Dendritic spineA dendritic spine (or spine) is a small membrane protrusion from a neuron's dendrite that typically receives input from a single axon at the synapse. Dendritic spines serve as a storage site for synaptic strength and help transmit electrical signals to the neuron's cell body. Most spines have a bulbous head (the spine head), and a thin neck that connects the head of the spine to the shaft of the dendrite.
Growth coneA growth cone is a large actin-supported extension of a developing or regenerating neurite seeking its synaptic target. It is the growth cone that drives axon growth. Their existence was originally proposed by SpanishhistologistSantiago Ramón y Cajal based upon stationary images he observed under the microscope. He first described the growth cone based on fixed cells as "a concentration of protoplasm of conical form, endowed with amoeboid movements" (Cajal, 1890).NeuriteA neurite or neuronal process refers to any projection from the cell body of a neuron. This projection can be either an axon or a dendrite. The term is frequently used when speaking of immature or developing neurons, especially of cells in culture, because it can be difficult to tell axons from dendrites before differentiation is complete.
SynapseIn the nervous system, a synapse is a structure that allows a neuron to exchange (receive or send) signals with another cell in its immediate vicinity. Synapses can be classified as either chemical or electrical, depending on the mechanism of signal transmission between neurons. In the case of electrical synapses, neurons are coupled bidirectionally with each other through gap junctions and have a connected cytoplasmic milieu.
Neuromuscular junctionA neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuron and a muscle fiber. It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction. Muscles require innervation to function—and even just to maintain muscle tone, avoiding atrophy. In the neuromuscular system, nerves from the central nervous system and the peripheral nervous system are linked and work together with muscles.
NeuronPrimary cell of the nervous systemA neuron (American English), neurone (British English), or nerve cell, is a cell that is excitable, firing electric signals called action potentials. Neurons form neural networks in the nervous system, mainly in the central nervous system. Neurons receive and conduct impulses.
Synaptic pruningSynaptic pruning is the process of synapse elimination or weakening. Though it occurs throughout the lifespan of a mammal, the most active period of synaptic pruning in the development of the nervous system occurs between early childhood and the onset of puberty in many mammals, including humans. Pruning starts near the time of birth and continues into one's late 20s. During elimination of a synapse, the axon withdraws or dies off, and the dendrite decays and dies off.
Nervous systemIn biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensoryinformation by transmitting signals to and from different parts of its body. The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to such events. Nervous tissue first arose in wormlike organisms about 550 to 600 million years ago.
NeurotrophinNeurotrophins are a family of proteins that induce the survival, development, and function of neurons. They belong to a class of growth factors. Growth factors such as neurotrophins that promote the survival of neurons are known as neurotrophic factors. Neurotrophic factors are secreted by target tissue and act by preventing the associated neuron from initiating programmed cell death – allowing the neurons to survive.
Critical periodIn imprinting and developmental biology, a critical period is a maturational stage in the lifespan of an organism during which the nervous system is especially sensitive to certain environmental stimuli. If, for some reason, the organism does not receive the appropriate stimulus during this "critical period" to learn a given skill or trait, it may be difficult, ultimately less successful, or even impossible, to develop certain associated functions later in life.
LifeLife is the capacity in matter, formed of one or more units called cells, for processes such as cell signaling, homeostasis, metabolism, cell growth, adaptation, response to stimuli, and reproduction. All life eventually reaches a state of death. Many philosophical definitions of living systems have been proposed, such as self-organizing systems.Development of the nervous system in humansThe development of the nervous system in humans, or neural development, or neurodevelopment involves the studies of embryology, developmental biology, and neuroscience. These describe the cellular and molecular mechanisms by which the complex nervous system forms in humans, develops during prenatal development, and continues to develop postnatally.
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