Lecture 10/11 - CNS Circulatory Systems Meninges Flashcards
Exam 2
What is the downside of having the grey matter superficial in the brain?
Prone to concussion
Arterial vs venous bleed
Arterial bleeds get worse quicker, venous bleed slower to progress
The pia mater sits on top of _____ in the brain
Neural and glial cells, outside border of the brain
The space between the pia mater and the arachnoid mater is the ______. What is in this space?
Subarachnoid space - blood vessels and CSF
A subarachnoid hemorrhage is ______ in nature
arterial
aka arterial aneurysms
The ______ are the pillars that create space between the arachnoid and pia layers
Arachnoid trabeculaes - create space for CSF and blood vessels
A subdural hemorrhage is ______ in nature
venous - slower to develop, headache a couple days after trauma
A _______ is when the arterial blood vessels rupture with a skull fracture
Epidural hematoma
Which layer perfuses the skull?
The dura layer - cranial sinuses
What is the total volume of CSF?
150 mL
What is the rate at which the CSF is produced?
500 mL/day - replaced 3x a day on average
What cells are responsible for maintaining the electrolyte levels of the CSF?
Astrocytes
pH of CSF vs plasma
CSF pH more acidic
- blood 7.4
- brain 7.31
Why is the CSF more acidic than the blood?
- Lower bicarb level in CSF - more acidic
- Brain has its own buffer system with bicarb to remove CO2 that is produced through metabolism
Na levels of CSF vs plasma
140 - same
Cl levels of CSF vs plasma
Higher in CSF than plasma
Same as Na - 140
K levels of CSF vs plasma
40% less than normal plasma values - 2.4
The ______ doesn’t get refreshed with CSF as much as areas higher up
Lumbar cistern
Mg levels of CSF vs plasma
Higher in CSF
The changes in electrolyte concentrations in CSF helps keep the _____ on the NS
brakes
How do different electrolyte values in the CSF help keep the brakes on neurological systems?
Raising Cl - makes more (-) - hyperpolarized, GABA receptors
Lower K - hyperpolarized cell
Higher Mg - lower overactivity
Glucose levels of CSF vs plasma
Lower in CSF → 60 mg/dL
Plasma 90 mg/dL
Why is glucose lower in the CSF than in the plasma?
Glucose is transported into CSF via GLUT1 transporters
Follows concentration gradient (facilitated diffusion) so need CSF < plasma
- CSF uses glucose
- Neurons can’t store glucose as glycogen - need transport in
What are the units used for glucose concentration?
mg/dL