Petal Petal Petals are modified leaves that surround the reproductive parts of flowers. They are often brightly colored or unusually shaped to attract pollinators. Together, all of the petals of a flower are called a corolla. Petals are usually accompanied by another set of special leaves called sepals, that collectively form the "calyx" and lie just beneath the corolla. The calyx and the corolla together make up the perianth. When the petals and sepals of a flower are difficult to distinguish, they are collectively called tepals. Examples of plants in which the term "tepal" is appropriate include genera such as "Aloe"
Calyx of Held causes an action potential to be triggered on the postsynaptic side – further encouraged by low internal sodium of the principal neurons. In the mature calyx, the AMPA receptors are concentrated on the principal neuron as to localize the transmission for greater action potential probability. Also note, the NMDA-type glutamate receptors contributions decrease after the onset of hearing. The mechanism behind synaptic vesicle endocytosis changes as the calyx becomes more mature. Calmodulin and calcineurin in their active form are required for vesicle endocytosis in an immature calyx; however, in the mature calyx neither calmodulin nor calcineurin are necessary. Rather, the