Neuroscience: Action Potentials & Synapses

Action potentials are small identical electrical changes that propagate along a neuron, allowing communication within the nervous system.

Action potentials propagate in one direction due to the refractory period, which prevents immediate reactivation of previously activated segments of the axon.

Neuroglia provide support and protection for neurons, while the myelin sheath insulates axons and enhances the speed of action potential propagation.

<p>Specialized sensory cells detect stimuli and convert them into electrical signals, which are transmitted across synapses to communicate with other neurons.</p> Signup and view all the answers

<p>Synaptic transmission involves the release of neurotransmitters from the presynaptic neuron, which bind to receptors on the postsynaptic neuron, triggering a response.</p> Signup and view all the answers

<p>Synapses connect neurons to form circuits, enabling complex information processing and communication within the nervous system.</p> Signup and view all the answers

<p>Local anesthetics block sodium channels to prevent nerve signal transmission, while neurotoxins disrupt neurotransmitter release or function at synapses.</p> Signup and view all the answers

<p>Diffusion allows neurotransmitters to travel across the synaptic cleft to bind with receptors on the postsynaptic neuron, facilitating signal continuation.</p> Signup and view all the answers

<p>Neurotransmitters are removed from the synapse through degradation by membrane-bound enzymes, reuptake into the presynaptic cell, or diffusion out of the synapse. This removal is crucial for terminating the signal and preventing continuous stimulation of the target cell.</p> Signup and view all the answers

<p>Drugs that block enzymes responsible for degrading neurotransmitters can lead to increased neurotransmitter levels in the synapse. This sustained elevation enhances nerve transmission, potentially alleviating symptoms of depression.</p> Signup and view all the answers

<p>Blocking the reuptake of neurotransmitters results in prolonged neurotransmitter presence in the synapse, enhancing synaptic transmission. A potential drug example is Selective Serotonin Reuptake Inhibitors (SSRIs).</p> Signup and view all the answers

<p>Ca2+ ions are crucial as their influx through voltage-gated channels triggers the release of neurotransmitters. This release facilitates communication between neurons across the synapse.</p> Signup and view all the answers

<p>Failure to adequately remove neurotransmitters can lead to prolonged signaling, resulting in disorders such as clinical depression or anxiety. This dysfunction can disrupt normal brain function and emotional regulation.</p> Signup and view all the answers

<p>No new action potentials are generated.</p> Signup and view all the answers

<p>The myelin sheath increases the speed of action potential propagation by insulating the axon.</p> Signup and view all the answers

<p>They propagate in one direction due to the inactivation of sodium channels behind the action potential, preventing backward flow.</p> Signup and view all the answers

<p>Local anesthetics block voltage-gated Na+ channels, preventing the initiation and propagation of action potentials.</p> Signup and view all the answers

<p>When the stimulus stops, the graded potential at the axon hillock can fall below -55 mV, leading to no action potentials.</p> Signup and view all the answers

<p>Synapses allow neurons to communicate and transmit signals, enabling complex neuronal circuits and processing.</p> Signup and view all the answers

<p>Neurotoxins can block or alter the function of ion channels, leading to disrupted action potentials.</p> Signup and view all the answers

<p>Synaptic transmission involves the release of neurotransmitters from presynaptic neurons, which bind to receptors on postsynaptic neurons.</p> Signup and view all the answers

<p>More synapses allow for increased complexity and integration of signals, enhancing the processing capability of neuronal circuits.</p> Signup and view all the answers

<p>Decreased sodium ions would impair action potential generation and transmission, leading to reduced neuronal activity.</p> Signup and view all the answers

<p>The graded potential at the axon hillock remains high, leading to the repeated generation of action potentials.</p> Signup and view all the answers

<p>Action potentials cease when the graded potential falls below -55 mV.</p> Signup and view all the answers

<p>Action potentials are generated rapidly because the sites are very close together, reducing the distances for signal propagation.</p> Signup and view all the answers

<p>When the stimulus is no longer present, no new action potentials are generated due to the drop in graded potential.</p> Signup and view all the answers

<p>Higher stimulus intensity leads to a higher graded potential, which can repeatedly generate action potentials.</p> Signup and view all the answers

<p>Diffusion allows the rapid spread of ions across the cell membrane, facilitating the generation of action potentials.</p> Signup and view all the answers

<p>They are described as 'really fast' because the action potentials are generated at closely situated sites, allowing swift signal transmission.</p> Signup and view all the answers

<p>When the graded potential is insufficient, specifically below -55 mV, no action potentials are generated.</p> Signup and view all the answers

<p>The threshold at the axon hillock determines whether an action potential will be initiated, influencing overall neuronal communication.</p> Signup and view all the answers

<p>The cessation of stimulus implies a halt in the generation of action potentials, impacting neuronal signaling significantly.</p> Signup and view all the answers

<p>The rapid influx of Na+ is due to a large Na+ gradient and a significant electrical gradient.</p> Signup and view all the answers

<p>K+ channels open at +30 mV, leading to rapid efflux of K+ ions and a decrease in membrane potential.</p> Signup and view all the answers

<p>The three states are closed, open, and inactivated.</p> Signup and view all the answers

<p>During the refractory period, Na+ channels are inactivated, preventing the initiation of a new action potential.</p> Signup and view all the answers

<p>The Na+/K+ pump helps to reset the resting membrane potential by pumping Na+ out and K+ in.</p> Signup and view all the answers

<p>An action potential at site A raises the membrane potential of adjacent sites B and C to their thresholds.</p> Signup and view all the answers

<p>The inactivation of Na+ channels in the preceding segment prevents action potentials from traveling backward.</p> Signup and view all the answers

<p>If the stimulus remains sufficiently high, repeated action potentials can occur in response.</p> Signup and view all the answers

<p>The efflux of K+ ions results in a decrease in membrane potential towards -90 mV.</p> Signup and view all the answers

<p>Summation of graded potentials can trigger the voltage-regulated Na+ channels to open, initiating an action potential.</p> Signup and view all the answers