Patho > CSF circulatory system/Brain Circulation > Flashcards

CSF circulatory system/Brain Circulation Flashcards

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1
Q

where is CSF contained

A

the arachnoid layer

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2
Q

columns that help hold up the arachnoid layer, allow for room for CSF to hang out

A

arachnoid trabeculae

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3
Q

what cells make CSF and where are they located

A

ependymal cells, located in the 4 ventricles

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4
Q

what is CSF made from

A

Na pumps in ependymal cells, chloride and water follows the Na

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5
Q

describe the pathway of the CSF draining in the ventricles

A

2 lateral ventricles drain to the 3rd ventricle, then the 3rd ventricle adds some CSF and it all drains into the 4th ventricle. From there is exits the ventricular system into the central canal

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6
Q

if we have an obstruction in a CSF ventricle what happens

A

the Na pumps dont stop, the CSF builds up, the ventricles expand, pressure on the neurons, damage. “hydrocephalus”

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7
Q

Middle Cerebral Artery

A

The Middle Cerebral Artery (largest branch of the internal carotid) supplies the lateral cerebral cortex, basal ganglia, and internal capsule. It’s the most common artery involved in stroke, producing contralateral face/arm deficits and aphasia or neglect depending on hemisphere dominance.

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8
Q

what 3 pairs of arteries make up the circle of willis

A

anterior cerebral arteries, middle cerebral arteries, and the posterior cerebral arteries

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9
Q

posterior cerebral arteries

A

-come off the back of the circle of willis
-close prox to brainstem
-lower/lateral brain (temporal lobe, occipital lobe visual cortex, vision and sound interpretation)

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10
Q

factors that contribute mostly to the cerebral blood flow regulation

A

CO2, O2, H+ ion concentration, substances released from astrocytes

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11
Q

Explain how excess of CO2 or H+ concentration increases cerebral blood flow

A

CO2 combines with water to form carbonic acid–> releases H+ ions–>dilate the cerebral vessels. directly proportional rise up to twice normal. Thus, any substances which contribute to acidity in the brain will lead to vasodilation (lactic acid, pyruvic acid, etc). Metabolism end products.

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12
Q

By increasing blood flow relative to rising H+ concentrations____

A

speeds the process of removing the CO2 or H+ to bring back to normal

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13
Q

CNS depression is a manifestation of ____ H+ concentration

A

increased

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14
Q

normal cerebral TISSUE PO2

A

35-45mmHG

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15
Q

how do vessels of brain tissue respond to PO2 <30mmHg

A

immediate increase in blood flow to cerebral tissues, similar to heart and skeletal muscle etc

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16
Q

normal range of MAP in cerebral vessels

A

50-150mmHg

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17
Q

autoregulation of cerebral blood flow, in a normal person

A

reductions in MAP to as low as 60 mmHg or increases to as high as 150 mmHg do not cause major changes in cerebral blood flow

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18
Q

explain what happens to a person’s cerebral blood flow autoregulation with chronic hypertension

A

the hypertrophic remodeling of cerebral blood vessels will shift the autoregulation curve to the right, allowing for a higher limit on the right but a resultingly lower limit on the left. Do not drop this person’s blood pressure too low or it is beyond the reach of the autoregulation and the brain will suffer from lack of perfusion

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19
Q

in cases of endothelial dysfunction or extreme hypertension, what happens to autoregulation?

A

the cerebral blood flow is not “pressure-dependent” and subject to pressure related damage (hyper or hypo tension - related damages to the brain including edema and hypoxia)

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20
Q

does sympathetic stimulation affect cerebral blood flow? why or why not?

A

sympathetic stimulation causes only mild or moderate changes in cerebral blood flow because the autoregulatory mechanisms are so strong that they override any sympathetic stimulation

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21
Q

where does sympathetic activation play an important role in cerebral blood flow control?

A

during times of strenuous exertion (exercise) a massive increase in MAP - the sympathetic response is capable of constricting the larger and intermediate sizzed brain vessels to prevent blood flow to the brain in amounts that could cause hemorrhagic cerebral stroke.

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22
Q

the number of capillaries and the rate of blood flow is ____ times greater in the ____ than the _____ of the brain. why?

A

4 times greater in the gray matter than the white matter because the neuronal cell bodies require much more metabolism than the myelinated white matter. vascular more concentrated on the outside of the brain than in???

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23
Q

what is a physiologic change in the cerebral vasculature that occurs over time in response to chronic hypertension

A

thickening of the small arterioles which lead to the capillary beds. this is to protect the capillaries from high pressures

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24
Q

blockage of the MCA on the left side of the brain:

A

Wernicke’s, Broca’s, motor control/spastic paralysis of the right side of the body

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25
how are the capillary beds of the brain less "leaky"
glial feet of the astroglial cells, supporting the capillary beds and preventing them from leaking or stretching too much in times of higher pressures
26
stroke involving the posterial cerebral artery
infarction of the occipital pole of the ipsiateral hemisphere of the damage, loss of vision in BOTH eyes in the half of the retina that is opposite side of the stroke
27
stroke involving the midbrain
blocks nerve condition in major pathways between brain and cord, leading to motor and sensory abnormalities
28
which artery mainly supplies the midbrain?
posterior cerebral artery superior cerebellar artery
29
how much CSF present at any given time is normal
150 mL
30
brain produces how much CSF average daily
500 mL
31
how does brain anatomy adjust for increased CSF pressure?
arachnoid granules act as "pop off valves", allowing for excess CSF to drain into the super sagittal sinus
32
where can CSF be found (normally)
ventricles of the brain, the cisterns around the outside of the brain, the subarachnoid space on the brain and spinal cord.
33
why does the brain simply float in the brain cavity?
brain and CSF have nearly the same specific gravity
34
functions of the CSF
Cushion the brain
35
contrecoup
when a blow to the head is severe, the damage to the brain may not be done to the side of the blow, but is likely to damage the opposite side bc the brain's inertia causes a momentary vacuum on the opposite side in the cranium and the brain will then come into contact with the skull on that side
36
which ventricle produces the most CSF
the 2 lateral ventricles
37
the last passage of CSF before the cisterna magna
foramen of magendie
38
cisterna magna lies ___the medulla and ____ the cerebellum
behind, beneath
39
the cisterna magna is continuous with the
subarachnoid space
40
the CSF moves from the cisterna magna to the
subarachnoid space surrouding the brain and spinal cord
41
CSF flows into the through the ____ projecting into the sagittal venous sinus
arachnoid villi
42
other than the Na pump which creates the CSF, other transport processes move small amounts of ____ into the CSF and both ____ and ____ out of the CSF and into the capillaries
-glucose -potassium and bicarb ions
43
CSF Vs Plasma characteristics:
osmotic pressure = Na = Chloride 15%> in CSF K 40% < in CSF glucose 30% < in CSF (bc it is quickly utilized)
44
why is glucose so heavily utilized by brain
only source of energy - only about a 2 minutes supply of glycogen stores. minute by minute delivery necessary to keep up with neurons.
45
what are arachnoid villi
small fingerlike projections INWARD to the venous sinuses
46
what can flow thru arachnoid granulations
CSF, proteins, and red and white blood cells
47
arachnoid villi allow CSF to flow into the venous system when it reaches pressure about ____ mmHg greater than the pressure in the venous sinuses
1.5 mmHg
48
arachnoid villi allow for bi or unidirectional flow?
unidirectional. one-way valves, do not allow blood in, only CSF out
49
what is normal CSF pressure per Dr Schmidt?
8-12 mmHg
50
how can hemorrhage or infection cause increase in CSF pressure
red or white blood cells can cause blockage of the arachnoid villi channels
51
communicating hydrocephalus
CSF flows thru the ventricles but there is a blockage in the subarachnoid spaces in the basal regions of the brain or blockage in the arachnoid villi. swelling occurs from outer layer, compressing the brain
52
noncommunicating hydrocephalus
CSF flow thru ventricles is blocked, usually in the aqueduct of Sylvias caused by atresia (from birth defect or tumor). Head swells from the ventricles, flattening the brain against the skull. Babys head will swell due to the skull not being fused yet.
53
explain tight junctions
tightly bound endothelial cells of the capillaries in the the brain tissues, unlike the loosely bound endothelial cells of the other areas of the body
54
what is the BBB nearly impermeable to and what is the downside to this?
plasma proteins and non-lipid-soluble inorganic compounds. ie. lots of drugs difficult to achieve therapeutic concentrations, example of protein antibodies
55
describe the vicious - cycle positive feedback loop involved with a concussion and subsequent brain edema
1. capillaries are damaged, begin to leak, edema compresses vasculature, dcrs blood flow, increase ischemia, increases dilation further, increased pressure, more leaking 2. Increased pressure, decreased O2 delivery, which increases the permeability of capillaries further, allowing more fluid leakage. Less ability to perfuse leads to less ATP. less ATP leads to less Na+ pump, leads to cellular swelling.
56
under resting but awake conditions, brain metabolism accounts for ____% of total body metabolism
15
57
what is the major need for metabolism by neurons
the ion pumps
58
O2 is required basically second by second bc of ____
high energy demand of the neurons
59
glucose transport to neurons is insulin dependent or independent?
independent
60
how would excess insulin affect the brain?
all of the insulin-dependent cells of the skeletal muscles and liver would take up the glucose, leaving none for the brain
61
what are the communicating arteries in the circle of willis
the anterior communicating artery and the posterior communicating arteries
62
sudden vision loss but intact motor function would probably be a result of blockage of what cerebral artery
posterior cerebral artery
63
the circle of willis provides collateral flow between which two major arterial systems
internal carotids and vertebrobasilar
64
65
How many **posterior spinal arteries** are there, and what do they supply?
Two posterior spinal arteries, each supplying ~12.5% (total ~25%) of spinal cord flow ## Footnote This indicates the contribution of posterior spinal arteries to the overall blood supply of the spinal cord.
66
How much of the spinal cord does the **anterior spinal artery** supply?
About 75% of total spinal cord blood flow ## Footnote The anterior spinal artery plays a crucial role in supplying blood to the majority of the spinal cord.
67
Where does the **anterior spinal artery** run?
Along the anterior median fissure, sending sulcal arteries into the anterior gray matter ## Footnote Its location is vital for its function in supplying blood to the spinal cord.
68
Why is loss of **anterior spinal artery perfusion** so dangerous?
It supplies most of the motor regions—occlusion causes motor paralysis and severe ischemic injury ## Footnote This highlights the critical importance of the anterior spinal artery in maintaining motor function.
69
What are **feed arteries** also called?
* Segmental * Medullary * Radicular ## Footnote These terms describe the various names used for feed arteries that supply the spinal cord.
70
What do **feed arteries** supply?
Both the anterior and posterior spinal arteries ## Footnote Feed arteries are essential for the vascular supply of the spinal cord.
71
Where do **feed arteries** run?
On top of the dura mater, over the dorsal root ganglia and anterior nerve roots ## Footnote Their positioning is important for their function in supplying blood to the spinal cord.
72
Do we have **feed arteries** at every spinal level?
Yes, but not all extend to the spinal arteries—high variability person to person ## Footnote This variability can affect individual vascular anatomy.
73
What are the **cervical feed arteries** derived from?
Vertebral arteries ## Footnote Understanding the origin of cervical feed arteries is important for vascular anatomy.
74
What are the **thoracic feed arteries** derived from?
Intercostal arteries ## Footnote This knowledge is crucial for understanding the vascular supply in the thoracic region.
75
How many **feed arteries** typically supply the **anterior spinal artery**?
About 2–3 feed arteries ## Footnote This indicates the typical number of feed arteries contributing to the anterior spinal artery.
76
How many **feed arteries** typically supply the **posterior spinal arteries**?
About 2–3 feed arteries ## Footnote Similar to the anterior spinal artery, the posterior spinal arteries also receive a limited number of feed arteries.
77
Is spinal cord vascular anatomy **consistent between people**?
No—highly variable ## Footnote This variability is emphasized in studies of spinal cord vascular anatomy.
78
What is another name for the **Great Radicular Artery (GRA)**?
* Great Medullary * Segmental * Radicular Artery of Adamkiewicz ## Footnote These alternative names reflect the significance of the GRA in spinal cord perfusion.
79
Between which vertebral levels does the **Artery of Adamkiewicz** usually enter?
Typically between T9 and T12, but can range T5–L5 ## Footnote This variability is important for surgical considerations and understanding spinal cord blood supply.
80
From which side does the **GRA** most commonly enter?
Left side ## Footnote This anatomical detail is significant for understanding the vascular supply to the spinal cord.
81
What part of the spinal cord does the **GRA** supply?
It feeds the anterior spinal artery, supplying the lower two-thirds of the spinal cord ## Footnote This highlights the critical role of the GRA in spinal cord perfusion.
82
Why is the **GRA** clinically significant?
Occlusion causes anterior spinal artery ischemia and paralysis ## Footnote Understanding the clinical implications of GRA occlusion is vital for patient management.
83
Why is the **GRA** important during **aortic aneurysm repair**?
Clamping above its origin risks spinal cord ischemia/paralysis; clamping below is generally safer ## Footnote This knowledge is crucial for surgical planning and preventing complications.
84
Can **CT imaging** always identify the GRA’s origin?
It can identify it but not always possible in emergencies ## Footnote This limitation can impact clinical decision-making in urgent situations.
85
How do surgeons preserve spinal cord perfusion during **aortic clamping**?
Lower CSF pressure via lumbar drain to increase perfusion gradient ## Footnote This technique is essential for maintaining spinal cord blood flow during surgery.
86
What is the **spinal cord perfusion pressure equation**?
Perfusion Pressure = MAP – CSF Pressure ## Footnote This equation is fundamental for understanding spinal cord blood flow dynamics.
87
Typical spinal cord **MAP range**?
60–125 mmHg ## Footnote This range is important for assessing spinal cord perfusion.
88
How does spinal cord **autoregulation** compare to cerebral autoregulation?
Present but narrower and less efficient, since the cord isn’t encased in a rigid skull ## Footnote This difference has implications for how blood flow is managed in the spinal cord.
89
What are **coronal arteries**?
Superficial arterial branches that encircle the cord’s surface ## Footnote These arteries contribute to the vascular supply of the spinal cord.
90
How many **spinal veins** are there and where are they?
One anterior and three posterior spinal veins, mirroring the arteries ## Footnote This arrangement is important for venous drainage of the spinal cord.
91
How do **feed arteries** relate to the dura and spinal nerves?
They run over the dura and follow the spinal nerve roots ## Footnote This relationship is crucial for understanding spinal cord vascular anatomy.
92
Are **feed arteries** always connected to the spinal arteries?
Not always—connections vary by level and individual ## Footnote This variability can affect the vascular supply to the spinal cord.
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