Acid-Base Balance Flashcards Preview

Pathohysiology > Acid-Base Balance > Flashcards

Flashcards in Acid-Base Balance Deck (72):
1

what is the normal systemic arterial blood pH?

7.4

2

what is considered a basic pH?

greater than 7.4

3

what is considered an acidic pH?

less than 7.4

4

Compensation

the attempt of renal and respiratory mechanisms to reestablish a normal pH

5

correction

the reestablishment of a normal systemic arterial blood pH, bicarbonate concentration, and carbonic acid concentration

6

what happens is pH is out of the normal range?

alterations in ion balance
alterations in membrane potentials
changes in the conformation of proteins (enzymes)

7

which pH range is not compatible with life?

less than 6.8 and greater than 7.8

8

Acidosis _______ the plasma concentration of calcium. Why?

increases
bc H+ displaces Ca from protein which increases blood Ca

9

what are the effects of acidosis?

depression of the CNS
coma and death

10

alkalosis _____ the plasma concentration of Ca.

decreases

11

what are the effects of alkalosis?

hyper-excitability of the CNS
convulsions and death

12

what are some extracellular buffers?

Bicarbonate
ammonia

13

what are some intracellular buffers?

protein
phosphate

14

What would happen with an increase in CO2?

the production of H+ would increase

15

what is the main driver of respiration?

the need to exhale carbon dioxide

16

what is a respiratory mechanism for adjusting body pH?

changing rate and depth of breathing

17

what are the 5 renal/metabolic mechanisms?

1-secretion of hydrogen into the urine and the recovery of bicarbonate from the urine
2-creation of new bicarbonate from the kidney by secretion of H+
3-buffering of secreted H+ by phosphate
4-creating bicarbonate by producing ammonium
5-buffering of H+ by ammonia

18

explain active secretion of H+ into the urine and recovery of bicarbonate from the urine

the net result of a hydrogen being secreted into the urine is a bicarbonate being recovered from the urine.

19

how much bicarbonate is usually recovered from the kidneys?

over 90%

20

explain the creation of new bicarbonate by primary active secretion of H+

hydrogen is secreted into the urine which increases the H+ concentration which then decreases pH. Because ATP is present, it allows H+ to go against its gradient (keep getting pumped out even though it's concentration is high) new bicarbonate is synthesized rather than uptaken

21

what is the lowest urine pH?

4.5

22

describe the creation of new bicarbonate through buffering of secreted hydrogen by phosphate

hydrogen pumped into the urine combines with buffers in the urine. the NaHPO4- is converted into NaH2PO4. Bicarbonate can then be synthesized.

23

what does converting NaHPO4- to NaH2PO4 enable?

we are then able to trap more H+ in the urine and thus produce more bicarbonate

24

describe creation of new bicarbonate through direct production of ammonium

when arterial blood pH is low, glutamine is converted to ammonium and bicarbonate. the ammonium is transported into the urine which results in an ammonium increase in urine.

25

describe the production of new bicarbonate through the buffering of ammonia

this occurs in the collecting ducts. we have ATP mediated transport of H+ into the urine which allows it to combine with ammonia and then more can be pumped out. one new bicarbonate ion is synthesized as the result of pumping out one H+.

26

what is the source of intracellular H+?

anaerobic (non-mitochondrial) metabolism of glucose.
ATP hydrolysis (big source of H+)
excessive formation of ketones

27

what about the excessive formation of ketones?

it reduces pH
they are produces in the liver by converting acetyl-CoA to ketones which are acidic.
insulin inhibits ketogenesis

28

how do we correct changes in pH?

chemical buffering
respiratory compensation
renal compensation

29

chemical buffering

occurs almost instantly

30

what is important considering buffers are rapidly exhausted?

this requires the elimination of hydrogen ions to remain effective

31

respiratory compensation

the respiratory center in the brainstem responds rapidly t changes in CSF pH. So, a change in plasma pH or pCO2 results in change in ventilation within minutes.

32

renal compensation

the kidneys respond to acid base balance changes by altering the amount of bicarbonate reabsorbed and hydrogen ions excreted. but, this takes a while. It can take up to 2 days for bicarbonate concentration to reach a new equilibrium.

33

pCO2 of arterial blood is basic if

pCO2 is less than 35-45 mmHg

34

pCO2 of arterial blood is acidic if

pCO2 is greater than 35-45 mmHg

35

HCO3- of arterial blood is acidic if

HCO3- is lesst han 24-28 mM

36

HCO3- of arterial blood is basic if

greater than 24-28mM

37

the problem is respiratory if

pCO2 matches pH

38

the problem is Metabolic (renal) if

HCO3- matches pH

39

how do you know which system is compensating for a change?

you determine which if opposing pH

40

what happens during respiratory acidosis?

there is a carbonic acid accumulation
hypercapnia (pCO2 > 40 mmHg)

41

what conditions can induce respiratory acidosis?

depression of respiratory center-drugs of head trauma
paralysis or trauma of respiratory or chest muscles.
chronic pulmonary disease (emphysema)

42

what are the symptoms of respiratory acidosis?

change in awareness and muscle control
respiration rate is initially high although ventilation is low (shallow breathing)

43

what are some symptoms during early respiratory acidosis?

restlessness
apprehension

44

what are some symptoms during middle respiratory acidosis?

lethargy
muscle twitching tremors

45

what are some symptoms during severe respiratory acidosis?

coma
death

46

what happens when metabolic compensation kicks in during respiratory acidosis?

conservation of HCO3-
an increase in HCO3- synthesis
elimination of H+ in the urine

47

how do you treat respiratory acidosis?

ventilation and treat cause of condition
bicarbonate IV infusion if pH is less than 7

48

what happens during respiratory alkalosis?

there is a deficit of carbonic acid
hypocapnia (pCO2<35 mmHg)

49

what is the most common acid base imbalance?

respiratory alkalosis.
hypocapnia (pCO2<35 mmHg)

50

what are some conditions that can induce respiratory alkalosis?

O2 deficiency at high altitudes (low paO2)
fever
acute anxiety (hyperventilation)

51

what are some symptoms of respiratory alkalosis?

dizziness
confusion
tinglng of extremities
coma (late)

52

How do we compensate for respiratory alkalosis?

excrete HCO3-
reduce HCO3- synthesis
conserve H+

53

how do we treat respiratory alkalosis?

treat cause of condition
have the patient re-breathe respiratory gases

54

metabolic acidosis

bicarbonate deficit
HCO3- < 24mM

55

what are some conditions that can induce metabolic acidosis?

diabetic ketoacidosis (kidneys likely suffering)
extreme prolonged exercise
renal failure
severe diarrhea

56

what are some symptoms of metabolic acidosis?

headache
lethargy
coma (late)
deep and rapid respiration
nausea
vomiting
diarrhea

57

what is respiratory and metabolic compensation for metabolic acidosis?

increase ventilation (to reduce pCO2-kussmaul breathing)
increase HCO3- recovery (if kidneys are functional)
increase HCO3- synthesis
increase H+ excretion

58

how do you treat metabolic acidosis?

treat cause of condition
if pH is less than 7, infuse with bicarbonate

59

disorders that cause you to hyperventilate could cause a

change in pH

60

Metabolic Alkalosis

bicarbonate excess
HCO3 >28 mM

61

what are conditions that can induce metabolic alkalosis?

loss of gastric juices due to vomiting or suction of stomach
excess bicarbonate ingestion or infusion

62

what are some symptoms of metabolic alkalosis?

weakness
muscle cramps
hyperactive reflexes
respiratory slow and shallow
confusion
convulsions

63

what is the respiratory and metabolic compensation for metabolic alkalosis?

reduce ventilation (increase pCO2)
decrease HCO3- recovery (if kidneys functional)
decrease HCO3- synthesis
decrease H+ excretion

64

how do you treat metabolic alkalosis?

treat cause of condition
if severe, HCl infusion

65

Respiratory failure that resulted in decrease delivery of oxygen to the tissues of the body and decreased removal of carbon dioxide from the body can result in

a combined metabolic and respiratory acidosis

66

normal

pH-7.4
pCO2-40
HCO3- 24

67

respiratory acidosis

ph-7.1 acidic
pco2- 80 acidic
bicab 24 normal

68

respiratory alkalosis

ph 7.5 basic
pco2 30 basic
bicarb 42 normal

69

metabolic acidosis

ph 7.2 acidic
pco2 40 normal
bicarb 20 acidic

70

metabolic alkalosis

ph 7.8 basic
pco2 40 normal
bicarb 60 basic

71

respiratory alkalosis with metabolic compensation

ph 7.5 basic
pco2 20 basic
bicarb 16 acidic

72

combines respiratory and metabolic acidosis

ph 7.2 acidic
pco2 48 acidic
bicarb 18 acidic