Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
68 Cards in this Set
- Front
- Back
What are the layers of the dura mater?
|
an external, endosteal, and an internal,
meningeal, layer. These two layers are grossly indistinguishable; however, their bilaminar nature is apparent in those regions where they are separated by the large cerebral venous sinuses |
|
serves as the periosteum of the inner table of
the skull and is rich both in blood vessels and nerves |
external/endosteal layer of dura
|
|
The falx cerebri, falx cerebelli, tentorium cerebelli, and diaphragma sella are portions of what?
|
internal/meningeal layer of dura
|
|
Innervation of dura
|
a. The supratentorial portion - sensory innervation is provided by branches of the
trigeminal nerve. b. The infratentorial portion - sensory innervation is provided by the meningeal branches of the vagus and by the meningeal branches of the first three cervical nerves. |
|
Does the spinal dura also have 2 layers?
|
The spinal dura
consists only of this one layer as the vertebrae have their own separate periosteum. |
|
What is the leptomeninges?
|
Arachnoid membrane and pia mater
|
|
What are the arachnoid granulations?
|
The cerebral arachnoid sends tufted prolongations, called the arachnoid
granulations, through the inner layer of the dura into the superior sagittal sinus. It is through these granulations that the cerebrospinal fluid passes into the venous blood. |
|
Layers of spinal pia
|
inner intimal layer
(membranous) and an outer epipial layer (loose collagen fibers). Around the brain the epipial layer is poorly developed, consequently superficial arteries and veins of the cortex lie on the intimal pia in the subarachnoid space. |
|
What is the clinical relevance of the fact the epipial layer is poorly developed in in brain?
|
superficial arteries and veins
of the cortex lie on the intimal pia in the subarachnoid space. This is of clinical importance as these vessels are exposed to the CSF and thus, alterations therein can elicit vascular change. The presence of blood in CSF due to aneurysmal bleeding or other causes can trigger reactive vascular change leading to vasospasm. This decreases cerebral blood flow with serious CNS consequences. In the spinal cord, the blood vessels run within the epipial tissue. |
|
Which meningeal layer dips into the sulci of brain?
|
pia
|
|
midline third ventricle communicates with the midline fourth ventricle via
|
Sylvian aqueduct
|
|
Fourth ventricle communicates with the subarachnoid space via
|
foramina of Magendie and Luschka.
|
|
Communication between the two lateral
ventricles and the third ventricle is established through |
The paired foramina of Monroe
|
|
Lateral ventricles:
The anterior horn is roofed by the _______. Its medial wall is formed by the __________, while the floor and lateral wall are formed by the _____________. |
corpus callosum; septum pellucidum; head of
the caudate nucleus |
|
a thin space in the midline of the diencephalon, bounded by
the thalami and hypothalami. |
3rd ventricle
|
|
midline cavity whose floor is formed by the substance of
the medulla and the pons and whose roof is formed by the cerebellum. |
4th ventricle
|
|
Where are the choroid plexuses found?
|
within all the ventricles
|
|
How does CSF drain?
|
Drains thru the ventricles (lateral->3rd->4th) then thru paired lateral foramina of Luschka.to reach the subarachnoid space approximating the brain stem. From here, the fluid
travels upward in the subarachnoid space over the cortical convexities to reach the arachnoid granulations which protrude directly into the superior sagittal sinus or its related lacunae. In general, the CSF is under a 5-10 mm/Hg pressure, while the sinus pressure approximates 0. This pressure difference creates transcellular channels in arachnoid villi and allows the CSF to move into the venous return. |
|
What would happen if venous pressure rises?
|
CSF drainage would be impaired. CSF drainage depends on the higher pressure of the CSF to drain into the venous sinuses.
|
|
What does CSF have WAY less of than blood?
|
Amino acids, proteins, Igs
|
|
Subarachnoid hemorrhage from
ruptured aneurysm would include what in the CSF LP that's not normally there? |
RBCs
|
|
What would bacterial/fungal meningitis show in the CSF LP?
|
WBCs and lowered glucose
|
|
Elevated gamma globulins most likely IgG - discrete
subfractions forming oligoclonal bands in the CSF would be a sign of what? |
MS
|
|
T/F choroid epithelial cells are sealed by tight junctions
|
T
|
|
vascular supply of cerebral dura is mainly from _______
|
middle meningeal artery
|
|
purpose of Na/K pump sitting on surface facing CSF
|
Pumps Na in, pulls K out
(of CSF) |
|
T/F Brain become hypermetabolic – metabolism of brain can possibly outstrip blood flow.
|
T
|
|
2 major artery systems in the brain
|
Vertebral-basilar system and carotid system
|
|
What links the 2 systems?
|
posterior communicating artery
|
|
CN III is always found between what 2 arteries?
|
Posterior cerebral and superior cerebellar
|
|
Which vessel of the circle of Willis is mostly likely to be hypoplastic/nonfunctioning?
|
Typically, the posterior
communicating shows the most predilection for hypoplasia |
|
What arteries does the internal carotid a. give off after it goes thru the cavernous sinuses?
|
1) Ophthalmic
2) Posterior communicating 3) Anterior Choroidal 4) Anterior cerebral 5) Middle cerebral |
|
What arteries enter the cranial vault through the foramen magnum?
|
Vertebral
|
|
What arteries do the vertebral arteries give off?
|
1) PICA
2) Anterior spinal 3) Posterior spinal |
|
Branches of basilar artery (from fusion of 2 vertebrals)
|
1) AICA
2) Pontine arteries 3) Superior cerebellar 4) Posterior cerebral 5)Labyrinthine/auditory a |
|
T/F Cerebral veins parallel cerebral arteries
|
F
|
|
. Elevated PaC0 2 , lowered Pa0 2 or a
reduction in pH will cause _______. Lowered PaC0 2 or increased pH will cause __________________. |
vasodilation; vasoconstriction
|
|
Sympathetic input will cause ________. Limited parasympathetic
input will cause ____________. |
vasoconstriction ; vasodilation
|
|
What causes the BBB?
|
capillary endothelium
|
|
What are unique props of brain's vascular endothelium?
|
1. Unlike non-neural vascular beds, the brain's vascular endothelium lacks
fenestrations and vesicles. 2. Unlike many non-neural vascular beds, the brain's vascular endothelium is joined by continuous tight junctions. 3. Thus, the brain's vasculature appears as a continuous endothelial layer bound together by tight junctions. In essence then, the BBB can be viewed as a continuous lipoprotein plasma membrane. |
|
What do these sites have in common:
a. Choroid plexus b. Median eminence of the hypothalamus c. Subfornical organ d. Area postrema e. Pineal gland |
No BBB. Endothelium is fenestrated here.
|
|
cerebrovascular endothelium behaves as a____________
|
continuous lipoprotein membrane
|
|
T/F Lipid soluble non-
electrolytes would readily diffuse through such a membrane, whereas non-lipid soluble agents would not pass readily. |
T
|
|
T/F water diffuses thru BBB
|
T
|
|
T/F small ions diffuse thru BBB
|
F
|
|
T/F Glucose (D-glucose but not L glucose) readily crosses the BBB
|
T
|
|
T/F certain compounds are actively transported thru BBB in the blood --> brain direction
|
F. There is some evidence for certain things in the other direction tho
|
|
T/F BBB contains numerous enzymes which degrade
compounds moving through the vascular endothelium. |
T. Don't want active NTs to get into the BBB unless tightly controlled.
|
|
Where is the blood-CSF barrier?
|
choroid plexuses
|
|
How does glucose get into brain?
|
Glucose passes by facilitated diffusion through the wall of blood vessels and is
largely taken up by astrocytes. |
|
___________is the rate-limiting step in glycolysis during aerobic respiration
|
Hexokinase
|
|
What happens to the glucose that gets into the brain?
|
85% goes thru glycolysis for aerobic respiration
5% for glycogen storage 5% to pentose shunt |
|
Phospho-glucose isomerase
: significance of in brain |
Enzyme that uses G6P to enter aerobic pathway/glycolysis
|
|
What is the rate-limiting step for entering oxidative phosphorylation?
|
Pyruvate dehydrogenase
|
|
Which neurons are the most sensitive to hypoglycemia, and therefore the first to die ?
|
Glutamatergic neurons
|
|
What is astrocytes-neuron lactate
shuttle ? |
theorized to support rapid neuronal firing rates;
however, neurons will also perform glycolysis, particularly when at rest. Glucose taken up by astrocytes, which export lactate to neurons (also reduces NADH to NAD+ to facilitate glycolysis). Neurons convert lactate back to pyruvate to feed aerobic respiration. Astrocytes maintain glycogen reserve – used to produce extra lactate upon heightened demand |
|
What's the glutamate feedback loop?
|
Astrocyte processes sense level of glu that’s being released. If [glu] goes up, it calls for more glucose to be converted to lactate.
|
|
Prenatal brain relies on what process for energy?
|
glycolysis, not aerobic respiration.
|
|
T/F At birth, lipid
production increases and the brain becomes ketotic in response to the high fat content of mother’s milk. At this point ketones are a significant fuel source and the brain is actual hypoglycemic |
T
|
|
What's used for myelination?
|
ketones
|
|
Childhood brain uses ___ of oxygen consumed.
|
50%
|
|
T/F After about age 20, metabolism of brain is kept pretty constant unless there's a disease process
|
T
|
|
What happens in hyperinsulinemia?
|
Despite normal oxygenation
and blood flow, inadequate glucose will stop aerobic metabolism and if severe enough will end up in coma. (Free FAs decreased in this case too) |
|
What happens to neurons when ATP runs out?
|
ion pump function fails within a
few minutes (Fig. 5). Potassium exits the cell and sodium floods in. The cell membrane depolarizes within minutes and proton and calcium ion channels open. Once flooded with calcium, proteases will activate and induce cell death within minutes to hours. |
|
What is spreading depression?
|
dying neurons release K+ from their insides to ECM. This depolarizes surrounding neurons and causes their deaths.
|
|
What is excitotoxicity?
|
When dying neurons release glutamate, causing activation of NMDArs and opening of Ca2+ channels.
|
|
TPA is adminstered in cases of ______
|
ischemic stroke
|
|
Foramen of Magendia is _______ while foramen of Luschka is _________
|
medial; lateral.
Both are involved in draining CSF from 4th ventricle to subarachnoid space. |