Nasal polyps grow in inflamed tissue of the nasal mucosa. The mucosa is a very wet layer that helps protect the inside of your nose and sinuses and humidifies the air you breathe. During an infection or allergy-induced irritation, the nasal mucosa becomes swollen and red, and it may produce fluid that drips out. With prolonged irritation, the mucosa may form a polyp.
Muscle action can be classified as being either voluntary or involuntary. Cardiac and smooth muscles contract without conscious thought and are termed involuntary, whereas the skeletal muscles contract upon command. Skeletal muscles in turn can be divided into fast and slow twitch fibers.
Slow twitch motor units are controlled by slow twitch nerves. In the laboratory you can take a nerve from a motor unit that supplies a slow twitch muscle fiber and replace it with one that supplies a fast twitch fiber and the slow twitch fiber will behave just like a fast twitch fiber! The reverse is also true.n the laboratory you can take a nerve from a motor unit that supplies a slow twitch muscle fiber and replace it with one that supplies a fast twitch fiber and the slow twitch fiber will behave just like a fast twitch fiber! The reverse is also true.