this experiment was to examine how the compound action potentials propagate down the sciatic nerve of a frog based on varying stimuli. Before the nerve could be tested it needed to be extracted from the thigh of the frog and then submerged in saline. Several varying stimuli were used and recorded by a software package. The second experiment requires a constant stimulus with varying reference pin locations. From this the velocity of the action potential propagated can be determined. The experiment revealed
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fundamental unit of the nervous system. These neurons work together with other excitable cells to produce action potentials when they receive electrical or chemical stimuli. Action potentials can be thought of as an “all-or-nothing” event and occur as a large-scale depolarization when sodium and other positive ions rapidly enter the neuron through membrane channel proteins. Once initiated‚ action potentials travel down the length of the axon and when it reaches the end a neurotransmitter is released into
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Resting membrane potentials Definition: Large nerve fibers when not transmitting nerve signals is about 90 millivolt. That is‚ the potential inside the fiber is 90 millivolts more negative than the potential in the extracellular fluid on the outside of the fiber. The Na+-k+ pump also causes large concentration gradients for sodium and potassium across the resting nerve membrane. These gradients are the following: Sodium ( outside): 142 mEq/L Sodium ( inside): 14 mEq/L Potassium ( outside):
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(a) Define the term equilibrium potential and use the Nernst equation (see Appendix) to show how the equilibrium potentials for both sodium and potassium are calculated. Equilibrium potential is the potential of the membrane when there is no net flow of ions from one gradient to the other gradient. The ions are equal and are opposite of each other but not moving from one side to the other. Sodium: Ena=2.303((8.31 J m-1 K-1)(310K))/((1(= 9.65 x 104 c m-1))(log(150/15))= 61.54 mV Ek=2.303((8
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Abstract This article is investing the effects of speed of the action potential across many neurons through investigating two diseases and performing related lab simulations. Multiple sclerosis and epilepsy are the two disease which are investigated and through the use of Neurons in Action lab simulations‚ we saw the effects that demyelination and channelopathy can have. As my hypothesis guessed‚ demyelination is the main cause of multiple sclerosis and channelopathy is the main cause of epilepsy
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which cell has the larger resting membrane potential? Explain. If the permeability to K is higher in A than in B‚ then the resting membrane potential (rmp) will be closer to the equilibrium potential in cell A‚ which means the rmp will be more negative in cell A than in cell B; or in other words‚ the potential difference will be LARGER in cell A. 2. Predict the effect of a reduced extracellular concentration of Na+ on the magnitude of the action potential in an electrically excitable cell. If there
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Objective: To define a method to “Determine the effect and site of action of strychnine”. Requirements: Apparatus: * Beakers. * Syringe. * Mask. * Gloves. Subject: * Healthy Frog. Scope: Strychnine is highly toxic‚colorless‚crystalline alkaloid cause killing of small vertebrates e.g‚ dogs‚rodents because its site of action is spinal cord. Symptoms of severity: Severe nausea and vomiting ‚convulsions of
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The formation of an action potential can be divided into five steps. (1) A stimulus from a sensory cell or another neuron causes the target cell to depolarize toward the threshold potential. (2) If the threshold of excitation is reached‚ all Na+ channels open and the membrane depolarizes. (3) At the peak action potential‚ K+ channels open and K+ begins to leave the cell. At the same time‚ Na+ channels close. (4) The membrane becomes hyperpolarized as K+ ions continue to leave the cell. The
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The Nervous System: Membrane Potential 1. Record the intracellular and extracellular concentrations of the following ions (mM/L): Intracellular Extracellular Sodium (Na+) Potassium (K+) Chloride (Cl–) 2. Excitable cells‚ like neurons‚ are more permeable to ___________ than to ___________. 3. How would the following alterations affect the membrane permeability to K+? Use arrows to indicate the change in permeability. a. An increase in the number of passive K+ channels
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THE WORK DONE BY A CONSERVATIVE FORCE ALWAYS HAS FOUR PROPERTIES: 1. It can be expressed as the difference between the initial and final values of a potential-energy function. 3. It is independent of the path of the body and depends only on the starting and ending points. 2. It is reversible. 4. When the starting and ending points are the same‚ the total work is zero. The total mechanical energy ME = K + U is constant. Object moving in a uniform gravitational field gravitational a
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