Influenza is caused when viruses of the family Orthomyxoviridae infect and kill the ciliated epithelial cells of the lungs.This leaves the gas exchange system open to secondary infection especially by pneumonia. Influenza can be fatal, especially in the very young the very old or people with chronic diseases.Influenza affects many mammals including humans, pigs, birds and chickens. There are three main strains influenza A, influenza B and influenza C, strain A being the most virulent. They are classified by their surface proteins.Examples are H1N1 and H3N2. The viruses mutate regularly with small changes leaving people with some immunity for the next wave of infectionMajor changes lead to epidemics or pandemics as people do not have the antibodies. Annual vaccines protect vulnerable groups against the virus, but there is no cure.
Influenza
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Specification: OCR Biology A (H020), AS-level, 4.1.1 Communicable diseases, disease prevention and the immune system. Topic: Communicable Diseases.
Key terms in this lesson
- organelle
- A membrane-bound structure within a cell with a specific structure suited to a specific function.
- mitochondrion
- An organelle with a double membrane, the inner one folded into cristae, that is the site of aerobic respiration and ATP production.
- prokaryotic cell
- A cell with no nucleus or membrane-bound organelles, found in bacteria.
- eukaryotic cell
- A cell with a nucleus and membrane-bound organelles, found in animals, plants, fungi and protoctists.
- gene
- A length of DNA that codes for a specific polypeptide.
More in Communicable Diseases
- Plant Diseases
- Tuberculosis
- Bacterial Meningitis
- HIV/AIDS
- Zoonotic Influenza
- Malaria
- Fungal Diseases
- Transmission of Pathogens
All 40 lessons in Communicable Diseases · All OCR AS-level Biology topics