Sometimes you may have atrial flutter that develops into atrial fibrillation and vice versa. The risk factors for and the symptoms and causes of atrial flutter are similar to those of atrial fibrillation. For example, strokes are also a concern in someone with atrial flutter. As with atrial fibrillation, atrial flutter is usually not life-threatening when it's properly treated.
Nerves and Nerve Types. There three types of nerves in the central nervous system: motor neurons, sensory neurons and autonomic neurons. Motor nerves send impulses or signals from the brain and spinal cord to all of the muscles in the body.
A muscle cell is a special kind of cell that makes up an organism's muscle tissues. The muscles allow independent movement and regulate biological functions such as digestion and heartbeat. These cells are further specialized into distinct types based on their location and functions.