This week we talked about the nervous system. One of the responsibilities of the nervous system is to maintain the internal homeostasis of the human body. There are a few different structures that help to make up the nervous system. These structures include the brain, the spinal cord, nerves, ganglia, enteric plexuses and sensory receptors. The activities formed by the nervous system can be divided into three groups. These groups are... sensory function, integrative function and motor function. We talked a lot about different vocabulary that has to do with the nervous system. A neuron is the findamental cell type of the nervous sytem. A neuron has three parts. There is the cell body, and axon and dendrites. The cell body is where the nucleus is surrounded by cytoplasm. Dendrites look somewhat like little trees coming out from the cell body. Dendrites are the recieving part of the neuron. For the most part the are short, tapering, and have a lot of branches. An axon conducts inpulses from the cell body. The axon is long, thin and cylindrical projection that joins the the cell body at a cone shaped elevation . This elevation is called the axon hillock. The cytoplasm of an axon is called axoplasm. The axoplasm is surrounded by a plasma membrane called axolemma. Along the axon there are branches called axon collaterals that extend out. The axon and its collaterals are divided into many processes called axon terminals. We also talked a bit about neurontrasmitters. These are molecules within the axon terminals that are released in the synaptic cleft. This is in response to a neve impulse. They also change the the membran potential of the post synaptic neuron.
