Cigarette smoke contains over 4,000 chemicals, including 43 known cancer-causing (carcinogenic) compounds and 400 other toxins. These include nicotine, tar, and carbon monoxide, as well as formaldehyde, ammonia, hydrogen cyanide, arsenic, and DDT.
Involuntary muscles are muscles that are not controllable consciously, and instead contract due to unconscious impulses sent by the autonomic nervous system or certain specialized cells or hormones.Both smooth muscle and cardiac muscle can be classified as involuntary muscles.Smooth muscle is comprised of spindle-shaped cells that have no striations and is found in numerous locations throughout the human body. Cardiac muscle is striated rather than smooth, and is found only within the walls of the heart. beating heart is one of the best examples of an involuntary muscle. Contractions of cardiac muscles push blood through the four chambers of the human heart. The process of peristalsis, which pushes food through the esophagus and small intestine, is controlled by involuntary muscles.
Dictionary. Definition of involuntary muscle. a muscle that contracts without conscious control and found in walls of internal organs such as stomach and intestine and bladder and blood vessels (excluding the heart)Similar Words: smooth muscle Hyponyms: myometrium, musculus sphincter ani internus.efinition of involuntary muscle. a muscle that contracts without conscious control and found in walls of internal organs such as stomach and intestine and bladder and blood vessels (excluding the heart)Similar Words: smooth muscle Hyponyms: myometrium, musculus sphincter ani internus.