Regulation of cerebral blood flow Flashcards
Gray vs white matter, greater flow?
Gray matter is twice as high
Average blood flow to cerebellum
50-100 my per 100 g of tissue
Name 3 mechanisms of regulation
- Autoregulation
- Neuronal control
- Chemical mechanisms
Autoregulation
Myogenic response = excess flow causes vasoconstriction
When must you be worried about the myogenic response?
Myogenic response results in constant blood flow within a certain BP range 70-100 mm Hg but can reset to higher level in patients with chronic BP 100-150 mm Hg. Be careful when lowering the patients BP, if done too quickly normal BP levels will cause hypoperfusion
2 mechanisms of neuronal control
Extrinsic nerves (sympathetic, parasympathetic and sensory nerves) - pial arteries lined with smooth muscles
Intrinsic Nerves release vasoactive substances
Locus coeruleus, raphe nucleus and nucleus basalis
An increase in CO2 causes
vasodilation
A decrease in CO2 causes (hyperventilation)
vasoconstriction
Metabolically active areas are more\less perfused
More (basis for MRI)
3 functions of BBB
Selective passage of ions
Maintain constant intracranial volume
Homeostasis
Which type of glial cells are responsible for the BBB
Macroglia, astrocytes
Astrocyte foot processes induce the formation of
tight junctions in capilaries
Most important factors that determine whether something can cross the BBB
Is there a channel that it can use?
Facilitated transport
Active transport
Name 1 area without a BBB
Median eminences Pineal Choroid Lamina terminalis Subfornical organ Chrois Area postrema
Is there a CSF - Brain barrier?
NO
