Physiology acid base balance

Question 1

what is the normal plamsa pH

Answer 1

7.4 (7.35-7.45)

Question 2

what can hydrogen ions combine with to reduce plasma pH

Answer 2

bicarb

Question 3

what regulates plasma conc of bicarb

Answer 3

kidneys

Question 4

what are the types of acid base disturbances

Answer 4

resp acidosis and alkanosis

metabolic acidosis and alkanosis

Question 5

what provides the immediate buffering for a pH change

Answer 5

immediate dilution of the acid/ base in ECF

blood buffers (Hb, HCO3-)
buffers in the ECF (particularly HCO3-)

Question 6

do immediate buffers have prolonged effect

Answer 6

no- get depleted quickly and have to be replaced by the kidney

Question 7

how does Hb work as a buffer

Answer 7

deoxygenated blood has a greater affinity for H+ so helps reduce acid in the blood

Question 8

what does an resp acidosis do to blood HCO3- levels

Answer 8

increases as more free H+ and acting as a buffer, being formed in response to the acid

(rise in H+ more tho)

Question 9

what diagram shows pH blood gas

Answer 9

davenport diagram

Question 10

what causes respiratory acidosis

Answer 10

= retention of CO2 as a result of: 
chronic bronchitis 
chronic emphysema 
airway restriction (bronchial asthma, tumour)
chest injuries 
resp distress (morphine/ GA)

Question 11

what does CO2 retention cause

Answer 11

the formation of carbonic acid which dissociates into free H+= acidosis

Question 12

what are bicarb levels like in a resp acisosis

Answer 12

high

Question 13

what is the compensation method for resp acidosis

Answer 13

no ECF buffering for this
(as resp system cause renal must compensate)
blood PCO2 drives H+ secretion by the kidney= CO2 stimulates H+ secretion into the filtrate (creates titratable acid and NH4+ in the urine)
reabsorbtion of all secreted bicarb ions

Question 14

what rises in resp acidosis compensation

Answer 14

HCO3-

Question 15

what is required for resp acidosis correction

Answer 15

restoration of normal ventilation

Question 16

what is compensation

Answer 16

restoring normal pH irrespective of HCO3- and PCO2 concentrations

Question 17

what is correction

Answer 17

restoration of pH and concentrations of HCO3- and PCO2 to within normal ranges

Question 18

what causes a respiratory alkalosis

Answer 18

= excessive removal of CO2 by the body:

low inspired Po2 @ altitude (hypoxia stimulates hyperventilation)
hyperventilation (fever, brainstem damage)
hysterical breathing

Question 19

what does excessive CO2 loss in resp alkanosis cause

Answer 19

both H+ and HCO3- fall

fall in H+ is what makes it an alkanosis- pH only measures free pH

Question 20

what is pH a measure of

Answer 20

free H+ ONLY

Question 21

what is HCO3- like in resp alkanosis

Answer 21

low (both H+ and HCO3- fall in resp to low CO2)

Question 22

what is the compensation for a resp alkanosis

Answer 22

(resp causes so renal compensates)
blood PCO2 drives H+ secretion- excessive removal of CO2 reduces H+ secretion into the tubule
HCO3- is excreted and urine is alkaline
no titrabable acid or NH4+ are formed so ‘new’ HCO3- is generated

Question 23

what does correction of resp alkanosis require

Answer 23

restoration of normal ventilation

Question 24

what causes a metabolic acidosis

Answer 24

= excess H+ from any source other than CO2:
-ingestion of acids or acid producing foodstuffs
-excessive metabolic production of H+ (lactic acid or ketoacidosis)
excessive loss of base from the body (diarrhoea- loss of HCO3-)

Question 25

what happens to HCO3- in metabolic acidosis

Answer 25

depleted as a result of buffering or lost from the body (diarrhoea)

Question 26

what is HCO3- like in a metabolic acidosis

Answer 26

LOW

Question 27

what is the compensation for metabolic acidosis

Answer 27

(resp not cause so can help compensation) decrease in plasma pH stimulates peripheral chemoreceptors- ventilation is quickly increased blowing off more CO2 (lowering H+ AND HCO3-) renal: H+ is lowered via secretion- titratable acid and NH4+ filitered HCO3- is reabsorbed HCO3- IS LOWERED

Question 28

why is resp compensation of metabolic acidosis essential

Answer 28

as acid load cannot be excreted immediately so need help from resp quickly

Question 29

what happens to HCO3- conc in compensation of metabolic acidosis

Answer 29

IS LOWERED

Question 30

what causes metabolic alkanosis

Answer 30

excessive loss of H+ from the body: - loss of HCL from the stomach (vomiting) - ingestion of alkali or alkali producing foods) - aldosterone hypersecretion (stimulates Na+/H+ exchange at the tubule = acid secretion)

Question 31

what happens to HCO3- in metabolic alkanosis

Answer 31

as a result of loss of H+ or addition of base HCO3 rises

Question 32

what is HCO3- like in metabolic alkanosis

Answer 32

high

Question 33

what is the compensation for metabolic alkanosis

Answer 33

increased pH slows ventilation (perpheral chemoreceptors) CO2 retained, PCO2 rises H+ rises lowering pH HCO3- also rises further

Question 34

what happens to HCO3- in resp compensation of metabolic alkanosis

Answer 34

rises

Question 35

what is the correction for metabolic alkanosis

Answer 35

filtered HCO3- load is so large compared to normal so not all can be reabsorbed no TA or NH4- produced HCO3- is excreted HCO3- falls back towards normal

Question 36

how long does renal excretion of H+ in resp acidosis take

Answer 36

hours to days- why you need restoration of normal ventilation

Question 37

what type of acidosis can undergo immediate ECF bufferning by HCO3-

Answer 37

non CO2 (metabolic)

Question 38

how long do the compensation mechanisms take for metabolic acidosis

Answer 38

resp comp- minutes intracellular buffering 2-4 hours renal excretion of H+ (days- weeks)

Question 39

What is ROME

Answer 39

resp opposite metabolic equal resp opposite: - acidosis= low pH= low CO2 (high HCO3) - alkalosis= high pH= high CO2 (low HCO3) metabolic equal: - acidosis= low pH= low HCO3 - alkalosis= high pH= high HCO3

Question 40

is potassium low in alkalosis or acidosis

Answer 40

alkaLOsis