The nervous system is the primary control and communication center of the body. The nervous system can be divided into two major categories—the ...

The nervous system senses, integrates, and responds to various stimuli. Based on bodily control, the central nervous system cannot be divided ...

The nervous system has three main functions: sensation, integration, and motor output. Sensory functions detect and process stimuli from external and ...

Neurons, excitable nervous system cells, generally consist of three main parts: the cell body, the dendrites, and the axon. The cell body, also known as ...

The axon is a long, thin extended portion of the neuron that carries impulses from its cell body toward the effector cell. Axoplasm, the axon's ...

Neurons can be categorized either by their structure or their function. Structurally, neurons are classified by the number of processes emerging from the ...

Glial cells or neuroglia are non-neuronal cells in the nervous system that outnumber neurons. These include astrocytes, oligodendrocytes, microglia, and ...

Myelin is a protective, multilayered covering around axons, composed of lipids and proteins, that provides electrical insulation. In the PNS, individual ...

An electrochemical gradient is a fundamental concept in biology and chemistry. It regulates the movement of ions across cell membranes. This movement is ...

Ligand-gated ion channels are transmembrane proteins with a channel for ions to pass through and a binding site for a ligand. The channel opens only when ...

Voltage-gated ion channels are transmembrane proteins that open and close in response to changes in the membrane potential. They are present on the ...

Mechanically-gated ion channels are proteins found in eukaryotic and prokaryotic cell membranes that open in response to mechanical stress. Tension, ...

The relative difference in electrical charge, or voltage, between the inside and the outside of a cell membrane, is called the membrane potential. It is ...

The resting membrane potential of a neuron (-70mV) is sustained due to the selective ion permeability of the membrane. At the resting potential, the ...

The graded potential is a short-lived, localized change in the membrane potential of a neuron. A graded potential occurs in response to a stimulus, ...

Neurons communicate by firing action potentials—the electrochemical signal that is propagated along the axon. The signal results in the release of ...

An action potential has three main phases: depolarization, repolarization, and hyperpolarization. The depolarizing phase begins after a graded potential ...

The Propagation of an action potential is the process by which a nerve impulse is transmitted along the axon. It is a self-propagating process; once ...

Synapse is a region where communication occurs between two neurons or a neuron and its effector cell. The neuron that carries the impulse toward the ...

Chemical synapses are specialized sites between two neurons or between a neuron and a non-neuronal cell like a muscle, glandular or sensory cell. Because ...

Neurotransmitters play a crucial role in the communication between neurons in the autonomic nervous system. Neurons in the autonomic nervous system can be ...

Postsynaptic potential or PSP refers to a change in the electrical potential of a postsynaptic membrane when neurotransmitters released by presynaptic ...

The integration of synaptic events involves the summation of multiple graded potentials, such as excitatory and inhibitory postsynaptic potentials, at the ...

In the central nervous system, billions of interconnected neurons are organized into specialized functional groups called neuronal pools. Within each ...

In the CNS, neurogenesis, the birth of new neurons from stem cells, is limited to the hippocampus in adults. In other regions of the brain and spinal ...

Nervous tissue disorders are caused by several factors. Homeostatic imbalances include cerebral hypoxia  — or reduced oxygen supply to the ...