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In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information 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]
The evolution of nervous systems dates back to the first development of nervous systems in animals (or metazoans). Neurons developed as specialized electrical signaling cells in multicellular animals, adapting the mechanism of action potentials present in motile single-celled and colonial eukaryotes .
The following are two lists of animals ordered by the size of their nervous system.The first list shows number of neurons in their entire nervous system. The second list shows the number of neurons in the structure that has been found to be representative of animal intelligence. [1]
The nerve net is the simplest form of a nervous system found in multicellular organisms. Unlike central nervous systems, where neurons are typically grouped together, neurons found in nerve nets are spread apart. This nervous system allows cnidarians to respond to physical contact. They can detect food and other chemicals in a rudimentary way.
The nervous system is the part of an animal that coordinates its actions by transmitting signals to and from different parts of its body. [7] 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, including the brainstem, and spinal cord.
The genomic content of the nervous system genes is the smallest known of any animal, and could represent the minimum genetic requirements for a functional nervous system. [48] The fact that portions of the nervous system feature directly fused neurons, without synapses, suggests that ctenophores might form a sister group to other metazoans ...
During early embryonic development of the vertebrate, the dorsal ectoderm becomes specified to give rise to the epidermis and the nervous system; a part of the dorsal ectoderm becomes specified to neural ectoderm to form the neural plate which gives rise to the nervous system. [3] [13] The conversion of undifferentiated ectoderm to ...
Biological organization spans several scales and are determined based different structures depending on what the system is. [1] Examples of biological systems at the macro scale are populations of organisms. On the organ and tissue scale in mammals and other animals, examples include the circulatory system, the respiratory system, and the ...