What is an activity that is controlled by involuntary muscles?
Breathing, heart beating, blinking, swallowing… Smooth, or involuntary, muscle is made of fibers, but this type of muscle looks smooth, not striated. Generally, we can’t consciously control our smooth muscles; rather, they’re controlled by the nervous system automatically (which is why they are also called involuntary). Examples of smooth muscles are the walls of the stomach and intestines, which help break up food and move it through the digestive system. Smooth muscle is also found in the walls of blood vessels, where it squeezes the stream of blood flowing through the vessels to help maintain blood pressure. Smooth muscles take longer to contract than skeletal muscles do, but they can stay contracted for a long time because they don’t tire easily. Cardiac muscle is found in the heart. The walls of the heart’s chambers are composed almost entirely of muscle fibers. Cardiac muscle is also an involuntary type of muscle. Its rhythmic, powerful contractions force blood out of the heart
