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Notes On Brain And Brains Essay

Decent Essays

1. Brain cells and brains evolved pretty recently – about 250 million years ago, compared to the appearance of the first life-forms to arise.
• First evolved neurons and muscles to assist animals with movement.
• Nerve net – a connection of neurons that receive sensory information and send signals to other neurons that are involved in muscle movement.
• The first bilateral symmetry was described in flatworms, the nervous system on one side is almost identical to the other side, the human nervous system is arranged the same way.
• Segmentation, first observed in earthworms, whose bodies consist of several repeating segments, just like a human spinal cord.
• Ganglia. The first brain-like structure (a collection of neurons that function somewhat like brain) was found in clams, octopuses, snails, and insects.
• Spinal cord connects our brain and all the body parts senses. Was first found in highly evolved chordates.
• Brain. Amphibians, reptiles, birds, and mammals share this unique part of our central nervous system, but the human brain appears to be the largest relative to body size.
It is believed that our ancestors’ brains evolved from changing their life-styles: having an upright posture, constructing and using tools, and developing language.
2. The human brain and a spinal cord make up the central nervous system (CNS), which is responsible for mediating our behavior; it processes the afferent sensory information carried by the peripheral nervous system (PNS) – all

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