1. Acetylcholine is the most common. Neurons that release it are called cholinergic. Cholinergic neurons include all preganglionic neurons of the autonomic nervous system, postganglionic neurons of the parasympathetic nervous system and some postganglionic neurons (sweat glands) of the sympathetic nervous system.cetylcholine is the most common. Neurons that release it are called cholinergic. Cholinergic neurons include all preganglionic neurons of the autonomic nervous system, postganglionic neurons of the parasympathetic nervous system and some postganglionic neurons (sweat glands) of the sympathetic nervous system.
Translocation is the movement of materials from leaves to other tissues throughout the plant. Plants produce carbohydrates (sugars) in their leaves by photosynthesis, but nonphotosynthetic parts of the plant also require carbohydrates and other organic and nonorganic materials.t is pressure, generated in the sieve elements and companion cells in source tissues. In leaves, sugar is synthesized in mesophyll cells (the middle layer of the leaf), and is then actively pumped into the phloem, using metabolic energy.
This causes water to move into the sieve-tube element by osmosis, creating pressure that pushes the sap down the tube. In sugar sinks, cells actively transport solutes out of the sieve-tube elements, producing the exactly opposite effect.Some plants, however, appear not to load phloem by active transport.his causes water to move into the sieve-tube element by osmosis, creating pressure that pushes the sap down the tube. In sugar sinks, cells actively transport solutes out of the sieve-tube elements, producing the exactly opposite effect.