Understanding Glial Cells and Neurons in the Nervous System

Glial Cells (Glia) are responsible for maintaining the structure; they act as functional reservoirs, specialized barriers, and provide immune defense. Neurons are the structural and functional units of the nervous system, specialized to receive, carry, and transmit electrochemical signals called nerve impulses. Soma or Body is the part where the cellular organelles and the nucleus, mitochondria, Golgi apparatus, and lysosomes are located. You can find the Nissl substance here. Axon drives action potentials from the cell body to the synaptic terminal; the cytoplasm of the axon is called axoplasm, and the surrounding membrane is known as axolemma. Dendrites are short extensions of the cytoplasm of the neuronal soma. Sodium-Potassium Pump: for every 3 sodium ions pumped out of the cell, 2 potassium ions are pumped in, corresponding to active transport, since the movement of ions requires energy expenditure in the form of ATP. Resting Potential: it is the result of the difference in concentration of certain ions between the inside and outside of the neuronal membrane. On the outer side of the membrane, the ions at higher concentration are Na⁺ and Ca²⁺. In the cytoplasm, there are K⁺ ions and a large number of negatively charged proteins. Neuronal Classification: Unipolar, bipolar, and multipolar. By Function: Sensory (afferent), motor (efferent), and association (interneurons). Voltage-Gated Channels and ligand-gated channels are essential for neuronal function. Action Potential: an electrochemical phenomenon caused by a change in the concentration of ions between the extracellular and intracellular environments. Depolarization and Repolarization: Increased permeability for sodium occurs when the so-called ionic channels, formed by proteins sensitive to voltage changes, open. Nervous Impulse: saltatory conduction is not continuous; it occurs at the Ranvier nodes, and the myelin sheath increases the speed of nerve impulse conduction. Synapses: the functional union between two neurons that allows the passage of nerve impulses from one nerve cell to another, which can be electrical or chemical.