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Synaptic delay is the period of time for neurotransmitter chemicals released from the axon terminus of the sending neuron to cross the synaptic gap by diffusion and attach to matching receptors on the receiving neuron, initiating a reaction (either stimulatory or inhibitory) in that neuron.
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What causes the synaptic delay?
The cause of synaptic delay is attributed mainly to the time needed for the synaptic vesicles to release neurotransmitter into the synaptic cleft. While it can be considered a combination of binding to the presynaptic membrane (which is relatively a transient process) and subsequent exocytosis of the neurotransmitter, the main factor is release. Additionally, it does take a very short period of time for the neurotransmitter to diffuse across the synaptic cleft and bind to to its receptors on the post-synaptic membrane.
Which reflex shows the least synaptic delay?
human physiology
Is there any synaptic delay in communication from pre-synaptic neuron to post-synaptic neuron?
Yes, when speaking of a chemical synapse; but no, not so much, when speaking of an electrotonic (gap junction) synapse.There are two types of synapses in the nervous system: chemical synapses, and electrical synapses (also know as electrotonic synapses or gap junctions).Chemical synapses have a small gap between two neurons, called the synaptic cleft, about 30nm across. At this gap, the two neurons do not touch (except for small molecules projecting from each and sticking to one another so as to keep the neurons in place to maintain the synapse; they are called synaptic adhesion molecules); the two neurons do not exchange their interior cellular fluid, the cytosol, nor any ions or other solutes. On receipt of a neural impulse, the pre-synaptic neuron releases Neurotransmitter chemicals into the synaptic cleft, which then diffuse across the synaptic cleft to the post-synaptic neuron, where they fit into receptors there and cause ligand-gated ion pores to open in the post-synaptic neuron, allowing sodium ions into it, which is the beginning of the neural signal in that neuron. The release of the neurotransmitter, its diffusion across the gap, the opening of the ligand-gated ion pores, and the entry of sodium ions takes a comparative long time, with the result that the synaptic delay for a chemical synapse is approximately 2 ms.Electrical synapses have a much smaller gap between neurons, about 3.5nm, with pore structures spanning the gap, which allows ions in the pre-synaptic neuron to pass directly into the post-synaptic neuron. Since there is no need for the pre-synaptic neuron to release neurotransmitters, nor for them to diffuse across a comparatively large gap, nor to cause ligand-gated pores to open, the synaptic delay for an electrical synapse is shorter, approximately 0.2ms.However, the difference in synaptic delay between chemical and electrical synapses may be less for mammals than for cold-blooded animals.
Why is response time in a monosynaptic reflex much faster than response time in a polysynaptic reflex?
Transmission across a chemical synapse always involves a synaptic delay, but with only one synapse (a monosynaptic reflex), the delay between stimulus and response is minimized. In a polysynaptic reflex, the length of delay is proportional to the number of synapses involved.
What is synaptic potential?
synaptic potential
The are sack-like structures found inside the synaptic knob containing chemicals?
synaptic vesicles
What is the small space separating pre and post-synaptic neurons?
synaptic cleft (also known as "synaptic gap")
What causes calcium ions to enter the synaptic bulb?
The nerve signal arrives at a synaptic knob and causes calcium channels to open. This allows the calcium ions to enter the synaptic knob. Calcium ions entry into the synaptic knob triggers exocytosis of synaptic vesicles, which release acetylcholine into the synaptic cleft.
Is synaptic transmission always from pre to post synaptic?
Yes
What are synaptic gaps?
Synaptic gaps are the spaces between neurons.
What are the tiny sacs found within the terminal button which release chemicals into the synapse?
The tiny sacs in the synaptic knob are known as synaptic vessels. The synaptic vessels release chemicals into the bloodstream with each synapse.
How is synaptic potential associated with pain?
What is the role of synaptic potentials in the perception of pain? What kind of reaction might you expect if synaptic potentials were removed?
