ABSTRACT

Sense organs and sensory receptors detect information about the environment such as light, sound, smell, taste and touch and cause sensory transduction whereby cells convert extra-cellular signals into electrical signals (energy). Usually, the plasma membrane of a sensory receptor is stimulated to cause depolarization that will result in an action potential once the threshold limit has been exceeded. The sense organs are vital to vertebrates as they detect and provide information that enables these animals to make appropriate responses. The sense organs of vertebrates are complex in comparison to those of invertebrates and have contributed to the complex behaviors seen in vertebrates that also have a complex nervous system that is highly cephalized or shows a high degree of brain development. Since the anterior or superior end of bilaterally symmetrical animals moves through the environment first or is the highest from the ground depending on species, this end contains most of the sense organs. With evolution, the anterior or superior end of the nervous system become larger with more complex pathways to be able to process information received from the sense organs.