A cataract is a clouding of the lens in the eye that affects vision. Most cataracts are related to aging. Cataracts are very common in older people. By age 80, more than half of all Americans either have a cataract or have had cataract surgery.
Acetylcholine. Acetylcholine (ACh) is the transmitter released by the preganglionic nerve terminals of both the sympathetic and the parasympathetic divisions (Fig 6.2). The synapse at those sites utilizes a nicotinic receptor similar in structure to the receptor at the neuromuscular junction.
The neurotransmitter released from the varicosity has a considerably longer distance to travel than the acetylcholine released at an NMJ does. In addition, the neurotransmitter can bind to any one of the nearby smooth muscle cells, a flexibility not found in the NMJ. The chemicals that influence smooth muscle cells: As you'll recall, there is only one neurotransmitter released at the neuromuscular junction - acetylcholine.