synapse

(noun)

the junction between the terminal of a neuron and either another neuron or a muscle or gland cell, over which nerve impulses pass

Related Terms

Examples of synapse in the following topics:

  • Synaptic Plasticity

    • Synaptic plasticity is the strengthening or weakening of synapses over time in response to increases or decreases in their activity.
    • Plastic change also results from the alteration of the number of receptors located on a synapse.
    • The weakening and pruning of unused synapses trims unimportant connections, leaving only the salient connections strengthened by long-term potentiation.
    • LTP arises when a single synapse is repeatedly stimulated.
    • LTD occurs when few glutamate molecules bind to NMDA receptors at a synapse (due to a low firing rate of the presynaptic neuron).

  • Synaptic Transmission

    • In a chemical synapse, the pre and post synaptic membranes are separated by a synaptic cleft, a fluid filled space.
    • Neurotransmission at a chemical synapse begins with the arrival of an action potential at the presynaptic axon terminal.
    • Third, diffusion of the neurotransmitter as it moves away from the synapse.
    • Communication at chemical synapses requires release of neurotransmitters.

  • Sensory-Somatic Nervous System

    • Unlike the autonomic nervous system, which has two synapses between the CNS and the target organ, sensory and motor neurons have only one synapse: one ending of the neuron is at the organ and the other directly contacts a CNS neuron.
    • Acetylcholine is the main neurotransmitter released at these synapses.
    • Each sensory neuron has one projection with a sensory receptor ending in skin, muscle, or sensory organs, and another that synapses with a neuron in the dorsal spinal cord.

  • Autonomic Nervous System

    • Signaling to the target tissue usually involves two synapses.
    • A preganglionic neuron (originating in the CNS) synapses to a neuron in a ganglion that, in turn, synapses on the target organ .
    • This is both because one preganglionic neuron synapses on multiple postganglionic neurons, amplifying the effect of the original synapse, and because the adrenal gland also releases norepinephrine (and the closely-related hormone epinephrine) into the blood stream.
    • In the autonomic nervous system, a preganglionic neuron of the CNS synapses with a postganglionic neuron of the parasympathetic nervous system.

  • Neurons

    • Four major types of neurons transmit signals through the body via specialized structures such as dendrites, axons, and synapses.
    • Dendrites are tree-like structures that extend away from the cell body to receive messages from other neurons at specialized junctions called synapses.
    • The cell body contains a specialized structure, the axon hillock, that integrates signals from multiple synapses and serves as a junction between the cell body and an axon: a tube-like structure that propagates the integrated signal to specialized endings called axon terminals .
    • These terminals, in turn, synapse on other neurons, muscles, or target organs.

  • Spinal Cord

    • For example, the knee reflex that a doctor tests during a routine physical is controlled by a single synapse between a sensory neuron and a motor neuron.
    • While a reflex may only require the involvement of one or two synapses, synapses with interneurons in the spinal column transmit information to the brain to convey what happened (the knee jerked, or the hand was hot).

  • Glia

    • They provide nutrients and other substances to neurons, regulate the concentrations of ions and chemicals in the extracellular fluid, and provide structural support for synapses.
    • They have been shown, through calcium-imaging experiments, to become active in response to nerve activity, transmit calcium waves between astrocytes, and modulate the activity of surrounding synapses.

  • Forms of Signaling

    • One example of paracrine signaling is the transfer of signals across synapses between nerve cells.
    • The junction between nerve cells where signal transmission occurs is called a synapse.
    • The neurotransmitters are transported across the very small distances between nerve cells, which are called chemical synapses .

  • Natural Killer Cells

    • Granzymes are released along with the perforin in the immunological synapse.

  • Transduction of Sound

    • When the hairs bend, they release an excitatory neurotransmitter at a synapse with a sensory neuron, which then conducts action potentials to the central nervous system.
    • About 90 percent of the afferent neurons carry information from inner hair cells, with each hair cell synapsing with 10 or so neurons.