write about The Nervous System and Endocrine System in multi cellular animals
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The nervous system is the part of an animal that coordinates its actions by transmitting signals to and from different parts of its body. The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to such events.[1] Nervous tissue first arose in wormlike organisms about 550 to 600 million years ago. In vertebrates it consists of two main parts, the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord. The PNS consists mainly of nerves, which are enclosed bundles of the long fibers or axons, that connect the CNS to every other part of the body. Nerves that transmit signals from the brain are called motor or efferent nerves, while those nerves that transmit information from the body to the CNS are called sensory or afferent. Spinal nerves serve both functions and are called mixed nerves
The nervous system is the network of specialized cells, tissues, and organs in a multicellular animal that coordinates the body's interaction with the environment, including sensing internal and external stimuli, monitoring the organs, coordinating the activity of muscles, initiating actions, and regulating behavior. At the cellular level, the nervous system is defined by the presence of a special type of excitable cell called a neuron (or "nerve cell") that transmits impulses. All parts of the nervous system are made of nervous tissue, which contains the two main categories of cells: neurons and supporting glia cells. An example of an organ that is part of the nervous system is the brain, which serves as the center of the nervous system in all vertebrate and most invertebrate animals.