BBB, CSF, Glymphatic System Flashcards
• Be able to describe the components of fluid compartments of the brain and its relationship to the circulatory system
• Intracellular, interstitial, and cerebrospinal fluid. Once something gets past the BBB/CSFB, it goes into the interstitial space. The glymphatic system feeds from interstitial to post capillary venules—cerebral veins—blood—back to heart and lungs (loop). The intracellular includes neurons and neuroglia and the CSF compartment goes to arachnoid villi then blood
• Be able to define the neurovascular unit and name its components
• Specialized vascular structures that make the bbb selective. Endothelium cells surrounded by smooth muscle cells then a leptomeningeal sheet and tightly packed astrocyte end feet. Pericytes make the protective basement membrane and form the basal lamina. They also have tight junctions
• Be able to define the blood brain barrier (BBB)
• Highly selective semipermeable border of endothelial cells that prevents solutes in the blood from non-selectively crossing into the extracellular fluid of the central nervous system where neurons reside.
• Be able to describe the neurovascular components of the BBB
• Cerebral microvascular endothelium, astrocytes, pericytes, neurons, and extracellular matrix.
• Be able to list the determinants of BBB crossing and predict whether a substance can cross the BBB
Small Positive Fat: Lipid soluble substances can diffuse but permeation decreases with increased MW. Must also have a positive charge. Facilitative and energy dependent receptor mediated transport of specific water soluble substances, ion channels.
• Be able to describe the function of cerebrospinal fluid (CSF)
Buoyancy (brain is heavy, without CSF it would crush neurons and cut off blood supply. Protection from injury when jolted or hit. Homeostasis, regulation of the distribution of substances between cells of the brain and neuroendocrine factors. Clearing waste.
• Be able to compare and contrast the BBB and the CSF-brain barrier
• CSF-brain barrier: formed by choroid plexus cells and has two layers of endothelial cells but no tight junctions (more permissive). BBB: formed by brain capillary cells and has one layer of endothelial cells and tight junctions
• Be able to describe the formation of CSF
• Secreted in the cerebral ventricles by choroid plexuses CSF lines all ventricles except the cerebral aqueduct. Ependymal cells ultrafiltrate
• Be able to recognize the flow of CSF and identify the ventricular system
• CSF flows from choroid plexus to lateral ventricles through interventricular foramina of monro to third ventricle then cerebral aqueduct to fourth ventricle. Then central canal, foramina of Magedie, and Luschka into subarachnoid space. Within this, fluid flows down spinal canal and back over convexity of brain into sulci and Virchow-Robin spaces.
Rostral: subarachnoid space (spinal) to subarachnoid space (brain) through arachnoid granulations to superior sagittal sinus through dural lymphatics to deep cervical lymph nodes
• Be able to describe how CSF exits into the venous system
• Absorbed through arachnoid granulations and villi (one way valves) then reenters veinous system
• Be able to define Circumventricular Organs and list their known functions
MOP N ASS They are relatively permeable to CSF-brain interface. Median Eminence
Organum Vasculosum
Pineal - melatonin release
Neurohypophysis- oxytocin and antidiuretic hormone
Area Postrema - vomiting
Subcommissural Organ
Subfornical Organ
• Be able to describe the exchange process between CSF and interstitial fluid
• Intersitital fluid is secreted continually at BBB and flows along a resistance pathway through tortuous extracellular space and enters ventricular CSF across ependymal lining of ventricles or subarachnoid CSF across pia
• Be able to identify meningeal lymphatic drainage
network of vessels along the dural sinus in the dura which express lymphatic endothelial cell marker proteins. Meningeal lymphatic vessels drain down and exit skull along dural venous sinuses and meningeal arteries.
• Be able to describe the role of the glymphatic system in brain waste clearance
Macroscopic waste clearance pathway that utilizes perivascular tunnels formed by astroglial cells to promote efficient elimination of soluble proteins and metabolites from the CNS
