6 Flashcards
(39 cards)
Although only 2% of weight…how much does brain consume energy?
15-20%
what is the major metabolic need for neurons?
transport
Are neurons dependent on insulin?
NO
Does the brain use large stores of glycogen and oxygen?
no
What is the normal rate of blood flow for 100gm of nervous tissue?
40-55 ml/min
What characteristic of the brain is defined by an intrinsic mechanism that regulates vessel diameter so that relatively constant blood flow in the brain is maintained in spite of variations in anatomic metabolic conditions?
Autoregulation- large spikes of BP systemically can have very little effect in the brain
True or False- the range of blood pressure fluctuations beyond which cerebral flow is affected is broader in individuals with arteriosclerosis of cerebral vessels?
False- it is narrower
When auto regulation fails, cerebral flood flow has a linear relationship with BP. What might cause this to occur?
Old age- decreased CBF
Epilepsy- increased CBF 2-3x
Arteriosclerosis- severe decrease CBF
An increase of CO2 in brain leads to?
vasodilation and increase in CBF
What syndrome- after prolonged ischemia, normal CO2 response fails and blood flows away from that region?
Steal syndrome
What happens in a marked decrease of arterial O2 in the brain>?
increase flow to that region
What does low pH do to blood flow in the brain?
it causes an increase in flow to that region
Is blood flow greater in gray or white matter?
gray matter
When does sympathetic regulation become important to CBF?
outside the bounds of autoregulation—very heavy exercise
True or false- CBF is directly proportional to viscosity?
false- it is inversely
What is the difference between CT/MRI and PET/fMRI/SPECT?
The latter reflect metabolic activity and blood flow
Does the CSF help to regulate CBF?
yes
What is the flow path of CSF creation and distribution?
Lateral Ventricle>interventricular foramen of monroe>3rd ventricle>cerebral aqueduct of sylvius>4th ventricle>foramina lushka and foramen magendie>cisternae>some spinal cord>arachnoid villi>superior sagital sinus
What are enlargements of subarachnoid space called?
cisterns
Where is choroid plexus seen?
lateral ventricle(except anterior horn) 3rd and 4th ventricle
What are other sources of CSF production?
ependyma, cerebral pia,
Where is the major site of absorption of CSF?
arachnoid granules
What are the 2 major functions of CSF?
- Physical support–buoyancy/cushion
2. CNS Homeostasis- ions, pH, glucose
Does CSF cycle through more than once a day?
YEs- total V= 150 and rate of formation is 500-600ml /day
