A number on a scale for rating the degree of protection provided by sunscreens. SPF stands for Sun Protection Factor.
SPF numbers on a package can range from as low as 2 to as high as 100. These numbers refer to the product’s ability to screen or block out the sun’s burning rays. It is a common mistake to assume that the duration of effectiveness of a sunscreen can be calculated simply by multiplying the SPF by the length of time it takes for him or her to suffer a burn without sunscreen, because the amount of sun exposure a person receives is dependent upon more than just the length of time spent in the sun. The amount of sun exposure depends upon a number of factors including the length of exposure, time of day, geographic location, and weather conditions.
1. Shaped like a wedge. 2. Relating to the sphenoid bone (which is wedge-shaped).
- Sphenoid bone
A prominent, irregular, wedge-shaped bone at the base of the skull. The sphenoid bone has been called the ‘keystone’ of the cranial floor because it is in contact with all of the other cranial bones.
- Sphenopalatine neuralgia
Characterized by the absence of sustained periods of remission, chronic cluster headache may start with no past history of cluster headaches, or it may emerge several years after the patient has experienced an episodic pattern of cluster headaches. The episodic and acute forms of cluster headache may transform into one another, so it seems most […]
- Spherocytosis, hereditary (HS)
50 chance to have hereditary spherocytosis. The treatment of hereditary 0spherocytosis is to remove the spleen (splenectomy). Although the red cell defect persists, the breakup of the red cells (hemolysis) ceases. Splenectomy, however, is a hazard in young children. Young children without a spleen are at increased risk for overwhelming sepsis (bloodstream infection), particularly with […]
- Sphingomyelin lipoidosis
the classical infantile form (type A), the visceral (organ) form (type B), the subacute or juvenile form (type C), the Nova Scotian variant (type D), and the adult form (type E). The disease is named for the German physicians Albert Niemann (1880-1921) and Ludwig Pick (1868-1944). Other names for the disease include sphingomyelinase deficiency.