12 Questions
What is the normal amount of Cerebrospinal Fluid (CSF) in the human body?
150 ml
Where is CSF formed in the body?
Choroid plexuses in the ventricles
Which of the following is true about the constituents of CSF?
Higher concentration of anions like chloride compared to plasma
What process is involved in the formation of CSF?
Active transport
What effect does Isotonic Saline injection have on CSF formation?
Stimulates CSF formation
How does Hypertonic Saline affect CSF formation?
Decreases CSF formation
What is the color of cerebrospinal fluid?
Clear
Which of the following statements is true about the composition of CSF?
CSF contains organic and inorganic substances
Where is the greater portion of cerebrospinal fluid circulated after passing through the 4th ventricle?
To the cerebral hemispheres
How is cerebrospinal fluid mostly absorbed from the subarachnoid space?
By filtration into dural sinuses and spinal veins
Which event can increase CSF pressure by decreasing absorption according to the text?
Sneezing
What pressure does CSF exert in lateral recumbent position according to the text?
$5$ cm of H2O
Study Notes
Cerebrospinal Fluid (CSF)
- CSF is a fluid contained in the central canal of the spinal cord, subarachnoid space, and cerebral ventricles, and is a part of the extracellular fluid (ECF).
- The normal amount of CSF is around 150ml, with a range of 100-200ml.
Composition of CSF
- CSF consists of 99.13% water and 0.87% solids, which include organic and inorganic substances.
- Organic substances present in CSF include proteins, amino acids, sugar, cholesterol, urea, uric acid, creatinine, and lactic acid.
- Inorganic substances present in CSF include sodium, calcium, potassium, magnesium, chloride, phosphate, bicarbonate, and sulfates.
- CSF contains more sodium than potassium.
- CSF also contains lymphocytes, which are added when it flows into the spinal cord.
Site of Formation and Mechanism
- CSF is formed by the choroid plexuses situated within the ventricles, mainly in the lateral ventricle.
- The mechanism of CSF formation involves active transport, which requires energy expenditure, and does not involve ultrafiltration or dialysis.
Factors Affecting CSF Formation
- Pilocarpine, ether, and extracts of the pituitary gland stimulate the secretion of CSF.
- Isotonic saline injection also stimulates CSF formation.
- Injection of hypotonic saline increases CSF formation, while hypertonic saline decreases CSF formation and pressure.
Properties of CSF
- CSF is a clear, colorless, transparent fluid.
- The volume of CSF is around 150ml.
- The rate of CSF formation is 0.3ml per minute.
- The specific gravity of CSF is 1.005-1.006.
- The reaction of CSF is alkaline.
Circulation and Absorption of CSF
- CSF formed in the lateral ventricles passes through the foramen of Monro into the 3rd ventricle, and then into the 4th ventricle via the aqueduct of Sylvius.
- CSF then enters the cisterna magna and cisterna lateralis through the foramen of Magendie and foramen of Luschka.
- The majority of CSF is absorbed by the arachnoid villi into dural sinuses and spinal veins.
- A small amount is absorbed into cervical lymphatics and perivascular spaces.
- The mechanism of absorption is by filtration due to a pressure gradient between the hydrostatic pressure in the subarachnoid space fluid and the pressure in the dural sinus blood.
Pressure Exerted by CSF
- CSF exerts a pressure of 10-18cm of H2O in the lateral recumbent position and 30cm of H2O in the sitting position.
- Certain events like coughing, crying, and compression of the internal jugular vein increase the CSF pressure.
Explore the definition and constituents of Cerebrospinal Fluid (CSF). Learn about the normal amount, components including cells, proteins, anions, and glucose. Understand how CSF differs from plasma in terms of electrolyte concentrations.
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