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.
When _____ reaches the ends of the axon, the neurotransmitter is released and diffuses to the muscle cell membrane to combine with receptors there Nerve impulse (action potential) The combining of the neurotransmitter with the muscle membrane receptors causes the membrane to become permeable to both sodium and potassium The greater influx of sodium ions results in _____ of the membrane.