Neuro-physiology Flashcards
What is the CPP range for autoregulation of cerebral blood flow?
Its belived to be between 50 and 150 mmHg.
What is the normal cerebral blood flow during autoregulation?
50ml/100g/min.
What happens to the CBF when CPP go under 50mmHg?
It goes down.
What happens to CBF when CPP goes over 150mmHg?
It goes up.
What is CMRO2?
cerebral metabolic rate of oxygen consumption
What is the CBF:CMRO2 ratio in quiescent brain?
14:18.
What happen with CBF and CMRO2 upon focal cortical activity?
Local CBF increase with aboout 30% and CMRO2 increase with about 5%.
How is the CBF calculated?
Its CPP/CVR or (MAP-ICP)/CVR
How is CPP calculated?
Its MAP-ICP
How is MAP calculated?
It is ((DBPx2)+SBP)/3
In reality, what is CVR representing?
It the resistance of the cerebral vascular bed.
When CPP is between 50-150mmHg, the CBF is kept constant. How?
The CVR is raised linear with the raised CPP of 50-150mmHg and in this way CBF is kept constant.
CBF= CPP/CVR as long as CPP is between 50-150mmHg.
What two factors affect CVR and change it?
- PaCO2 - there is a linear raise of CBF with increase of PaCO2 between 20-80mmHg.
- CVR is affected by changes in CPP -changes in vessel tone is produced via a myogenic mechanism.
WHat does a CBF of over 60 ml/100g tissue mean?
Hyperemia
