| 单词 | cerebrospinal fluid | |||
| 释义 | cerebrospinal fluidcerebrospinal fluidcerebrospinal fluidcerebrospi′nal flu`idn. cer·e·bro·spi·nal fluid(sĕr′ə-brō-spī′nəl, sə-rē′brō-spī′nəl)cerebrospinal fluid
Cerebrospinal Fluidcerebrospinal fluid[sə¦rē·brō′spīn·əl ′flü·əd]Cerebrospinal Fluidthe liquid that circulates in the ventricles of the brain and spinal canal and in the subarachnoid space (under the arachnoidea) of the brain and spinal cord. Cerebrospinal fluid is formed by vascular plexuses, glandular cells, the epen-dyma and subependymal tissue of the ventricles of the brain, the arachnoidea, and the glia. Drainage is through the venous plexuses of the brain, sinuses of the dura mater, and the perineural spaces of the cranial and spinal nerves. Cerebrospinal fluid serves as a water cushion that protects the brain and spinal cord from external forces. It regulates intracranial pressure and ensures the constancy of the internal medium. Tissue metabolism in the central nervous system is achieved through cerebrospinal fluid. In a healthy individual, the fluid is transparent and colorless. Adults have 100–150 milliliters of cerebrospinal fluid, which varies in specific weight from 1.006 to 1.007. The fluid is slightly alkaline, and its pressure varies at different levels of the central nervous system, depending on the position of the body. (Cerebrospinal pressure is 100–200 mm H2O in the horizontal position.) In its chemical composition, cerebrospinal fluid is similar to blood serum. It may contain from zero to five cells per cu mm and 0.22-.33 parts per thousand protein. The diagnosis and treatment of various conditions is facilitated by lumbar puncture, which permits cerebrospinal pressure to be measured and the fluid to be extracted for analysis purposes. Damage to the central nervous system alters the pressure and composition (especially the ratio between proteins and cells) of cerebrospinal fluid. Cerebrospinal pressure increases in cases of drainage disorders, which may be caused by traumas of the skull and spine, brain tumors, and hemorrhages. Bacteria are found in the fluid during meningitis. Lange’s test and the benzoin test are used in diagnosing syphilis. The biochemical analysis of the sugar, chlorides, free amino acids, and enzymes contained in cerebrospinal fluid is useful in the determination of neuroinfections and epilepsy. REFERENCESShamburov, D. A. Spinnomozgovaia zhidkost’. Moscow, 1954.Burgman, G. P., and T. N. Lobkova. Issledovanie spinnomozgovoi zhidkosti. Moscow, 1968. Makarov, A. Iu. Sovremennye biokhimicheskie issledovaniia likvora v nevrologii. Leningrad, 1973. V. B. GELFAND Cerebrospinal fluidcerebrospinal[ser″ĕ-bro-spi´nal]The cerebrospinal fluid aids in the protection of the brain, spinal cord, and meninges by acting as a watery cushion surrounding them to absorb the shocks to which they are exposed. There is a blood-cerebrospinal fluid barrier that prevents harmful substances, such as metal poisons, some pathogenic organisms, and certain drugs from passing from the capillaries into the cerebrospinal fluid. The normal cerebrospinal fluid pressure is 5 mm Hg (100 mm H2O) when the individual is lying in a horizontal position on his side. Fluid pressure may be increased by a brain tumor or by hemorrhage or infection in the cranium. hydrocephalus, or excess fluid in the cranial cavity, can result from either excessive formation or poor absorption of cerebrospinal fluid. Blockage of the flow of fluid in the spinal canal may result from a tumor, blood clot, or severance of the spinal cord. The pressure remains normal or decreases below the point of obstruction but increases above that point. Cell counts, bacterial smears, and cultures of samples of cerebrospinal fluid are done when an inflammatory process or infection of the meninges is suspected. Since the cerebrospinal fluid contains nutrient substances such as glucose, proteins, and sodium chloride, and also some waste products such as urea, it is believed to play a role in metabolism. The major constituents of cerebrospinal fluid are water, glucose, sodium chloride, and protein. Information about changes in their concentrations is helpful in diagnosis of brain diseases. Samples of cerebrospinal fluid may be obtained by lumbar puncture, in which a hollow needle is inserted between two lumbar vertebrae (below the lower end of the spinal cord), or into the cisterna cerebellomedullaris just below the occipital bone of the skull (cisternal puncture). Pressure of the cerebrospinal fluid is measured by a manometer attached to the end of the needle after it has been inserted. cer·e·bro·spi·nal flu·id (CSF),[TA]cerebrospinal fluidcerebrospinal fluidSpinal fluid Neurology A clear, colorless fluid that contains small quantities of glucose and protein, which surrounds the brain, spinal cord, ventricles, subarachnoid space, and the central canal of the spinal cord, provides nutrients, and acts as a shock absorber; CSF analysis is accomplished by lumbar puncture; WBCs or bacteria in the CSF indicate bacterial–septic meningitis. See Lumbar puncture.cer·e·bro·spi·nal flu·id(CSF) (ser'ĕ-brō-spī'năl flū'id) [TA] cerebrospinal fluidAbbreviation: CSFFormationThe fluid is formed by the choroid plexuses of the lateral and third ventricles. That of the lateral ventricles passes through the foramen of Monro to the third ventricle, and through the aqueduct of Sylvius to the fourth ventricle. There it may escape through the central foramen of Magendie or the lateral foramina of Luschke into the cisterna magna and to the cranial and spinal subarachnoid spaces. It is reabsorbed through the arachnoid villi into the blood in the cranial venous sinuses, and through the perineural lymph spaces of both the brain and the cord. See: illustration CharacteristicsThe fluid is normally watery, clear, colorless, and almost entirely free of cells. The initial pressure of spinal fluid in a side-lying adult is about 100 to 180 mm of water. On average, the total protein is about 15 to 50 mg/dL, and the concentration of glucose is about twothirds the concentration of glucose in the patient's serum. Its pH, which is rarely measured clinically, is slightly more acidic than the pH of blood. Its concentration and alkaline reserve are similar to those of blood. It does not clot on standing. Turbidity suggests an excessively high number of cells in the fluid, typically white blood cells in infections such as meningitis or red blood cells in intracerebral hemorrhage. CSF may appear red following a recent subarachnoid hemorrhage or when the lumbar puncture that obtained the CSF caused traumatic injury to the dura that surround the fluid. Centrifugation of the fluid can distinguish between these two sources of blood in the spinal fluid: the supernatant is usually stained yellow (xanthochromic) only when there has been a recent subarachnoid hemorrhage. Many conditions may cause increases in CSF total protein: infections, such as acute or chronic meningitis; multiple sclerosis (when oligoclonal protein bands are present); Guillain-Barré syndrome; and chronic medical conditions like cirrhosis and hypothyroidism (when diffuse hypergammaglobulinemia is present). The concentration of glucose in the CSF rises in uncontrolled diabetes mellitus and drops precipitously in meningitis, sarcoidosis, and some other illnesses. Malignant cells in the CSF, demonstrated after centrifugation or filtering, are hallmarks of carcinomatous meningitis. MicroorganismsThe CSF is normally sterile. Meningococci, streptococci, Haemophilus influenzae, Listeria monocytogenes, and gram-negative bacilli are recovered from the CSF only in cases of meningitis. Syphilitic meningitis is usually diagnosed with serological tests for the disease, such as the venereal disease research laboratory (VDRL) test, the rapid plasma reagin (RPR) test, or the fluorescent treponemal antibody test. Cryptococcal infection of the CSF may be demonstrated by India ink preparations, or by latex agglutination tests. Tuberculous meningitis may sometimes be diagnosed with Ziehl-Neelsen stains, but more often this is done with cultures. These last three infections (syphilis, cryptococcosis, and tuberculosis) are much more common in patients who have acquired immunodeficiency syndrome (AIDS) than in the general population. cerebrospinal fluidThe watery fluid that bathes the brain and spinal cord and also circulates within the ventricles of the brain and the central canal of the cord.cerebrospinal fluid (CSF)a solution secreted by the CHOROID PLEXUSES (one in the roof of each of the four brain VENTRICLES (2) in man) which fills the cavity of the brain and SPINAL CORD and the space between the CENTRAL NERVOUS SYSTEM and its ensheathing membrane. It contains most of the small molecules found in blood, e.g. salts and glucose, but little protein and few cells, and serves as a nutritive medium. In humans the total volume is about 100 cm3.Cerebrospinal fluid (CSF)cer·e·bro·spi·nal flu·id(CSF) (ser'ĕ-brō-spī'năl flū'id) [TA]cerebrospinal fluid
Synonyms for cerebrospinal fluid
|
|||
| 随便看 |
|
英语词典包含2567994条英英释义在线翻译词条，基本涵盖了全部常用单词的英英翻译及用法，是英语学习的有利工具。