Physiology 8 Flashcards
what does the body do the maintain pH levels?
We need to maintain the ratio between HCO3 (bicarbonate) and carbon dioxide
How does the body control levels of carbon dioxide?
by using the respiratory system
how does the body control levels of bicarbonate?
by using the kidneys
What is respiratory acidosis?
A decrease in pH caused by the respiratory system
What is the cause of respiratory acidosis?
An increase in CO2
what are the acute causes of CO2 retention?
hypoventilation, barbiturates, opioids, obstruction.
What are the chronic causes of CO2 retention?
COPD, asthma, bronchitis
what is the response to respiratory acidosis?
An increase in PCO2 should be compensated by an increase in HCO3 by the kidneys.
In respiratory acidosis how do we get an increase in HCO3?
the increase in CO2 causes an increase in H+ ions that can be used to reabsorb and create new bicarbonate.
What is respiratory alkalosis?
this is an increase in pH caused by the respiratory system.
What causes respiratory alkalosis?
a decrease in PCO2
what causes an acute decrease in PCO2?
hyperventilation, aspirin, going to high altitudes
what causes a chronic decrease in PCO2?
living at high altitudes
How does the kidneys compensate to respiratory alkalosis?
The reduction in PCO2 is compensated. by the kidneys reducing HCO3 (this is easy because theres less H+ to create bicarbonate anyway)
What is metabolic acidosis?
This is a decrease in pH caused by the kidneys.
what causes metabolic acidosis?
a reduction in HCO3 from the kidneys
What causes a reduction in HCO3 from the kidneys?
the kidneys not reabsorbing or producing HCO3, more HCO3 being used as a buffer (if theres more CO2), diabetic ketoacidosis, kidney failure, diarrhoea
What is the respiratory response to metabolic acidosis?
the respiratory system decreases PCO2 in response to a decreased HCO3, it does this by blowing off more CO2.
What is kussmal breathing?
This is when the respiratory system increases depth of breathing to blow off more carbon dioxide - it is a sign of metabolic acidosis - by either chronic kidney disease or diabetic ketoacidosis.
How does the respiratory system delay the correction of the metabolic acidosis by the kidneys?
because the respiratory system blows off more carbon dioxide to maintain the pH, this reduces the H+ available to create more HCO3 so it takes longer for the kidneys to increase HCO3 to correct the original problem
What is metabolic alkalosis?
this is an increase in pH due to the kidneys increase in HCO3 (its more likely to be caused by a reduction in H+)
what are causes of metabolic alkalosis?
(reduction in H+): vomiting, aldosterone, liquorice.
how does the respiratory system compensate to metabolic alkalosis?
increase the PCO2 (reduced breathing)
what is the difference between acute and chronic metabolic alkalosis and acidosis?
there is none - because compensation via the respiratory system is instant (occurs within minutes)
what is the difference between acute and chronic respiratory acidosis and alkalosis?
the acute kidney response:
the only thing the kidneys can do initially is lose protons via titratable acids
the chronic kidney response: the kidney can make glutamine to be created into NH3 to be used to remove H+
What pH is worse, acute or chronic respiratory problems?
The acute pH is always more dramatically affected, because the kidneys take a while to properly respond and compensate
What happens when you vomit or have diarrhoea?
You lose both acid and alkali but you will become alkalotic
Why do you become alkaloitic in vomiting or diarrhoea?
because your body volume reduces - this increases renin and this increases aldosterone - aldosterone increases sodium reabsorption and increases potassium excretion and increased Hydrogen excretion.
the increased hydrogen excretion causes the alkalosis.
