Which on is correct and why??
nervous system is responsible for sensing the external and internal environments of an organism, and for inducing muscle movement. Human sensation is achieved through the stimulation of specialized neurons, organized into five different modalities—touch, balance, taste, smell, hearing, and vision. The touch modality includes pressure, vibration, temperature, pain, and itch. Some animals are also able to sense magnetism and electric fields. Modality, timing, intensity, and location of the stimulus are the four features that allow the brain to identify a unique sensation.
The neurons specialized to detect sensation are also called receptors because they are designed to receive information from the environment. Each receptor responds only to a stimulus that falls within a defined region, called its receptive field. The size of the stimulus can affect the number of receptors that respond, and the strength of the stimulus can affect how much they respond. For example, when a cat sits on your lap, a large population of receptors responds to the cat's weight, warmth, claws, and the vibrations from its purring.
Transduction refers to the transfer of environmental energy into a biological signal signifying that energy. Sensory receptors either transduce their respective stimuli directly, in the form of an action potential —the electrochemical communication between neurons—or they chemically communicate the transduction to a neuron . Neurons collect information at their dendrites , a long, branched process that grows out of the cell body. Information travels through the cell body, and then reaches the axon , another long process designed to transfer information by apposing, or synapsing on, another neuron's dendrites. In some receptors, the axon is branched, and is specialized for both initializing and transmitting action potentials.
ans would have none of their five senses if they did not also have a vast, branching network of nerves. These nerves take all of the coded messages to the brain, which translates or interprets them. The brain tells a person exactly what he or she is sensing. As a result, people do not really see with the sense organs called the eyes, for it is the brain that interprets the signals the eyes are sending. The brain tells a person that he or she is seeing a beautiful rainbow and not a dangerous fire. The role of the sense organs then is only to gather the information. Understanding that information is left to the brain.