False
Acetylcholine
It varies: In the somatic system (skeletal muscle) and parasympathetic branch of the autonomous nervous system (smooth & cardiac muscle) it is usually acetylcholine. In the sympathetic branch of the autonomous nervous system (smooth & cardiac muscle) it is usually norepinephrine (also called noradrenaline). There are exceptions, but this is the general rule.
specific cardiac and smooth muscle fibers
Breaking down acetylcholine can lead to muscle relaxation because acetylcholine is a neurotransmitter that stimulates muscle contraction. When acetylcholine is broken down, the signal for muscle contraction is reduced, resulting in muscle relaxation.
cardiac
acetylcholine (ACh)
Acetylcholine is the excitatory neurotransmitter released by neurons innervating skeletal muscles. Acetylcholine release stimulates muscle contraction by acting at the nicotinic-acetylcholine receptor on the surface of the muscle cell.
Acetylcholine is the primary chemical transmitter released at the neuromuscular junction. It binds to acetylcholine receptors on the muscle cell membrane, leading to muscle contraction.
Smooth cardiac muscle.
cardiac muscle cells are joined by intercalated disks.
Cardiac muscle is involuntary striated muscle. The cells of cardiac muscle have only one nucleus. The layer of the heart that contains cardiac muscle is called the myocardium.
Acetylcholine is the chemical that transmits signals across the neuromuscular junction. It binds to receptors on the muscle cell membrane, leading to muscle contraction.