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.
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.
The monosynaptic reflex, such as the knee-jerk reflex, has the least synaptic delay because it involves only one synapse between sensory and motor neurons in the spinal cord. This direct connection allows for a rapid response to a stimulus.
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.
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.
The sack-like structures inside the synaptic knob containing chemicals are called synaptic vesicles. These vesicles store and release neurotransmitters, which are chemical messengers that transmit signals between neurons. When an action potential reaches the synaptic knob, it triggers the release of neurotransmitters from the synaptic vesicles into the synaptic cleft.
The small space separating pre and post-synaptic neurons is called the synaptic cleft. This cleft allows for the transmission of chemical signals, known as neurotransmitters, from the pre-synaptic neuron to the post-synaptic neuron to occur. The neurotransmitters are released by the pre-synaptic neuron and bind to receptors on the post-synaptic neuron to transmit the signal.
Yes
Synaptic gaps are the spaces between neurons.
synaptic cleft, where neurotransmitters are released by the synaptic terminal and bind to receptors on the muscle fiber to trigger a muscle contraction.
Synaptic - software - was created on 2001-11-13.
Calcium ions enter the presynaptic neuron resulting in the release of neurotransmitter from the per-synaptic membrane. The neurotransmitter diffuses across the synaptic cleft, fusing with the receptors of the post-synaptic membrane. This changes the sodium channels to open and sodium ions will to flow into the post-synaptic neuron, depolarizing the post-synaptic membrane. This initiates an action potential. After the post-synaptic neuron has been affected, the neurotransmitter is removed by a type of enzyme called cholinesterase. The inactivated neurotransmitter then returns to the pre-synaptic neuron.
The word synaptic is an adjective which means, pertaining to the synapses. So, I could describe dopamine as a chemical that has a synaptic function, as a neurotransmitter.