This lecture discussed the brain’s critical need for oxygen and how disruptions in blood flow can lead to brain lesions.
Key Points:
- The brain, despite being 2% of body mass, uses 25% of our oxygen.
- Unlike other tissues, brain cells (neurons) cannot regenerate if they die due to oxygen deprivation.
- This vulnerability is evident at high altitudes where reduced air pressure limits oxygen intake, causing acute mountain sickness.
Blood Flow and Cerebral Perfusion Pressure (CPP):
- Blood flow in most organs depends on the difference between arterial and venous pressure.
- Inside the skull, however, intracranial pressure adds another factor.
- Due to high intracranial pressure, cerebral perfusion pressure (CPP) relies on the difference between arterial pressure and intracranial pressure, not arterial and venous pressure.
- Low CPP due to either a drop in arterial pressure or a rise in intracranial pressure can lead to insufficient blood flow to the brain.
Consequences of Disrupted Blood Flow:
- Insufficient blood flow (ischemia) deprives neurons of oxygen, leading to cell death and brain lesions.
- Symptoms of low CPP include fainting (syncope) due to loss of consciousness and inability to maintain posture.
Next Lecture:
- The lecture will explore the blood supply to the brain in detail.