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Autoimmune diseases occur when the immune system destroys its own healthy tissues. When this occurs, white blood cells cannot distinguish between pathogens and normal cells.
ACTH levels are normally highest in the early morning (between 6 and 8 A.M.) and lowest in the evening (between 6 and 11 P.M.). Therefore, a doctor who suspects abnormal levels looks for low ACTH in the morning and high ACTH in the evening.
Human neurons are so small that they require a microscope in order to be seen. However, some neurons can be up to 3 feet long, such as those that extend from the spinal cord to the toes.
Though Candida and Aspergillus species are the most common fungal pathogens causing invasive fungal disease in the immunocompromised, infections due to previously uncommon hyaline and dematiaceous filamentous fungi are occurring more often today. Rare fungal infections, once accurately diagnosed, may require surgical debridement, immunotherapy, and newer antifungals used singly or in combination with older antifungals, on a case-by-case basis.
Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.