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Chapter 9 Cerebrospinal Fluid

Professor A. S. Alhomida

Chapter 9 Cerebrospinal Fluid

Professor A. S. Alhomida

DisclaimerDisclaimer• The texts, tables, figures and images contained in this course

presentation (BCH 376) are not my own, they can be found on: • References supplied• Atlases or• The web

King Saud University

College of Science

Department of Biochemistry

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Cerebrospinal FluidCerebrospinal Fluid

1. Cerebrospinal fluid (CSF) is a clear fluid present in the ventricles of the brain, the central canal of the spinal cord, and the subarachnoid space

2. Normal: almost no blood cells, little protein

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3. Its rate of formation, flow, and absorption is sufficiently high to cause its replacement several times daily Measuring its pressure, performing cell counts, and analyzing levels of various biochemical constituents is accomplished with a spinal tap

Cerebrospinal Fluid, Cont’dCerebrospinal Fluid, Cont’d

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4. An understanding of the formation, flow, and absorption of CSF is essential to an understanding of these diagnostic procedures and the pathophysiology of hydrocephalus

Cerebrospinal Fluid, Cont’dCerebrospinal Fluid, Cont’d

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1. A clear, colorless fluid that surrounds and permeates the CNS. Offers support, protection and nourishment

2. Functions:• Protection of cranial contents• Modulates pressure changes (same specific gravity

as brain)• Serves as a chemical buffer to maintain constant ionic

environment• Serves as a transport medium for nutrients and

metabolites, endocrine substances and even neurotransmitters

Cerebrospinal Fluid, Cont’dCerebrospinal Fluid, Cont’d

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Location of Cerebrospinal Location of Cerebrospinal FluidFluid

• Two lateral ventricles• Third ventricle• Fourth ventricle• Spinal cord central canal• Subarachnoid space• Continuous with

extracellular fluid of brain parenchyma

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Location of Cerebrospinal Location of Cerebrospinal Fluid, Cont’dFluid, Cont’d

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• Choroid plexuses of lateral, third and fourth ventricles

• Ependymal lining of ventricular system

• Pia-glial membrane• Blood vessels

Formation of Cerebrospinal Formation of Cerebrospinal FluidFluid

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• Cells are believed to actively secrete Na+

into the ventricular system in exchange for K+. Sodium ions electrically attract Cl- and osmotically draw water from the blood vascular system to constitute the CSF

Formation of Cerebrospinal Formation of Cerebrospinal Fluid, Cont’dFluid, Cont’d

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Cerebrospinal fluid collectionCerebrospinal fluid collection

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Composition of Cerebrospinal Composition of Cerebrospinal FluidFluid

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Clinical Significance of Clinical Significance of Cerebrospinal Fluid, Cont’dCerebrospinal Fluid, Cont’d

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Clinical Significance of Clinical Significance of Cerebrospinal Fluid, Cont’dCerebrospinal Fluid, Cont’d

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Correlation of Cerebrospinal Correlation of Cerebrospinal Fluid and SerumFluid and Serum

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Diagnostic of Cerebrospinal Diagnostic of Cerebrospinal FluidFluid

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Clinical Significance of Clinical Significance of Cerebrospinal Fluid TestsCerebrospinal Fluid Tests

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Blood-Brain BarrierBlood-Brain Barrier

• Direct injection of large molecules (e.g., a dye) into the venous system will often penetrate all tissues except the brain. This observation led to the notion of a physiological barrier to flow of substances from blood to brain tissue – the blood brain barrier

• The BBB functions to preserve a stable environment for neurons and glia of the CNS

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Blood-Brain Barrier, Cont’dBlood-Brain Barrier, Cont’d

1. Lipid soluble molecules will cross

2. Negatively charged molecules cross more freely than positively charged ones

3. High CO2/low O2 produce vasodilation and decrease resistance of BBB

4. Injury or inflammation decreases resistance of BBB (allows some antibiotics to be used for treatment)

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5. Selected brain areas are not protected by the BBB – the circumventricular organs (CVO) bordering on the 3rd and 4th ventricles

• parts of the hypothalamus - median eminence• Neurohypophysis• pineal gland• area postrema• subfornical organ• subcommissural organ

Blood-Brain Barrier, Cont’dBlood-Brain Barrier, Cont’d

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Blood – CSF BarrierBlood – CSF Barrier

1. Barrier from blood to the CSF2. Similar structural mechanism to the BBB

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-Globulins in CSF-Globulins in CSF

1. Recently considerable interest has been focused on the CSF changes of –globulins in multiple sclerosis

2. In multiple sclerosis there is a predominant increase in IgM and oligoclonal –globulin bands derived from plasma cells and lymphocytes are often present

3. In multiple sclerosis, the IgM antibodies may be antimyelin which accumulate in plasma of de-myelination

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Index of Index of –Globulins–Globulins

1. Attempts has been made to define an index which would give good discrimination between multiple sclerosis and neurosyphilis in one hand and other neurological conditions on the other

2. After estimation of -globulins by standard method, it is expressed as percent (%) of CSF proteins

3. Above 29% has been suggested as indicating multiple sclerosis and nuerosyphilis

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THE ENDTHE END

Any questions?