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.
Norepinephrine Synthesis and Release. Norepinephrine (NE) is the primary neurotransmitter for postganglionic sympathetic adrenergic nerve s. It is synthesized inside the nerve axon, stored within vesicles, then released by the nerve when an action potential travels down the nerve.Below are the details for release and synthesis of NE: Dopamine is transported into vesicles then converted to norepinephrine (NE) by dopamine Î²-hydroxylase (DBH); transport into the vesicle can by blocked by the drug reserpine. 2  An action potential traveling down the axon depolarizes the membrane and causes calcium to enter the axon.