Neuronal plasma membranes are selectively permeable to _______, allowing it to move out of the cell down its conc gradient and creating a net _______ within the cell.
Membrane potential is established because _____ diffuses down its conc gradient out of the cell, but the ______ charge that builds within the cell attracts diffusing ______ against their conc gradient and back into the cell.
K+; negative; K+
Permeability of the membrane to _______ is low and constant; therefore, membrane potential is mainly controlled by __(2)__.
Cl-; Na+ and K+
Membrane potential is ______ (charge).
At rest, extracellular concs of __(2)__ are high relative to inside the cell.
Na+ and Cl-
Everywhere except _____________, the negative and positive charges are ____________.
adjacent to the surfaces of the cell membrane; exactly equal (electrical neutrality)
The _____________ establishes the high intracellular K+ conc and low intracellular _____ conc.
Na+K+ATPase pump; Na+
________________ is the primary basis for the -90mV membrane potential.
K+ diffusion down its conc gradient out of the cell
In the resting stage, the membrane is _________.
During membrane depolarization, the membrane suddenly becomes ____________, resulting in a massive influx; this leads to ______________.
more permeable to Na+; elimination of membrane potential
The influx of Na+ that leads to membrane depolarization is mediated by activation of ____________, which occurs through ____________ that caused a conformational change.
voltage-gated Na+ channels; reduction of the membrane potential (from -90 to -50)
The reduction in membrane potential necessary for activation of voltage-gated Na+ channels must be sufficient to _______________ and induce a ____________.
surpass threshold of activation; positive-feedback loop of voltage-gated Na+ channel acitvation
Depolarization will spread in __________ where ____________.
all directions; resting/polarized membranes are encountered
Repolarization is achieved due to the slow conformational change in a ___________. allowing ___________.
voltage-gated K+ channel; efflux of K+
Diffusion of ________ to the __________ re-establishes resting membrane potential.
Na+/K+ concs are re-established by the ___________.
__________ is the most efficient way to generate ATP; therefore, the brain does not utilize __________; the implication of this is...
_____________ occurs as ingrowth during embryogenesis and is necessary for nutrition and waste removal.
Doe grey or what matter have more vascularization and metabolic activity?
The BBB is permeable to... (2)
lipid soluble compounds, (slightly) electrolytes.
The BBB is impermeable to... (2)
plasma proteins, large (water soluble) organic compounds.
What is the anatomic basis for the BBB?
non-fenestrated capillary endothelial cells with tight junctions b/w cells
The basal lamina upon which the endothelium of the BBB rest is surrounded by ____________.
astrocytic foot processes
Functions of CSF. (3)
waste removal supply of metabolites, protective cushion for nervous tissue
The __________ is responsible for CSF production.
The choroid plexus is composed of specialized structures in the...
lateral ventricles and roof of the third and fourth ventricles.
Choroidal epithelia are specialized ___________ responsible for CSF production.
Capillaries of the choroid plexus have __________ endothelium, with __________ of the choroidal epithelium, creating the blood-CSF barrier.
fenestrated; tight junctions
For CSF production, _______ is actively transported into the ventricular system by the ___________, carrying __(2)__ along with it; __(2)__ are actively transported out of CSF.
Na+; Cl- and water; K+ and bicarb
What are the functions of CSF? (3)
waste removal, metabolite supply, protective function
The _______ of the brain and the ________ of the spinal cord contain CSF.
ventricular system; duct system
CSF is resorbed in the _________.
Describe the flow of CSF from where it is produced to the spinal cord.
lateral ventricles--> interventricular foramen--> third ventricle--> mesencephalic aqueduct--> fourth ventricle--> lateral apertures to the subarachnoid space--> spinal cord central canal
The subarachnoid space is created by the _________.
The tough fibrous connective tissue covering that protects the brain and spinal cord from penetrating injury and forms the periosteum of the interior surface of the cranial vault.
dura mater/ pachymeninges
The deicate collagen and reticular fibers that send supportive trabeculae to the pia mater.
arachnoid membrane/ leptomeninges
What are the 2 components of the leptomeninges?
arachnoid membane and pia mater
Layer of the meninges that is intimately associated with the surface of the brain and spinal cord.
The subarachnoid space is b/w the _________ and _________ and is filled with _________.
arachnoid membrane; pia mater; CSF
Glial cells of neuroectodermal origin that have apical cilia that cause the continuous movement of CSF into the subarachnoid space.
_________ lined by ependymal cells extend into the dorsal sagittal sinus, permitting the resorption of CSF.
The perivascular space is where ____________ occurs.
modification of CSF composition
The CNS corollary to lymphatics of other organ systems.
The perivascular space is potential space b/w the _________ and the __________.
endothelial basement membrane; basement membrane of the pia mater
Why does the CNS lack a classical lymphatic draining system, and how does it overcome this?
due to the presence of the BBB; when fluid escapes, it accumulates in the perivascular space and then passes through the subarachnoid space to the arachnoid vili to be resorbed
Due to the BBB, vascular leakage in the CNS occurs only in association with...
inflammation or other pathologic processes that increase vascular permeability.
Finger-like extensions of the arachnoid membrane that project into large venous sinuses; cells contain valve-like pores to permit unidirectional flow of material from the subarachnoid space into venous circulation.
_________________ is the primary determinant of CSF pressure.
Rate of absorption into arachnoid villi
Clusters of arachnoid villi.
CSF passing along cranial nerves and spinal nerve roots, going into lymphatics does not play a major role in CSF pressure; it does, however, play a major role in...
initiating adaptive immune responses for processes that begin in the CNS.