Acid/ Base Balance Flashcards
What is the normal pH of arterial blood?
7.4
What ion does the body produce?
H ions
Name 2 sources of H in the body?
Respiratory acids
Metabolic acids
An increase in acidic conditions will do what to ventilation?
Increase (breath off CO2)
What is a metabolic form of acid?
lactic acid
On a normal day, what is the net gain of H in the body?
50-100mmoles
What minimises changes in pH?
Buffers
What equation defines the pH in terms of ratio A/HA?
Henderson-Hasselbalch equation
pH = pK + log (A/HA)
pH §(HCO3)/pco2
What is the most important ECF buffer?
Bicarbonate
What is the ratio of bicarbonate to carbonic acid in the body?
20:1
What is the standard HCO level in the body?
24 mmoles (22-26)
What is the normal PCO?
40mmHg
If there is a reduction in H ions, what will happen to ventilation?
Reduce
How is H eliminated from the body?
From the kidneys
What is {HCO} regulated by?
Kidneys
What is PCO controlled by?
Lungs
What is exchanged for H moving into the cell? Why?
K ions
To maintain electrical neutrality
In acidosis, what can occur to the ECF?
Increase in K (hyperkalaemia)
How do the kidneys regulate HCO?
Reabsorb filtered HCO
Generate new HCO
What does the reabsorption & generation of new HCO depend on?
Active H secretion from tubule into lumen
In what form does HCO move across the cell membrane?
CO2
What is the name of the enzyme responsible for the conversion of CO > H2CO3?
Carbonic anhydrase
What passes into the peritubular kidneys?
Na & HCO3
Where does the bulk of HCO reabsorption occur?
Proximal tubule
How much HCO is filtered per day?
4320mmoles
How is H ions actively moved across the tubular membrane into the lumen?
Na/H antiporter
What is the minimum and maximum urine pH?
- 5
8. 0
What weak acids/ bases act as buffers?
uric acid
creatinine
dibasic phosphate
What is the importance of formation of titratable acidity?
Generates new HCO and excretes H
In titratable acidity, what molecule is responsible foe excreting H ions?
HPO4 (mono basic phosphate)
When HCO is reabosorbed, is H lost?
No excretion of H
Where does the process of titratable acidity occur? When?
Distal tubule
Acid overload
What is the major adaptive response to acid load?
Ammonium excretion
What does ammonium excretion generate?
Generates new HCO
Excretes H
When is ammonium excretion used?
Only for acid load
What are the properties of NH3+?
Lipid soluble
What does NH3+ combine with in the lumen?
H
Cl
What enzyme is responsible for the deamination of glutamine to form NH3?
Renal glutamine
What is the net outcome of ammonium excretion?
H secretion
Generation of new HCO
In the proximal tubule, the presence of which symporter allows NH4 to move into the lumen?
NH4/NA symporter
When ICF pH falls, what happens to renal glutamine activity?
Increases
How long does it take the kidneys to adapt to changes in pH?
4-5 days
A decrease in body pH is called??
Acidosis
An increase in body pH is called?
Alkalosis
Respiratory disorders affect what?
PCO2
Renal disorders affect what?
HCO
A reduction in ventilation would lead to CO2 retention and….
Respiratory Acidosis
Name a cause of acute respiratory acidosis
Drugs - opiates & barbituates
Name a change of chronic respiratory acidosis
Chronic bronchitis/ emphysema, asthma
When an increase in ventilation is observed and CO2 is blown off…… occurs.
Respiratory alkalosis
An acute cause of respiratory alkalosis is…
Voluntary hyperventilation
First ascent to altitude
A chronic cause of respiratory alkalosis is …..
Long term residence at altitude (inc ventilation due to < PO)
What are some of the causes of metabolic acidosis?
Diabetic ketoacidosis
Loss of HCO in diarrhoea
What is the name of a state of hyperventilation observed during diabetic ketoacidosis?
Kussmaul breathing
What are some of the causes of metabolic alkalosis?
Vomiting Aldosterone excess ( H loss)
A decrease in pH can be caused by either:
A decrease in HCO
Increase in PCO
An increase in pH can be caused by:
An increase in HCO
Decrease PCO
In acidosis, what happens to K levels?
Hyperkalaemia
What does insulin do to K ?
Stimulates cellular uptake
In hypovolaemia, aldosterone is secreted and acts on which tansporters at the lumen?
Na transporter (in)
H (out)
K (out)
What does excess ingestion of liquorice precipitate?
Metabolic alkalosis
What are cations?
Na & K
What are anions?
Cl & HCO
The following blood gas values were seen in a patient. Which simple Acid/Base Disturbance has he got?
pH = 7.32, [HCO-3]= 15 mM, PCO2 = 30mmHg (4kPa)
Metabolic acidosis
The following blood gas values were seen in a patient. Which simple Acid/Base Disturbance has he got?
pH = 7.32, [HCO-3]= 33 mM, PCO2 = 60mmHg (8kPa)
Chronic respiratory Acidosis
The following blood gas values were seen in a patient. Which simple Acid/Base Disturbance has he got?
pH = 7.45, [HCO-3] = 42 mM, PCO2 = 50mmHg (6.7kPa)
Metabolic Alkalosis
The following blood gas values were seen in a patient. Which simple Acid/Base Disturbance has he got?
pH = 7.45, [HCO-3]= 21 mM, PCO2 = 30mmHg (4kPa)
Respiratory Alkalosis (acute)
