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 neurotransmitters are released into the space between the end of an axon and the tip of a dendrite from another neuron. This space is called a synapse (pronounced SIN-aps). The neurotransmitters travel the short distance through the synapse to the dendrite.