Nervous System

As all part of the system is significant in building up and maintaining our bodies, the nervous system is the one assisting the other parts of the body to perform their functions/task. The nervous system or known as the body's control center is often well known for the connection with the brain along with the spinal cord. That's why doctors say that we have to keep standing and sitting straight or else our spine won't be working that well. It's because the spine holds and protects the spinal cord which is responsible for the neurons, dendrites, and axons to do their tasks such as sending and receiving signals from the skin to the brain. Nervous system is divided into two types. First is the central nervous system consisting of the brain and spinal cord and the peripheral nervous sytem which cmposes of nervous outside of the brain and spinal cord. Peripheral nervous system has two types one is somatic and the other is autonomic. Somatic is the voluntary nerves such as the skeletal muscles while autonomic is the other way around such as smooth, cardiac muscles and glands. Autonomic has two branches. One is parasympathetic and the other is sympathetic. Parasympathetic is for maintenance and sympathetic is for the alert system.
The nervous system does not only compose of "vein-and-artery-like" structures, but it has its own tissue called the nervous tissue. This is the part where neuroglia and neurons came. Neuroglia has several functions and has four types of CNS cells. Astrocytes for metabolic and structural support, microglia for removal of debris, oligodendrocytes for lipid insulation (myelin), & ependymal cells for covering and lining of cavitites. Neurons, on the other hand, has two types of PNS cells. Schwann cells produce myelin and satellite cells support other different kinds of cells. Inside a neuron is made up of dendrites that receives information from the environment and the axon that sends signals to other cells. Note that synapses is a term that has the axon terminal and a receiving cell after sending signals.
Impulse conduction is the speed of how nerves send and receive signals to other cells, to the spinal cord, and to the brain. It can be determined through the presence of myelin and the diameter of the axon. Myelin is the lipid insulation produced by oligodendrocytes which is in the myelin sheath building up nodes of Ranvier similar to the muscles.
In the concept of chemical synapses, there are different types of cells. One is the polarized cells which has more negative charges, depolarized having positive charges, hyperpolarized which has twice the negative charges than the polarized and repolarization for converting negative to positive charge and vice versa.