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Crash Course Biology- the nervous systemIn this video, YouTube video blogger Hank Green gives an informative, yet interesting lecture on what a model nervous system is generally like. |
The brain is considered to be the center of the nervous system, as it controls all nervous processes, as well as interpreting sensory information- this is its main purpose in most organisms.
This is a neuron. Sensory neurons relay information from sense organs, motor neurons carry impulses to muscles and glands, and inter-neurons transmit impulses between sensory and motor neurons. A typical neuron consists of dendrites (fibers that receive stimuli and conduct them inward), a cell body (a nucleated body that receives input from dendrites), and an axon (a fibre that conducts the nerve impulse from the cell body outward to the axon terminals).
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The nervous systemThe nervous system is highly important to all organisms and is responsible for almost all bodily functions. Nervous systems contain networks of specialized cells. These specialized cells are called neurons. Neurons coordinate actions of an organism and send signals between parts of the body. In the majority of organisms, there are two parts of the nervous system- these are the central and peripheral. The central nervous system (CNS) often contains the brain, spinal cord, and retina. The peripheral nervous system (PNS) usually contains sensory neurons and clusters of neurons called ganglia. There are also nerves which connect the PNS to the CNS, allowing for a more centralized control of the organism's bodily functions. There is also a third portion of the nervous system, called enteric nervous system- this is a subsystem of the PNS, and when alone, can carry out all of the functions of the CNS and PNS combined.
Nerves send signals through tiny, thin fibers called axons. This causes chemicals to be released at junctions called synapses. A cell that receives some of these chemicals from synapses is likely to be changed or modulated. Another kind of neuron- a sensory neuron, will be caused by some form of external physical stimuli. These neurons inform the CNS of the physical condition of the body. Motor neurons are usually located in the CNS. They connect the CNS to structures such as muscles. There are more central neurons than any other type of neuron in the body. The interaction of these types of nerves result in the processing of sensory information. Aside from all these kinds of neurons, the nervous system also contains other specialized cells called glial cells. These provide both structural and metabolic support |