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Why transmission at chemical synapses is unidirectional and why is it significant?
ok why is it uni directional. because there are only the receptors for the neurotransmitter on the receiving dendrites and not on the terminating bud. this means that the sodium can only be absorbed into the next nerve cell/brain cell in the line. but sodium released in a nerve impulse that is not absorbed into the next cell is asimilated back into the original terminating bud for reuse.
as for why this is important. im speculating here but it means that the impulse can only go down the intended path and cannot go backwards in the chain.
*addition*
Uni-directionality is a function of the asymmetry of the synaptic cleft. Exocytosis of the neurotransmitter only occurs from the presynaptic terminal and is received at the postsynaptic receptors to cause initiation of the next impulse (Ca++ carried in dendrons). Although there are receptors on the presynaptic membrane, these are not depolarizing but inhibit further neurotransmitter release. Since the postsynaptic membrane does not release neurotransmitters and the receptors on the presynaptic membrane (auto-receptors) are not depolarising, the impulse is not back propagated.
Uni-directionality of the impulse also occurs due to the characteristic membrane potential changes caused by the action potential. The hyper-polarisation of the nerve section caused by K+ efflux (repolarising and then hyper-polarising the nerve as the channels are slow to close), allows for the resetting of Na+ channels. This period (and slightly beforehand when the Na+ channels inactivate) is called the refractory period. Not only does this stop another impulse passing along the neurone, but the impulse can not pass backwards either. NB: local currents in nerves will travel in both directions, but since the previous section of the nerve has inactivated Na+ channels and is undergoing a period of hyper-polarisation, the impulse will not be back propagated.
Uni-directionality is crucial to allow for the transmission of discrete impulses that can be interpreted by the brain as signals rather than an entire nerve depolarisation (which is not an impulse at all).
So:
Uni-directionality due to:
- asymmetry of cleft
- Na+ inactivation
- K+ efflux hyperpolarisation
Uni-directionality important because:
- allows for discrete impulses
What else can I help you with?
Cells in the nervous system communicate to each other across gaps called?
Cells in the nervous system communicate to each other across gaps called synapses. At these synapses, signals are passed between neurons using chemical messengers called neurotransmitters. This allows for the transmission of information throughout the nervous system.
What are specialized junctions between neurons called?
Specialized junctions between neurons are called synapses. Synapses allow neurons to communicate with each other by transmitting signals in the form of neurotransmitters. There are two main types of synapses: electrical synapses, where ions flow directly between neurons, and chemical synapses, where neurotransmitters are released to relay the signal.
What is an electrical synapse?
Chemical synapses are much slower to react to stimuli. However chemical synapses transmit a signal with constant strength or even a signal that get stronger. This is called "gain." Electrical synapses are faster but have no "gain," the signal gets weaker as it travels along the synapse to other neurons. Electrical synapses are only used for applications where a reflex must be extremely fast. They are simple and allow for synchronized action. A benefit of electrical synapses is they will transmit signals in both directions. Chemical synapses have many important advantages as well. They are more complex and vary their signal strengths. Their functions are influenced by chemical outputs in the nervous system. Chemical synapses are the most common type.
Where do neurons meet?
Neurons meet and communicate with each other at junctions called synapses. At these synapses, they release and receive chemical neurotransmitters to transmit signals from one neuron to another.
How do the different types of synapses, such as axodendritic, axosomatic, and axoaxonic, contribute to the communication between neurons in the nervous system?
Different types of synapses, like axodendritic, axosomatic, and axoaxonic, play specific roles in how neurons communicate in the nervous system. Axodendritic synapses occur between the axon terminal of one neuron and the dendrites of another, allowing for the transmission of signals. Axosomatic synapses connect the axon terminal to the cell body, influencing the neuron's activity. Axoaxonic synapses regulate the release of neurotransmitters at the axon terminal, modulating communication between neurons. Overall, these different types of synapses help facilitate the flow of information in the nervous system.
What kind of chemical is released at a synapses?
neurotransmitter (:
Cells in the nervous system communicate to each other across gaps called?
Cells in the nervous system communicate to each other across gaps called synapses. At these synapses, signals are passed between neurons using chemical messengers called neurotransmitters. This allows for the transmission of information throughout the nervous system.
How do synapses affect reaction time?
Synapses play a critical role in determining reaction time by transmitting electrical or chemical signals between neurons. The efficiency of synaptic transmission can impact the speed at which signals travel through the nervous system, affecting overall reaction time. Stronger or more efficient synapses can lead to faster response times, while weak or impaired synapses may result in slower reaction times.
How does the impulses get over the synapses?
Neurotransmitters. It's purely chemical.
Are gap junctions chemical synapses?
Gap junctions are connections between cells and some do pass ions from one cell to another cell. Some are chemical, some are electrical synapses ans some are direct connections.
What are specialized junctions between neurons called?
Specialized junctions between neurons are called synapses. Synapses allow neurons to communicate with each other by transmitting signals in the form of neurotransmitters. There are two main types of synapses: electrical synapses, where ions flow directly between neurons, and chemical synapses, where neurotransmitters are released to relay the signal.
What is an electrical synapse?
Chemical synapses are much slower to react to stimuli. However chemical synapses transmit a signal with constant strength or even a signal that get stronger. This is called "gain." Electrical synapses are faster but have no "gain," the signal gets weaker as it travels along the synapse to other neurons. Electrical synapses are only used for applications where a reflex must be extremely fast. They are simple and allow for synchronized action. A benefit of electrical synapses is they will transmit signals in both directions. Chemical synapses have many important advantages as well. They are more complex and vary their signal strengths. Their functions are influenced by chemical outputs in the nervous system. Chemical synapses are the most common type.
Transmission of nerve impulses across the synapses is brought about by the secretions of very low concentrations of the chemicals known as?
neurotransmitters
How do depressants slow down the transmission of nerve impulses?
they stop the signals travelling down the nerves by blokcing the synapses
What is the chemical messenger that crosses synapse?
The chemical used to send messages across synapses is acetylcholine or ACh.
Where are synapses located between in the brain?
Between the axon terminals and the dendrite for one, there lay the chemical synapse.
Where do neurons meet?
Neurons meet and communicate with each other at junctions called synapses. At these synapses, they release and receive chemical neurotransmitters to transmit signals from one neuron to another.
