| thoracic part of spinal cord | The part of the spinal cord which consists of the twelve thoracic segments of the spinal cord from which the twelve pairs of thoracic nerves originate. Synonym: pars thoracica medullae spinalis, segmenta medullae spinalis thoracica. (05 Mar 2000) |
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| lateral column of spinal cord | A slight protrusion of the gray matter of the spinal cord into the lateral funiculus of either side, especially marked in the thoracic region where it encloses preganglionic motor neurons of the sympathetic division of the autonomic nervous system; it corresponds to the lateral horn appearing in transverse sections of the spinal cord. See: gray columns. Synonym: columna lateralis, lateral column of spinal cord. (05 Mar 2000) |
| lateral funiculus of spinal cord | The lateral white column of the spinal cord between the lines of exit and entrance of the anterior and posterior nerve roots. Synonym: funiculus lateralis, anterolateral column of spinal cord, lateral funiculus of spinal cord. (05 Mar 2000) |
| lumbar enlargement of spinal cord | A spindle-shaped swelling of the spinal cord beginning at the level of the tenth thoracic vertebra and tapering into the medullary cone, with maximum thickness opposite the last thoracic vertebra, consequential to the innervation of the lower limb. Synonym: intumescentia lumbalis, lumbar enlargement of spinal cord. (05 Mar 2000) |
| lumbar part of spinal cord | Portion of spinal cord which consists of the five lumbar segments (L1-L5) and from which five pairs of lumbar spinal nerves originate; in the adult it is located in the T10-L1 portion of the vertebral canal, and is enlarged relative to other parts of the cord due to its involvement in innervation of the lower limb. (05 Mar 2000) |
| lumbar segments of spinal cord | The five lumbar segments of the spinal cord which give rise to the five pairs of lumbar spinal nerves and constitute the lumbar part of the spinal cord. Synonym: segmenta medullae spinalis lumbaria. (05 Mar 2000) |
| ACE level | <investigation> This is a blood test which measures the concentration of angiotensin-converting enzyme (ACE) in the bloodstream. Elevations in angiotensin-converting enzyme are seen sarcoidosis, histoplasmosis, alcoholic cirrhosis, asbestosis, berylliosis, diabetes, Hodgkin's disease, hyperthyroidism, amyloidosis, primary biliary cirrhosis, idiopathic pulmonary fibrosis, pulmonary embolism, scleroderma, silicosis, tuberculosis, Gaucher's disease and leprosy. The normal values are 18 to 67 U/ml over 20 years of age (people under 20 have higher levels). (15 Jan 1998) |
| acoustic reference level | The biological reference level for sound measurements. When the term decibel is used to indicate the noise level, a reference quantity is implied; this reference value is usually expressed as a sound pressure of 20 micronewtons per square meter. The reference level is referred to as 0 decibels, the baseline of the scale of noise level's; this baseline is considered the weakest sound that can be heard by a person with very good hearing in an extremely quiet location. Other equivalent reference level's still being used include 0.0002 microbar and 0.0002 dyne per square centimeter. (05 Mar 2000) |
| background level | The average amount of a substance present in the environment. Originally referring to naturally occurring phenomena. Used in toxic substance monitoring. (05 Dec 1998) |
| blood porphyrin level | A test which is used to measure red blood cell porphyrin levels. Porphyrins are pigments found in both animal and plant life. This test is useful in evaluating any number of porphyrin disorders (involving the various porphyrins) of red blood cells. Increased levels of coproporphyrins can indicate congenital erythropoietic porphyria or sideroblastic anaemia. Increased protoporphyrins may be seen in infection, thalassaemia, sideroblastic anaemia, iron deficient anaemia, increased erythropoiesis and lead poisoning. Increased uroporphyrins may indicate congenital erythropoietic porphyria or erythropoietic protoporphyria. (27 Sep 1997) |
| carbon dioxide blood level | A measure of the bicarbonate level in the blood based on a venipuncture specimen. The serum carbon dioxide is one of the normally reported values in the electrolytes profile. Lower levels of carbon dioxide indicate an acidosis. The normal level is 20 to 29 mEq/L. Lower than normal levels can indicate diabetic ketoacidosis, lactic acidosis, alcoholic ketoacidosis, kidney disease, renal failure, diarrhoea, Addison's disease, ethylene glycol poisoning or methanol poisoning. Greater than normal levels can be seen with excessive vomiting, hyperaldosteronism and Cushing's syndrome. (27 Sep 1997) |
| vasopressin level | This test measures the amount of ADH in the serum. It is used to detect disorders that may affect the level of ADH in the serum. Normal values are: 0 to 4.7 pg/ml. Elevated ADH levels can indicate a CNS infection, fluid imbalance, CNS tumour, SIADH or acute porphyria. Low levels can indicate: diabetes insipidus or damage to the pituitary gland. (27 Sep 1997) |
| maximum permissible exposure level | The highest level of exposure to a substance, usually noxious, in the environment or during diagnostic and therapeutic procedures, that a body can tolerate without injury. (12 Dec 1998) |
| mean sea level | <marine biology> A tidal datum: the arithmetic mean of hourly water elevations observed over a specific 19-year cycle. Points on land can be referenced to a mean sea level, in which case the datum assumes zero elevation. (09 Oct 1997) |
| gray level also gray value | <microscopy> The brightness of pixels in a digitised video image, commonly expressed in integers ranging from 0 (black) to 255 (white) for an 8-bit digital signal. (05 Aug 1998) |