Integrated control of breathing Flashcards
What is blood pH proportional to?
The ratio of [HCO3-] to PaCO2,
What are disruptions in pH homeostasis caused by?
From respiratory (CO2) or metabolic (HCO3-) dysfunction (↓pH = acidosis, ↑pH = alkalosis).The cause of the pH disturbance can be determined by whether it is accompanied by changes in [HCO3-] or PaCO2.
What is a low pH and high PaCO2 called and why?
Respiratory acidosis, as hypoventilation is responsible for the increase in CO2 levels and decreased pH:
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What is a high pH and low PaCO2 called and why?
Respiratory alkalosis, as hyperventilation is responsible for the decrease in CO2 levels and increased pH:
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What is a low pH accompanied by low [HCO3-] called and why?
metabolic acidosis, as excessive metabolic acid production and/or increased excretion of HCO3- is responsible for the decreased pH:
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What is a high pH accompanied by high [HCO3-] called and why?
Metabolic alkalosis, as reduced metabolic acid production or reduced excretion of HCO3- is responsible for the increased pH:
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What does acidosis involve?
What does it activate?
How are normal levels restored?
Acidosis involves increased [H+] within the blood, resulting in increased activation of respiratory chemoreceptors and increased respiratory activity (compensatory hyperventilation). The resulting increase in CO2 removal from the blood/body increases blood pH until normal level are re-established via negative feedback.
What does alkalosis involve?
What does it activate?
How are normal levels restored?
Alkalosis involves decreased [H+] within the blood, resulting in decreased activation of respiratory chemoreceptors and decreased respiratory activity (compensatory hypoventilation). The resulting accumulation of CO2 within the blood/body decreases blood pH until normal level are re-established via negative feedback.
What are the causes of respiratory acidosis?
Respiratory acidosis, is associated with pathological states involving chronic respiratory failure, hypoventilation, and accumulation of CO2, e.g. COPD, choking
What are the causes of respiratory alkalosis?
Respiratory alkalosis is associated with pathological states involving hyperventilation and excessive removal of CO2, e.g. anxiety- or altitude-induced hyperventilation.
What are the causes of metabolic acidosis?
Metabolic acidosis is associated with pathological states involving either excessive acid production (sepsis, ketoacidosis) or excessive excretion of HCO3 (renal failure).
What are the causes of metabolic alkalosis?
Metabolic alkalosis is associated with pathological states involving excessive consumption of basic substances (e.g. antacid abuse), excessive excretion of acid from the body (vomiting), deficient absorption of HCO3 from the gastrointestinal tract (chronic diarrhoea), or excessive reabsorption of HCO3 (renal dysfunction).
Describe the pathway of acidosis-induced hyperkalaemia
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Describe the pathway of alkalosis-induced vasoconstriction
- CO2 (via H+) acts as a vasodilator in blood vessels (cerebral arteries particularly sensitive)
- Hyperventilation = ↓CO2 and ↓H+ (alkalosis)
- Alkalosis causes vasoconstriction of cerebral arteries
- ↓ cerebral blood flow = headache, lightheadedness, confusion, seizures
