In normal individuals, there is a constant production of ketone bodies by the liver and their utilization by extrahepatic tissues. The concentration of ketone bodies in blood is maintained around 1 mg/dl. Their excretion in urine is very low and undetectable by routine urine tests (Rothera's test).
A: Examples of involuntary muscles, also known as smooth muscles, are the muscles of the urogenital tract, digestive tract, circulatory system and respiratory tract. Involuntary muscles are not controlled by the organism's will. Their actions are automatic and facilitated by the autonomic nervous system.
Cardiac muscle, found in the walls of the heart, is also under control of the autonomic nervous system, thus involuntary. The cardiac muscle cell is striated, like skeletal muscle. The cardiac muscle cell is rectangular in shape. The contraction of cardiac muscle is involuntary, strong, and rhythmical.