أسئلة المحاضرة الـ 15 فسيولوجي (قبل التعديل)

<p>Electrical stimulation of the adjacent neuron.</p> Signup and view all the answers

<p>A second action potential can be generated with reduced magnitude.</p> Signup and view all the answers

<p>The membrane is close to the threshold but not quite back to resting state.</p> Signup and view all the answers

<p>It can reopen some of the Na+ channels that are closed.</p> Signup and view all the answers

<p>It leads to failure in initiation and propagation of nerve impulses.</p> Signup and view all the answers

<p>Myelinated nerve</p> Signup and view all the answers

<p>Saltatory conduction uses less energy</p> Signup and view all the answers

<p>Stimulation of the nerve</p> Signup and view all the answers

<p>The polarized resting node to depolarize</p> Signup and view all the answers

<p>-55 mV</p> Signup and view all the answers

<p>Increased velocity of conduction</p> Signup and view all the answers

<p>Uniform depolarization along the membrane</p> Signup and view all the answers

<p>-70 mV</p> Signup and view all the answers

<p>Increases conduction velocity</p> Signup and view all the answers

<p>Type A fibers</p> Signup and view all the answers

<p>Conduction in the normal direction</p> Signup and view all the answers

<p>Increase in myelin sheath thickness</p> Signup and view all the answers

<p>3-15 m/sec</p> Signup and view all the answers

<p>Type C fibers</p> Signup and view all the answers

<p>ATP</p> Signup and view all the answers

<p>0.5-1 μm</p> Signup and view all the answers

<p>Increase in CO2 production</p> Signup and view all the answers

<p>Excitability is completely lost</p> Signup and view all the answers

<p>When excitability is above normal</p> Signup and view all the answers

<p>It is caused by ATP reforming after the action potential</p> Signup and view all the answers

<p>Relative refractory period</p> Signup and view all the answers

<p>Generation and propagation of nerve impulses</p> Signup and view all the answers

<p>Relative refractory period</p> Signup and view all the answers

<p>Absolute refractory period</p> Signup and view all the answers

<p>120 m/sec</p> Signup and view all the answers

<p>Saltatory conduction uses approximately 1% of the energy of continuous conduction</p> Signup and view all the answers

<p>Node of Ranvier</p> Signup and view all the answers

<p>-55 mV</p> Signup and view all the answers

<p>Continuous conduction</p> Signup and view all the answers

<p>The node undergoes depolarization</p> Signup and view all the answers

<p>Local current flows between depolarized and resting areas</p> Signup and view all the answers

<p>Depolarization occurs without producing an action potential</p> Signup and view all the answers

<p>Gates of Na+ channels are just closing</p> Signup and view all the answers

<p>It prevents initiation and propagation of nerve impulses</p> Signup and view all the answers

<p>Most gates are in an open state but can be reopened by new stimuli</p> Signup and view all the answers

<p>The membrane is still partially repolarized</p> Signup and view all the answers

<p>No further action potential can be initiated</p> Signup and view all the answers

<p>Capacity to depolarize and generate action potentials</p> Signup and view all the answers

<p>Deep pressure or local anesthetics</p> Signup and view all the answers

<p>Thicker myelin increases membrane resistance to current</p> Signup and view all the answers

<p>Type A fibers</p> Signup and view all the answers

<p>1-3 μm</p> Signup and view all the answers

<p>Conduction occurring in the opposite direction of impulse</p> Signup and view all the answers

<p>Increased internal diameter</p> Signup and view all the answers

<p>Thin unmyelinated structure</p> Signup and view all the answers

<p>Conduction velocity decreases</p> Signup and view all the answers

<p>Purity of the nerve fiber</p> Signup and view all the answers

<p>Nerve fibers exhibit complete loss of excitability.</p> Signup and view all the answers

<p>Subnormal phase of excitability</p> Signup and view all the answers

<p>Relative refractory period</p> Signup and view all the answers

<p>They result in an increased production of CO2 and heat.</p> Signup and view all the answers

<p>It is associated with local depolarization before reaching the firing level.</p> Signup and view all the answers

<p>The generation and propagation of the nerve impulse.</p> Signup and view all the answers

<p>It results from metabolic reactions that reform ATP used during the action potential.</p> Signup and view all the answers

<p>Stimuli strength can vary from 0 to 100%.</p> Signup and view all the answers

<p>Saltatory conduction is significantly faster, reaching up to 120 m/sec, while continuous conduction typically ranges from 0.5 to 2 m/sec.</p> Signup and view all the answers

<p>Saltatory conduction requires only 1% of the energy that continuous conduction consumes due to fewer depolarization events.</p> Signup and view all the answers

<p>The initial heat production is due to the generation and propagation of the nerve impulse.</p> Signup and view all the answers

<p>The node of Ranvier serves as the site where action potentials are generated and allows ions to flow in and out, facilitating rapid conduction.</p> Signup and view all the answers

<p>During the absolute refractory period, excitability is completely lost, while in the relative refractory period, excitability is partially recovered.</p> Signup and view all the answers

<p>At the site of stimulation, the membrane becomes depolarized to +35 mV, triggering a local current that depolarizes adjacent resting areas.</p> Signup and view all the answers

<p>In the supernormal phase, the excitability of the nerve fibers is above normal.</p> Signup and view all the answers

<p>The threshold for action potential initiation is typically -55 mV, which must be reached during the depolarization process.</p> Signup and view all the answers

<p>There is an increase in CO2 production, glucose utilization, and heat production.</p> Signup and view all the answers

<p>A potential difference is established between the active node (depolarized to +35 mV) and the adjacent resting node (-70 mV), generating local currents.</p> Signup and view all the answers

<p>ATP reform is necessary to replenish energy used during the action potential.</p> Signup and view all the answers

<p>Myelination increases conduction velocity by allowing faster transmission of action potentials through saltatory conduction.</p> Signup and view all the answers

<p>In the subnormal phase, weak stimuli can still excite the nerve but require stronger stimuli than normal.</p> Signup and view all the answers

<p>Saltatory conduction enhances conduction velocity and conserves energy, which is crucial for efficient nerve function.</p> Signup and view all the answers

<p>Local depolarization triggers the initial increase in excitability leading to action potential firing.</p> Signup and view all the answers

<p>A strong stimulus is required to evoke an action potential during the relative refractory period.</p> Signup and view all the answers

<p>Strong stimuli can reopen some of the previously activated Na+ channels, but not all of them during the ascending limb.</p> Signup and view all the answers

<p>The nerve membrane is partially repolarized, and not all Na+ gates are open, leading to a reduced magnitude of the action potential.</p> Signup and view all the answers

<p>The negative afterpotential occurs as the membrane hyperpolarizes, making it less likely to fire another action potential immediately.</p> Signup and view all the answers

<p>During the absolute refractory period, the nerve fiber cannot be excited to generate a second action potential, regardless of the strength of a stimulus.</p> Signup and view all the answers

<p>Local anesthetics such as lidocaine inhibit the initiation and propagation of nerve impulses, reducing excitability.</p> Signup and view all the answers

<p>Hyperpolarization increases the threshold for depolarization, requiring a stronger stimulus to generate another action potential.</p> Signup and view all the answers

<p>Severe cooling leads to a failure in the initiation and propagation of nerve impulses, resulting in decreased nerve excitability.</p> Signup and view all the answers

<p>Sufficient repolarization is necessary to reopen Na+ channels, allowing a second action potential to be generated.</p> Signup and view all the answers

<p>A larger diameter decreases internal resistance, which increases conduction velocity.</p> Signup and view all the answers

<p>Myelination increases membrane resistance, allowing charge to jump between nodes and speeding up conduction.</p> Signup and view all the answers

<p>Orthodromic conduction travels in the normal direction, while antidromic conduction occurs in the opposite direction.</p> Signup and view all the answers

<p>Type A fibers conduct at 10-120 m/sec, Type B at 3-15 m/sec, and Type C at 0.5-2 m/sec.</p> Signup and view all the answers

<p>Type C fibers are most sensitive to local anesthetics due to their thin, unmyelinated structure.</p> Signup and view all the answers

<p>The RMP allows nerve fibers to respond to stimuli and maintain excitability for action potentials.</p> Signup and view all the answers

<p>Saltatory conduction consumes less energy than continuous conduction due to fewer action potentials being generated.</p> Signup and view all the answers

<p>Type A fibers are sensitive to prolonged deep pressure and oxygen lack (hypoxia).</p> Signup and view all the answers

<p>A larger internal diameter decreases internal resistance, which increases conduction velocity.</p> Signup and view all the answers

<p>The myelin sheath increases membrane resistance, allowing the charge to jump between nodes, which speeds up conduction.</p> Signup and view all the answers

<p>Orthodromic conduction occurs in the normal direction, while antidromic conduction occurs in the opposite direction.</p> Signup and view all the answers

<p>Type A fibers conduct action potentials at speeds ranging from 10 to 120 m/sec.</p> Signup and view all the answers

<p>Type C fibers are most sensitive to prolonged deep pressure and oxygen lack (hypoxia).</p> Signup and view all the answers

<p>Continuous conduction is slow, ranging from 0.5 to 2 m/sec, while saltatory conduction can reach speeds of up to 120 m/sec.</p> Signup and view all the answers

<p>Nerve fibers use ATP generated from metabolic processes as the energy source to maintain RMP.</p> Signup and view all the answers

<p>The node of Ranvier facilitates the rapid depolarization of the nerve membrane, allowing the action potential to jump from one node to the next.</p> Signup and view all the answers

<p>Increased myelin sheath thickness enhances conduction velocity by increasing membrane resistance to current.</p> Signup and view all the answers

<p>Continuous conduction consumes more energy, whereas saltatory conduction uses only about 1% of the energy required for continuous conduction.</p> Signup and view all the answers

<p>Type B nerve fibers generally have a diameter range of 1 to 3 μm.</p> Signup and view all the answers

<p>Depolarization occurs when a stimulation causes a local current to flow, transforming the resting potential from -70 mV to the threshold level of -55 mV.</p> Signup and view all the answers

<p>The primary significance is an increased velocity of conduction and conservation of energy during impulse transmission.</p> Signup and view all the answers

<p>The resting membrane potential at a polarized resting node is typically around -70 mV.</p> Signup and view all the answers

<p>Continuous conduction requires a higher metabolic energy output compared to saltatory conduction, which is more energy-efficient.</p> Signup and view all the answers

<p>After reaching +35 mV, the neuronal membrane repolarizes, transitioning back toward the resting membrane potential.</p> Signup and view all the answers

<p>The membrane is partially repolarized and not all Na+ channels are opened.</p> Signup and view all the answers

<p>It can lead to depolarization and the production of a second action potential if the membrane is sufficiently repolarized.</p> Signup and view all the answers

<p>Excitability relates to the opening and closing of voltage-gated Na+ channels following depolarization and repolarization phases.</p> Signup and view all the answers

<p>The membrane potential moves away from the threshold, making it less likely for a new action potential to occur.</p> Signup and view all the answers

<p>Mechanical stimuli can alter the excitability of nerve fibers by affecting the permeability of the membrane to ions.</p> Signup and view all the answers

<p>Severe cooling can impede nerve excitability and conductivity, potentially leading to failure in impulse propagation.</p> Signup and view all the answers

<p>During this period, the nerve fiber cannot be activated to generate another action potential, regardless of the stimulus strength.</p> Signup and view all the answers

<p>Repolarization resets the membrane potential, establishing conditions for future action potentials but temporarily limits the number of impulses that can be conducted.</p> Signup and view all the answers

<p>The two phases are initial heat, which occurs during the generation and propagation of the nerve impulse, and delayed heat, which results from metabolic reactions to reform ATP.</p> Signup and view all the answers

<p>During the ARP, the excitability of the nerve fiber is completely lost, meaning no stimuli can excite the nerve regardless of strength.</p> Signup and view all the answers

<p>During the RRP, the nerve fiber's excitability is partially recovered, requiring stronger stimuli than usual to evoke an action potential.</p> Signup and view all the answers

<p>In the supernormal phase, the excitability of the nerve fiber is above normal, allowing weaker stimuli to excite the nerve.</p> Signup and view all the answers

<p>Increased metabolic activity leads to heightened CO2 production as a byproduct of enhanced metabolic reactions during nerve impulse conduction.</p> Signup and view all the answers

<p>There is an increase in glucose utilization when nerve impulses are conducted, reflecting the heightened energy demands of the active nerve fibers.</p> Signup and view all the answers

<p>The local response is associated with local depolarization in the nerve fiber, which leads to a temporary increase in excitability before reaching the firing level.</p> Signup and view all the answers

<p>The delayed heat phase is attributed to the metabolic reactions needed to reform ATP that was consumed during the action potential.</p> Signup and view all the answers