The Nervous System and Nervous Tissue

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 …

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 …

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 …

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

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 …