Neurophysiology Study Guide 1. Define "equilibrium potential". Why is the resting potential closer to the potassium equilibrium potential (EK+) than the sodium potential (ENa+)? The equilibrium potential is the point at which the force exerted on an ion by electrostatic and concentration gradient forces are balanced‚ and there is no net movement of that ion. The resting potential is closer to EK+ than ENa+ because the cell membrane is more permeable to
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only a change in the conformation of retinal‚ which happens very quickly. In order to adapt to dark conditions‚ a lot of rhodopsin (retinal+opsin) needs to build up and that takes time. 4. If the duration of the absolute refractory period of a nerve cell is 1.5msec‚ how many a.p. are generated in 1sec by a maximal stimulus? If you can fire an action potential every 1.5msec‚ then you should be able to generate (1000msec 1.5 msec) or about 667 a.p.s per second. 5. Bethanechol chloride is a
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Physiology Exercise 3 Activity 1 1. Explain why increasing extracellular K+ reduces the net diffusion of K+ out of the neuron through the K+ leak channels. Your answer: By increasing the extrecellular K+ the net diffiusion of K+ out the neuron through the eak channels is reduced. This is caused by the flow of ions following the concentration gradient of traveling from an area of high concentration to areas of low concentration. The higher concentration gradient would result in a reduced diffusions
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Anatomy of Peripheral Nerves Peripheral nerves consist of fascicles that contain myelinated and unmyelinated axons. Endoneurium is the small amount of matrix that is present between individual axons. The perineurium is a sheath of special‚ fiber-like cells that ties the axons of each fascicle together. Epineurium is the connective tissue that surrounds the entire nerve trunk and gives off vascular connective tissue septa that traverse the nerve and separate fascicles from one another. | | Single
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current is directed over the nerves that lead to those electrodes so that a computer can record and evaluate the consequent nerve impulse for velocity‚ onset and amplitude. Neuropathies are caused by damage to the nerves axon and/or damage to the myelin sheath surrounding the nerve. If a response is slower than normal‚ damage to the myelin sheath is implied. If the height of the response’s amplitude is low with a relatively normal speed of conduction‚ damage to the nerve axon is implied. How
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10/22/2012 Communication Along and Between Neurons (Ch.6) • Receptors receive stimuli‚ and convert them to nerve impulses • Alternating graded and all-or-none signals on the membrane of a single neuron • Graded potentials decay with distance (electrotonic conduction); longdistance transmission depend on transforming signals to APs • Typically‚ alternating electric (within neuron) and chemical signals (between neurons) • Postsynaptic potential affected by number and frequency of APs
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Alcoholic neuropathy defines the nerve disorder associated with excessive alcohol consumption. Nerve function is reduced‚ it is believed‚ by the toxins in alcohol and nutritional deficiencies. Normal symptoms for alcoholic neuropathy include lack of sensation‚ tingling‚ frail ankles and muscles and burning feet. Diarrhea‚ nausea/vomiting‚ constipation‚ incontinence of the bladder and impotence in men are some other symptoms. However‚ in severe cases of alcoholic neuropathy‚ major damage is done
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Electromyography In this experiment‚ you will explore the electrical activity of skeletal muscle by recording an electromyogram (EMG) from a volunteer. You will examine the EMG of both voluntary and evoked muscle action and attempt to measure nerve conduction velocity. Written by staff of ADInstruments. [pic] Background A skeletal muscle fiber is innervated by a branch of a motor axon. Under normal circumstances‚ a neuronal action potential activates all of the muscles innervated by the motor
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3: Neurophysiology of Nerve Impulses: Activity 7: The Action Potential: Conduction Velocity Lab Report Pre-lab Quiz Results You scored 100% by answering 5 out of 5 questions correctly. 1. An action potential can be propagated along an axon because there are __________ channels in the membrane. You correctly answered: d. voltage-gated 2. The units of conduction velocity are You correctly answered: d. meters/second. 3. Which of the following will affect axonal conduction velocity? You correctly answered:
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Sample Physiology MCQs 1. Compound action potentials can be graded responses. True 2. The sciatic nerve contains axons of both afferent and efferent neurones. True 3. The absolute refractory period of an action potential is the period after an initial stimulus when it is impossible to evoke another action potential with a second stimulus. True 4. The refractory periods of individual axons are important as they dictate the maximal action potential firing rate of a neuron. True 5. Compound action
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