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.
Small openings on the underside of the leaf called stomata allow water to evaporate, whichmaintains the transpiration pull.4. Phloem transports the sugar produced during photosynthesis from the leaves to other partsof the plant where it is used to provide energy. 7. The steps involved in gas exchange in a leaf: 1. First, the water is carried up from the roots through the vascular tissues, through the stemto the leaves. 2. Carbon dioxide enters through the stomate (an opening in the epidermal tissue) in theleaf.