Respiratory: Control of breathing Flashcards Preview

ESA 3 > Respiratory: Control of breathing > Flashcards

Flashcards in Respiratory: Control of breathing Deck (7)
Loading flashcards...
1
Q

What is hyperventilation and hypoventilation?

A

There is a mismatch:
In hyperventilation there is an increase in ventilation without a change in metabolism, leading to increased O2 and decreased CO2 - resp alkalosis
In hypoventilation there is a decrease in ventilation without a change in metabolism, leading to decreased O2 and increased CO2 - resp acidosis

2
Q

What is the effect of pCO2 on plasma pH?

A

If HCO3- is unchanged

  • an increase in pCO2 will cause pH to fall
  • a decrease in pCO2 will cause pH rise

There is a logarithmic relationship therefore small changes in pCO2 can cause big changes in pH

3
Q

What can cause a metabolic acidosis or metabolic alkalosis? How are they compensated?

A

Metabolic acidosis: If tissues produce acid it reacts with HCO3-, therefore HCO3- falls and pH falls.
(can be compensated forby increasing RR)

Metabolic alkalosis: HCO3- can rise after vomiting leading to a rise in pH.
(can only be partially compensated for by decreasing RR because this risks hypoxia)

4
Q

How do the central chemoreceptors detect a change in pCO2?

A

CO2 can diffuse across the BBB into the CSF then reacts with water to form HCO3- and H+ which is detected by the chemoreceptors

5
Q

What controls the levels of HCO3- in the cerebrospinal fluid?

A

The choroid plexus cells - however persistent changes to HCO3- conc which is corrected by the choroid plexus cells eventually leads to the ‘normal’ HCO3- conc being reset higher

6
Q

Is the BBB permeable to HCO3- and CO2?

A

HCO3- cannot cross

CO2 can readily diffuse across

7
Q

What changes occur (by chemoreceptors) when there is persisting hypoxia?

A

The hypoxia is detected by peripheral chemoreceptors and increases ventilation - however pCO2 will then fall causing decreased ventilation.
The CSF compensates for the high pCO2 and accepts it as normal
Therefore hypoxia becomes the driving force of ventilation

Decks in ESA 3 Class (96):