Nervous Systems, Function and Survival

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Evolution is a process of gradual change over time in both body and corresponding behaviour (Open University Glossary, 2013). The evolution of animals’ and humans’ nervous systems is a necessary process to maximise the chances of survival. Neuronal and behavioural changes are closely linked to the environment surrounding animals and humans, as well as to their lifestyles. This essay will present some evidence that the nervous system of animals and humans have evolved as to maximize survival, by looking at specific elements of the nervous system on a cellular level, within the brain regions, through functioning pathways, systems and finally, behaviour.

First, what is the nervous system? For animals as for humans, the nervous system is a functional subdivision of the body. Its main function is to transmit and process information. The nervous system is involved in survival on many levels. Looking at the nervous system on a cellular level can offer some evidence of this. The nervous system possesses three main cell types, one of which being the neurons. These are formed of different elements, the axon, cell body and dendrites. Axons play an important part in the fast reaction for survival. The wider the axon, the faster it will conduct the action potentials. For example, the squid carries a particular neuron involved in the escape response from danger. The axon from this specific neuron has quite a wide diameter, which makes it conduct action potentials faster. Therefore, if the squid can react faster, then he might have more chance to escape from danger. The squid then possesses an evolutionary advantage that helps him to escape quickly from danger. Some types of animals have evolutionary advantages because of the complexity of their neuronal connections, and because of how the communication takes place. Nerve nets and sensory neurons are an example of this, and can be found in a multicellular animal such as a jelly fish. The simplicity of the nerve net offers a...
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