Cerebrospinal Fluid Flow: Basic Principles of the Glymphatic System Flashcards
How much cerebrospinal fluid do humans have?
Around 150 mL, renewed every 24 hours
What is the function of cerebrospinal fluid?
It protects the brain, like a cushion.
It helps in waste clearance.
During what physiological states does cerebrospinal fluid flow change?
Sleep vs wake
(more flow in sleep)
How does cerebrospinal fluid flow in the brain?
From the periaterial spaces, through aquaporings and gaps between astrocyte endfeet into the interstitial space and from there to the perivenous space.
What neurotransmitter is low during sleep and thought to affect cerebrospinal fluid? How does it affect cerebrospinal fluid?
Noradrenaline.
When noradrenaline levels are high (during wake) it reduces the interstitial space, because noradrenaline can modulate the size of astrocytes.
How does the glymphatic system change the conventional model of cerebrospinal fluid flow?
It includes the flow of CSF into the periarterial space, CSF-ISF exchange and the clearance through the perivenous spaces.
How does ischemic stroke relate to CSF flow?
Ischemic stroke is a good example of the fact that CSF flow to the brain is not always beneficial. One of the things that happen in ischemic strike is edema, and a part of this comes from the increase in PVS volume that happens when blood vessels collapse.
Edema is swelling caused by too much fluid trapped in the body’s tissues
What are the two main ideas of how the glymphatic system could be related to pharmacology?
Phamacodymamics: could we enhance glymphatic clearance by developing new drugs?
Phamacokinetics: could perivascular spaces act as a drug highway to the brain?
What is dexmedetomidine?
A sedative, that enhances glymphatic clearance, by decreasing the amount of noradrenaline in the brain causing sleep.
