ANATOMY

Detailed explanation-1: -Influenza is caused by infection of the respiratory tract with influenza viruses, RNA viruses of the Orthomyxovirus genus.

Detailed explanation-2: -Influenza viruses are members of the family Orthomyxoviridae. This family represents enveloped viruses the genome of which consists of segmented negative-sense single-strand RNA segments.

Detailed explanation-3: -Pathogenesis. Following respiratory transmission, the virus attaches to and penetrates respiratory epithelial cells in the trachea and bronchi. Viral replication occurs, which results in the destruction of the host cell. Regeneration of epithelium takes about 3 to 4 weeks.

Detailed explanation-4: -Influenza viruses are significant human respiratory pathogens that cause both seasonal, endemic infections and periodic, unpredictable pandemics.

Detailed explanation-5: -Flu is caused by a virus that is spread from person to person. It causes seasonal epidemics each year.