What Is a Neural Circuit? Introduction A single neuron can receive, process, and transmit signals, but most functions of the nervous system cannot be produced by one neuron alone. They emerge from groups of interconnected neurons working together. These connected groups are called neural circuits. Neural circuits allow the nervous system to transform sensory information…
What Are Neurotransmitter Receptors? Introduction Neurons communicate using chemical messengers such as glutamate, GABA, dopamine, serotonin, and acetylcholine. However, these messengers can affect a cell only when the cell has a receptor capable of recognizing them. Neural receptors convert chemical signals into electrical or biochemical responses. The receptor subtype—not just the neurotransmitter—helps determine how a…
What Is Excitation–Inhibition Balance in the Brain? Introduction The brain must remain active enough to process information but controlled enough to prevent activity from spreading without limit. It achieves this partly by coordinating excitatory signals, which tend to increase neuronal activity, with inhibitory signals, which tend to restrain or shape it. This coordination is called…
How Do Neurons Combine Excitatory and Inhibitory Signals? Introduction A neuron can receive thousands of signals from other cells. Some signals increase the likelihood that it will fire, while others reduce or regulate that likelihood. The neuron continuously combines these excitatory and inhibitory inputs before deciding whether to generate an action potential. This process is…
What Are Excitatory and Inhibitory Signals? Introduction Neurons constantly receive signals from other cells. Some signals make a neuron more likely to generate an action potential, while others make it less likely. These are called excitatory signals and inhibitory signals. The brain needs both types to transmit information while keeping neural activity controlled and organized….
What Is Myelin? Introduction Myelin is a specialized membrane that wraps around many axons in the nervous system. It acts as electrical insulation, helping nerve signals travel rapidly and reliably between the brain, spinal cord, peripheral nerves, muscles, and sensory organs. Damage to the myelin sheath can slow or block nerve-signal conduction and contribute to…
What Are Glial Cells? Types and Functions Introduction Neurons receive, process, and transmit information, but they cannot maintain the nervous system by themselves. They depend on several types of cells collectively known as glial cells. Glial cells regulate the chemical environment around neurons, form myelin, support synapses, participate in immune defense, guide nervous-system development, and…
What Is the Parasympathetic Nervous System? The parasympathetic nervous system helps the body perform routine maintenance functions such as digesting food, slowing the heart, producing saliva, emptying the bladder, and adjusting the eyes for near vision. It is often described as the “rest and digest” system. This phrase is useful, but incomplete: the parasympathetic nervous…
What Is the Sympathetic Nervous System? Introduction When you exercise, stand up quickly, enter a hot environment, or face a sudden threat, your body must adjust automatically. Your heart may beat faster, blood vessels change their diameter, and sweat production increases. Many of these responses are coordinated by the sympathetic nervous system, one division of…
