The “compactness” of a substance, defined as its mass per unit volume. In radiology, the term relates to the amount of radiation absorbed by the structure being X-rayed. Bone, which absorbs radiation well, appears white on X-ray film. A lung, which contains mostly air, absorbs little radiation and is dark on film. The same holds true in CT scanning and MRI. (See also specific gravity.)
The number of a given vector species present. It may be expressed in relative terms (e.g., the biting density in relation to the human host) or in absolute numbers (e.g., the number present in a room, cattle-shed or artificial shelter).... vector density
The compactness of bone tissue in relation to its volume. A decrease in bone density is a normal part of aging. However, in some people, excessive loss of density (see osteoporosis) can lead to fractures. Less commonly, an increase in bone density (see osteosclerosis) occurs in certain disorders (see osteopetrosis; Paget’s disease). Bone density can be measured by a technique known as densitometry, which uses low-dose X-rays.... bone density
(VLDL) a *lipoprotein that is the precursor of *low-density lipoprotein (LDL). Containing triglycerides and cholesterol, it is produced in the liver and circulates in the bloodstream, where its triglycerides are hydrolysed to free fatty acids by *lipoprotein lipase. The remaining lipoprotein becomes progressively denser and richer in cholesterol to form LDL.... very low-density lipoprotein
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