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.
Muscle tissues. There are three major types of muscle cells. The striated or skeletal muscle is under voluntary control and is the major effector organ of our bodies. It and the glands (endocrine and exocrine) carry out all the commands of the nervous and endocrine (communication) systems.onnective tissue: blood (red cells and white cells) Muscle tissues There are three major types of muscle cells. The striated or skeletal muscle is under voluntary control and is the major effector organ of our bodies.