Autonomous Nervous System, Cardiovascular System, and Smooth Muscles
The autonomic nervous system, which regulates what we usually call our innards, is the part of the body linked with the brain. The autonomic nervous system regulates our vital functions without conscious control. We breathe, our heart beats, our stomach digests, and our bladder muscles contract. Further, we secrete saliva, insulin, and digestive enzymes. Our skeletal muscles are able to show vasodilatation and vasoconstriction without our conscious control of them. These functions are operating mainly on structures hidden from view. The autonomic system acts on smooth muscle (in the blood vessels and intestines, cardiac muscles and glands). The autonomic system also has afferent pathways, carrying signals from our innards to the brain and spinal cord.