9 Acid-Base Balance Flashcards Preview

3 Respiratory Unit > 9 Acid-Base Balance > Flashcards

Flashcards in 9 Acid-Base Balance Deck (34)
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1

Why is alkalaemia more dangerous than acidaemia?

Alkalaemia causes calcium ions to come out of solution and bind to other molecules

2

Why does alkalaemia increase neuronal excitability?

Lowers free calcium by causing Ca2+ ions to come out of solution

Also causes hypokalemia- more excitable state for neurons

3

What symptoms might someone get if their blood pH reach >7.45?

Parasthesia and tetany (intermittent muscular spasms)

4

Explain how acidaemia can cause arrhythmia. What other consequences can acidaemia have systemically?

  • Increase K+ concentration in plasma
    • Effects excitability of muscle (esp cardiac)
  • Denatures proteins
    • Affects glycolysis
    • Hepatic function

5

What is the normal concentration of hydrogen carbonate in the blood? Where is it made and where is it controlled?

6

Why is hydrogen carbonate concentration in plasma not depleted when we produce acid due to metabolism?

  1. Kidney's recover all filtered HCO3-
  2. HCO3- made: 
    1. PCT: from amino acids- put NH4+ into urine
    2. DCT: from COand H2O

7

How is hydrogen carbonate reabsorbed in the proximal convulted tubule?

  1. HCO3- in lumen of PCT
  2. Sodium- hydrogen exchanger- pumps hydrogen ions into lumen and sodium in
  3. H+ and HCO3-​ react to from H2O and CO2
  4. H2O and CO2 move into tubular cell
  5. Converted back into HCO3-​ - moves into ECF

8

How is HCO3- created from glutamine in the PCT?

(glutamine= an amino acid)

9

What happens to hydrogen ions and the hydrogen carbonate ions that are produced from the reaction of water and carbon dioxide in the distal tubules and collecting ducts?

Phosphate therefore used to create buffering system

10

Outline the role of ammonia in the control of pH.

pH drop- increase excretion of ammonia

ammonia buffers more hydrogen ions to form amonium- ammonium trapped

11

What is the minimum pH of urine? Why does the pH not go below this?

minimum pH: 4.5

doesn't fall below: Due to buffering system (ie phosphate and ammonia if no HCO3-)

12

Why does acidosis result in hyperkalaemia?

Reciprocal ion shift

13

What effect will hypokalaemia have on acid base balance?

Will cause metabolic alkalosis- H+ ions move into cells

 

14

What causes these blood levels: 

Hypoventilation

Hypercapnia

Respiratory acidosis

15

What causes these blood levels:

Hyperventilation 

Hypocapnia 

Respiratory alkalosis

16

What happens to [HCO3-] to compensate for:

Repiratory acidosis?

Respiratory alkalosis?

How long does this take (to return to normal)

 

17

What do these levels indicate?

Compensated respiratory acidosis

18

What do these levels indicate?

Compensated respiratory alkalosis

19

If there is a fall in [HCO3-] in the blood, this can lead to metabolic acidosis. Why will there not be an increase in arterial pCO2?

20

Which anions and cations are used to measure the anion gap?

21

What would cause the anion gap to increase?

If HCO3- is replaced by anions from other acids (eg lactic acid)

22

What condition is initially characterised by these values?

Metabolic acidosis

23

How is metabolic acidosis compensated for?

24

What condition is charaterised by these values?

Compensated metabolic acidosis

25

What condition is characterised by these values?

Metabolic alkalosis

26

Why can't metabolic alkalosis be completely compensated for by reducing breathing?

Need to maintain pOso can only reduce breathing by so much

27

What effect will type 2 respiratory failure have on pH? Give examples of what can cause type 2 respiratory failure.

Effect on pH: Low O2 and High CO2- RESPIRATORY ACIDOSIS

(compensated for by incrase HCO3-)- so pH near normal

Conditions causing:

  • Severe COPD
  • Severe asthma 
  • Drug overdose (supressed ventilation) 
  • Neuromuscular disease

 

 

28

What is type 1 respiratory failure?

 hypoxia without hypercapnia

Low pO2 and normal to low pCO2

eg. Hypervenitlation in response to long-term hypoxia

 

29

What is an ion gap increase indicative of? What can cause this?

Metabolic production of an acid

 

30

Give examples of conditions which can cause metabolic acidosis without affecting the anion gap (ie renal related and hydrogen carbonate replaced by chloride ions)