Blood Supply of the Brain Flashcards
What artery supplies most of the cerebrum?
The Internal Carotid.
What does the internal carotid bifurcate into?
The anterior and middle cerebral arteries.
What supplies the brainstem, cerebellum and the spinal cord?
Vertebrobasilar arteries
What forms the basilar artery?
Fusion of the vertebral arteries
What does the Basilar artery bifurcate into?
The posterior cerebral arteries.
Circle of Willis
Interconnects the anterior and posterior circulations (as well as intracranial-extracranial anastomoses)
What supplies the deep cerebral structures?
Small perforating arteries which are formed from arteries around the base of the brain.
What does ANTERIOR circulation supply? POSTERIOR?
Anterior- Cerebral Cortex
Posterior- Brainstem and Cerebellum
Where do most strokes occur?
80% of strokes occur in spaces which are supplied by the internal carotid.
What is one important benefit to the Circle of Willis?
Though most people don’t have a full circle, the benefit is that if there is a blockage, blood can sometimes work its way around to still reach brain tissue.
High blood pressure often affects what types of arteries?
The small ones
What is the functional component for the blood brain barrier (BBB)?
Endothelial cells with tight junctions. They don’t let anything through.
Astrocytes
Star shaped glial cells in the brain and spinal cord which, among other duties, support the endothelial cells that form the BBB. They often have “vascular feet” that physically connect them to capillary walls.
What percentage of the body’s WEIGHT is the brain, and what percentage of OXYGEN and CARDIAC OUTPUT does in consume?
What does this mean?
The brain is 2% of the body’s weight, but uses 35% of its oxygen and gets 15% of its cardiac output.
This means that the brain can regulate the movement of nutrients that come to it and adjust blood flow based on metabolic demands.
Autoregulation vs Metabolic regulation of blood flow in brain
AUTO- arterial and smooth muscle cell mediated
METABOLIC- Increased neuronal activity leads to glutamate release which leads to astrocyte feet receptors becoming activated and releasing of vasodilator factors.
