulate H+

A

respiratory, renal, and gastrointestinal

35
Q

How does removal of CO2 also remove H+?

A

For every molecule of CO2 eliminated, an H+ is bound to H2O removing it from solution

36
Q

2nd most important buffer in the body

A

proteins (ex: Hb, myoglobin)

37
Q

Increasing V’A –> PaCO2?

A

decrease

38
Q

Respiratory acidemia

A

low pH due to change of breathing. A retention of CO2 generally caused by respiratory problems such as hypoventilation

39
Q

Respiratory alkalemia

A

high pH due to change of breathing. Excessive loss of CO2 generally caused by hyperventilation

40
Q

Metabolic acidemia

A

low pH due to change in body metabolism

41
Q

Metabolic alkalemia

A

high pH due to change in body metabolism

42
Q

How does bicarb. buffer system react to increased acid?

A

driving force to L. More CO2 will be released by lungs via increased ventilation (i.e. “ketone breathe”)

43
Q

How does bicarb. buffer system react to increased CO2?

A

driving force to R. More HCO3- removed by kidneys

44
Q

low pH, high PaCO2 indicates:

A

respiratory acidemia

45
Q

high pH, low PaCO2 indicates:

A

respiratory alkalemia

46
Q

low pH, low PaCO2 indicates:

A

metabolic acidemia

47
Q

high pH, high PaCO2 indicates:

A

metabolic alkalemia

48
Q

High PaCO2 –> HCO3- concentration?

A

also high.

49
Q

blood buffer line on Davenport diagram represents:

A

buffering capacity of blood

50
Q

4 types of acid-base disturbances

A

respiratory acidemia
respiratory alkalemia
metabolic acidemia
metabolic alkalemia

51
Q

How is respiratory acidemia compensated?

A

metabolically (i.e. kidney retain base HCO3-)

52
Q

How is respiratory alkalemia compensated?

A

metabolically (i.e. kidney loses net base HCO3-)

53
Q

FIRST priority in compensating for an acid-base disturbance

A

Restore pH

54
Q

possible causes of metabolic acidemia

A

diabetes, heart failure, renal failure, diarrhea. Addition/retention of non-volatile acid, or loss of base.

55
Q

possible causes of metabolic alkalosis

A

loss of non-volatile acid, intake of base. I.e. - vomiting

56
Q

Compensation for metabolic acidemia

A

respiratory compensation. Lungs excrete more CO2 via hyperventilation

57
Q

Compensation for metabolic alkalosis

A

respiratory compensation. Lungs excrete less CO2 via hypoventilation

58
Q

Review Davenport Diagram in notes

A

:)

59
Q

Possible causes of respiratory acidosis

A

insufficient ventilation, CNS depression, obesity, etc.

60
Q

Possible causes of respiratory alkalosis

A

CNS mediated hyperventilation, peripheral stimulation of ventilation, hypoxemia, pregnancy, etc.

61
Q

pH =

A

-log[H+]. Also, pH = constant + Kidneys/Lungs

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