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Ana/Phys/Patho I > Unit 6: CNS circ systems - meninges > Flashcards

Unit 6: CNS circ systems - meninges Flashcards

1
Q

name the cranial meningeal layers (including structural components) from most superficial to most deep

A
  1. dura mater
  2. arachnoid layer
  3. subarachnoid space
    +arachnoid trabeculae
    +subarachnoid vasculature (cerebral arteries and veins)
    +CSF
  4. pia mater
  5. cerebral cortex
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2
Q

most SDHs are caused by what types of blood vessels?

A

veins
majority of SDH are venous bleeds associated with the venous sinuses in the brain

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3
Q

most epidural hematomas are caused by which type of blood vessels?

A

arteries
fracture to the cranial bone could cause major arterial bleeds and most epidural hematomas are arterial bleeds

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4
Q

most subarachnoid hemmorhages are caused by which type of blood vessels?

A

arteries

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5
Q

CSF electrolyte composition: pH and HCO3-

A

pH = 7.31: lower than plasma
HCO3-: lower than plasma

bicarb will help buffer the CSF d/t the high metabolism of CO2 by the brain cells

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6
Q

CSF electrolyte composition: Na+

A

140 mOsm/L
equal to plasma

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7
Q

CSF electrolyte composition: Cl-

A

very close to sodium
~140 mOsm/L
higher than plasma

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8
Q

CSF electrolyte composition: K+

A

40%< plasma

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9
Q

CSF electrolyte composition: Mg2+

A

higher than plasma values

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10
Q

the combination of Cl-, K+, and Mg2+ concentration levels will contribute to “limited neurological activity”, AKA, helps us to “pump the brakes” on our nervous system. why?

A

CSF Cl- [ ] > plasma
CSF K+ [ ] 40% < plasma
CSF Mg2+ > plasma

a higher Cl- [ ] will make the neuronal cells more permeable to chloride (d/t GABA receptors on axon hillocks) and will make the cells less excitable (functional brake system)

lower potassium: more hyperpolarized cell

higher mag: limits overactivity

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11
Q

CSF electrolyte composition: glucose

A

normal: 60mg/dL
(plasma: 90mg/dL)

glucose [ ] is lower in CSF than plasma for the following reasons:
the NS is constantly burning glucose, and main way to get glucose into the nervous system is via GLUT-1 transporters (facilitated diffusion), which is not generally a fast transportation system

since glucose goes along its [ ] gradient, the CV needs to have a higher glucose [ ] than the CSF (90mg/dL vs 60 mg/dL) SO THAT glucose diffuse into the NS

neurons CANNOT store glucose
CNS is very sensitive to glucose fluctuations

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12
Q

CSF sample color

A

clear

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13
Q

CSF average volume
(if quantified in a container)

A

150 ml

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14
Q

total CSF volume production per day

A

~500 ml/day
(produced about 3x a day)

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15
Q

what do ependymal cells do?

A
  1. produce CSF
  2. a “transition” area for ions to flow from blood to CSF
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16
Q

describe how different ions are transported in/out of ependymal cells

A

FROM BLOOD
1. leaky Na+ channels allow Na+ OUT of cell into blood
2. leaky Cl- channels allow** Cl- INTO cell from blood**
3. water can flow in/out of cell from blood

TO CSF
4. Na+ pump (via primary AT) out of cell to CSF
5. Cl- difffuses out of cell to CSF (dragged along with Na+)
6. water diffuses out of cell to CSF (follows Na+)

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17
Q

how can anesthetics increase/decrease the rate at which CSF is being produced in ependymal cells?

A

some anesthetics can increase or decrease the rate at which the primary AT Na+ pumps are pumping sodium out of the ependymal cell into the CSF

higher Na+ rate out = higher Cl- rate out = more water out

slower Na+ rate out = slower Cl- rate out = less water out

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18
Q

what do the astrocytes do in terms of CSF electrolyte managment?

A

regulates the K+ levels in the CSF

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19
Q

what is the name of the tissue that aggregates ependymal cells together to create CSF?

A

choroid plexus

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20
Q

where are choroid plexuses found?

A

the ventricles of the brain

21
Q

how many ventricles are there in the brain?

A
  1. left lateral ventricle
  2. right lateral ventricle
  3. 3rd ventricle
  4. 4th ventricle
22
Q

where are the ventricles in the brain located?

A

the lateral ventricles are encased in the cerebral hemispheres

the third ventricle is where the diencephalon is

the fourth ventricle is next to the cerebellum

23
Q

what is another name for the Interventricular Foramen?

A

Foramen of Monroe

24
Q

what is the Foramen of Monroe?

A

AKA the interventricular foramen

the pathway for the lateral ventricles to empty into the 3rd ventricle

25
Q

name the structure that drains the CSF from the 3rd ventricle to the 4th ventricle

A

cerebral aquaduct
or the Aquaduct of Sylvius

26
Q

another name for the Cerebral Aquaduct

A

Aquaduct of Sylvius

27
Q

what are the exit points for CSF to flow out of the 4th ventricle?

A
  1. central canal
  2. left lateral apertures
  3. right lateral aperture
  4. median aperture
28
Q

what is the other name for the Foramen of Luschka?

A

Lateral Aperture (2)

29
Q

what is the other name for the Median Aperture

A

Foramen of Magendie

30
Q

name the structure that is most prone to occlusion preventing CSF flow

A

Cerebral Aquaduct/
Aquaduct of Sylvius

31
Q

build up of CSF in the ventricles causing expansion of ventricles is called:

A

hydrocephalus

32
Q

differentiate non-communicating vs communicating hydrocephalus

A

non-communicating: block in the pathway of CSF flow

will see ventricular enlargement/expansion

communicating: no occlusions, but CSF is not absorbing as it normally would

will see generalized increase in ICP

33
Q

describe what the arachnoid granulations do

A

“pressure blow off valves”

ex) normal ICP 10; if ICP is 12, these “valves” will open to decompress and reabsorb CSF to CV circulatory system

34
Q

where else does CSF get reabsorbed?

A

vertebral venous plexus
endoneural space

(very little CSF gets reabsorbed here)

35
Q

what does the cerebellum do

A

coordinates complex motor functions

36
Q

where is the Cisterna Magna; what does it do?

A

this cistern surrounds the cerebellum and circulates the CSF around it – it does this becasuse the cerebellum is important for coordinated complex motor function and keeps the CSF surrounding it “fresh”

another name for the Cisterna Magnum is “Cerebellomdullary Cistern”

37
Q

what are the 7 major cranial sinuses?

A

superior saggital sinus
inferior saggital sinus
straight sinus
sinus confluence
transverse sinus
sigmoid sinus
cavernous sinus

SIS-SC-TSC

38
Q

what is the Falx Cerebri

A

connective tissue that separates the L and R hemispheres and extends to the back of the brain

39
Q

what is the Tenrtorium Cerebelli

A

it is a “shelf” for the occipital lobe to “sit on top of”

the cerebellum sits below this

40
Q

Sinus Confluence

A

“SC”

where the superior and inferior saggital sinuses && the transverse sinuses (L+R) “conference” together

41
Q

Sigmoid Sinus

A

the sigmoid sinus is the “S” curved sinus that pools the blood to the IJ veins

41
Q

Cavernous Sinus

A

a “pool” of blood collected in the front middle brain

“cavern” think: “pool”

42
Q

Straight Sinus

A

comes off the Inferior Saggital Sinus

43
Q

How many Transverse Sinuses are there?

A

2 (L and R)

44
Q

where do all the sinuses drain into?

A

the internal juguluar veins
(the external jugular veins empty the more superficial structures on the side of the head)

45
Q

what are the 4 major cranial arteries that feed the brain?

A

internal carotid artery (brain blood flow)
external carotid artery (superficial, facial)
2 verterbral arteries (front + back of neck to back of brain)

46
Q

what is the normal cerebral blood flow rate?

A

750 ml/min
(50 ml/min/100g of tissue)

47
Q

how much cerebral blood flow goes to the grey matter? to the white matter?

A

80% to grey matter (where decisions are made)

20% to white matter

48
Q

how much percentage of the CO is cerbral blood flow?

A

15%

Ana/Phys/Patho I (6 decks)

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