Cerebrospinal Fluid Flashcards
major fluid of the body
cerebrospinal fluid
physiologic function
supply nutrients
remove metabolic waste
mechanical barrier; cushion brain & SC
3 basic function
Mechanical protection
Chemical protection
Circulation
appearance of csf
clear, colorless liquid
csf is composed of
water
csf carries
glucose, proteins, lactic acid, urea, cations, anions, WBC
volume of csf adult
80-150mL
volume of csf neonates
10- 60mL
- shock-absorbing medium
- protects
- fluid buoys the brain so that it “floats”
Mechanical protection
- optimal chemical environment
- neuron signaling
Chemical protection
exchange of nutrients and waste products
Circulation
brain and spinal cord are lined by
meninges
hard mother layer of meninges
lines skull and vertebral canal
dura mater
spiderweb-like layer of meninges
filamentous inner membrane
arachnoid
gentle mother layer of meninges
thin membrane lining the surfaces of brain and spinal cord
pia mater
csf is formed by/produced by
choroid plexuses
where in choroid plexuses csf is formed?
2 lumbar plexuses and 3rd 4th ventricles
csf flows through
subarachnoid space (between arachnoid and pia mates)
csf is reabsorbed in
arachnoid granulation
production of csf happens in
single layer of Ependymal cells
what happens in ependymal cells
selected amounts of plasma is filtered from capillaries and are secreted
- bidirectional
- filters blood to CSF
- accounts For production of csf
- transport metabolites
secretory capacity
- tight junctions by EPENDYMAL cells
- permits substances to enter the CSF but excludes others
Blood Cerebrospinal Fluid
- tight junctions OF capillary endothelial cells
- protection From materials/substances circulating in the blood
Blood Brain Barrier
- finger-like extensions
- gradual CSF reabsorption
Arachnoid villi/ granulation
reabsorption rate of csf
hourly: 20mL/ hour
daily: 480mL/day
csf is routinely collected by
lumbar puncture /spinal tap
3rd, 4th, 5th lumbar vertebra
spinal tap precautions
- movement of intracranial pressure
- prevention of infection of neural tissue damage
specimens are collected in 3 sterile tubes
① Clinical chemistry
② Microbiology
③ Hematology
tube 1
Clinical chemistry /serology
- least affected by blood or bacterial contamination
tube 2
Microbiology
- presence or absence of bacteria or pathogens
- make sure of the sterility
tube 3
Hematology
- perform cell count
- least likely to contain cells introduced by spinal tap
tube 4
- exclude skin contamination
- additional serologic testing
Microbiology
additional test for leftover supernatant fluid
chemical or serologic tests
contamination is caused by
norma Flora from the skin
storage for Clinical chemistry / serology
- Frozen / Freezing temp
to keep sterility
CSF glucose will be depleted if not preserved
storage for Microbiology
- room temperature
- cannot be frozen/refrigerated; pathogens will be killed
storage for Hematology
- refrigerated
storage for supernatant fluid
- Frozen
clarity is checked against
printed background
Appearance
-clear
Normal
Appearance
-increased protein & lipid concentration
-indicative of infection
turbid
appearance
presence of WBCS
cloudy
due to presence of RBC degradation products
Xanthochromic
slight hemolysis- slight amount of oxyhemoglobin
pink supernatant
heavy hemolysis; prolonged presence of oxyhemoglobin
orange supernatant
oxy hemoglobin → unconjugated bilirubin
yellow supernatant
- uneven
- Tl >T2 >T3
- least T3
Blood distribution
* traumatic tap
- evenly distributed between tubes clot formation
Blood distribution
* Inter cranial hemorrhage
clot formation
* Traumatic tap
- present due to fibrinogen
protein that promotes coagulation/clotting
fibrinogen
clot formation
* Inter cranial hemorrhage
- absent
Xanthochromic supernatant
* Traumatic tap
- absent supernatant
Xanthochromic supernatant
* Inter cranial hemorrhage
- present clear supernatant
RBCs must remain in CSF for ___ prior hemolysis
2 hrs
blood glucose shall be drawn out __ before spinal tap
2 hrs
Normal value of plasma glucose
60-70 %
decreased CSF glucose: determining cause of__
meningitis
increased CSF glucose
plasma elevations
low glucose, increased neutrophils
bacterial meningitis
low glucose, increased lymphocytes
tubercular meningitis
normal CSF glucose, increased lymphocytes
viral meningitis
- marker For meningitis
- contained within RBC
CSF lactate
> 35 mg/dL
bacterial meningitis
<25 mg/dL
viral meningitis
- tissue destruction within CNS
- oxygen deprivation/hypoxia
Increased CSF lactic acid levels
RBcs contain ___ of lactate and falsely elevated results maybe obtained on ___
high concentration; xanthochromic
normal concentration of csf glutamine
8-18 mg/dL
CSF glutamine is produced by
ammonia & alpha-ketoglutarate by brain cells
- remove toxic metabolic waste product ammonia
- indirect marker for ammonia in CSF
csf glutamine
