Flu (influenza) viruses are divided into four broad categories: influenza A, B, C or D. Influenza A is the most common type. H1N1 flu is a subtype of influenza A.
Subtypes of influenza A are categorized based on two proteins on the surface of the virus, hemagglutinin (H) and neuraminidase (N). There are many H and N subtypes, and each one is numbered. All H and N flu subtypes are influenza A viruses.
Each influenza subtype has many different strains of influenza virus. Not all strains infect people. Subtypes of influenza A viruses currently found in people are strains of H1N1 and H3N2. Each year's flu vaccine includes varieties of both of these strains and influenza B.
i hope this helps. please mark brainliest if it does :)
When the stimulation of the motor neuron providing the impulse to the muscle fibers stops, the chemical reaction that causes the rearrangement of the muscle fibers' proteins is stopped.
Explanation:
This reverses the chemical processes in the muscle fibers and the muscle relaxes. hope this helps you :)
