RESP- Integrated Control of Breathing

Question 1

how do the lungs and the kidney maintain blood pH homeostasis

Answer 1

regulating PaCO2 and HCO3

Question 2

respiratory acidosis / alkalosis is a result of

Answer 2

when a change in respiratory function causes a disturbance in pH

Question 3

respiratory acidosis occurs when

Answer 3

ventilation is insufficient relative to the metabolic demands of the body (in terms of carbon dioxide production)

Question 4

respiratory alkalosis occurs when

Answer 4

ventilation is excessive relative to the metabolic demands of the body (in terms of CO2 production)

Question 5

what are the causes of hyperventilation

Answer 5

anxiety - panic attack

Question 6

what are the causes of respiratory alkalosis

Answer 6

altitude - at higher altitudes PaO2 is decreased

therefore there is an increase in alveolar ventilation to try and correct the PaO2 and CO2 via hypoxic drive

increased ventilation decreases pCO2 causing alkalosis

Question 7

when does metabolic acidosis occur

Answer 7

when the production of acid is excessive or HCO3 is deficient

Question 8

what are the causes of metabolic acidosis

Answer 8

sepsis - infection causes decreased oxygen delivery to tissues = anaerobic respiration and therefore lactic acid build up

this causes acidosis - respiration increases in compensation

other:
diabetic ketoacidosis - fatty acid release from the liver due to low insulin
renal failure - decreased HCO3 reabsorption in proximal tubule
diarrhoea - decreases bicarbonate absorption in colon

Question 9

when does metabolic alkalosis occur

Answer 9

when there is excessive excretion of acid / excessive concentrations of HCO3

respiratory compensation

Question 10

what are the causes of metabolic alkalosis

Answer 10

diuretics - changes to H+ and HCO3 reabsorption
antacids - increase HCO3 consumption
vomiting - loss of H+ ions in the stomach

Question 11

what is an effect of respiratory acidosis

Answer 11

acidosis-induced hyperkalaemia

accumulation of K+ in serum - leads to cardiac arrythmias and muscle weakness

Question 12

what is an effect of respiratory acidosis

Answer 12

acidosis-induced hyperkalaemia

accumulation of K+ in serum - leads to cardiac arrythmias and muscle weakness

Question 13

what is the mechanism of acidosis-induced hyperkalaemia

Answer 13

acidosis = increase in extracellular H+ concentration

leads to a decrease in H+ concentration gradient

leads to decreases intracellular H+ excretion

therefore the Na / K+ exchanger leads to decreased potassium absorption and therefore increased potassium in serum

Question 14

what is an effect of respiratory alkalosis

Answer 14

alkalosis-induced cerebral vasoconstriction

Question 15

what is the mechanism of alkalosis-induced cerebral vasoconstriction

Answer 15

CO2 (via H+) acts as a vasodilator for blood vessels - cerebrak arteries are particularly sensitives
hyperventilation causes a decrease in CO2 and H+ = alkalosis

alkalosis causes constriction of arteries
leading to a decrease in cerebral blood flow = headache, light-headedness, confusion, seizures