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.
Phloem is a specialised tissue for food transport in higher plants. Phloem cells mainly transport sucrose along pressure gradients generated by osmosis. This phenomenon is called translocation. Phloem consists of two cell types, the sieve tubes and the intimately associated companion cells.ell types [edit]. 1  Parenchyma cells are living cells that have functions ranging from storage and support to photosynthesis and phloem loading (transfer cells). 2  Collenchyma cells â collenchyma cells are alive at maturity and have only a primary wall.