Potassium ions: a. Phase 0: rapid upstroke of the AP (Sodium Current). What happens to overall membrane potential as the potassium ions diffuse out? Why does this happen? Laboratory Report LABORATORY REPORT Activity: Action Potentials Name: Iker Nguyen Instructor: Chang, Steven Date: 02.16.2021 Predictions 1. phases and primary currents in the ventricle muscle action potential : A. Depolarization of the first membrane patch causes permeability changes in the adjacent membrane, and the events described in step are repeated. increases 2. Opening of voltage-regulated fast sodium channels triggered by entry of positive ions from adjacent cell: Depolarization due to rapid influx of sodium 2. What happens to potassium ions when the potassium “doors” open? 21. membrane potential is what we call the action potential (AP), an electric potential that causes an action (here a muscle twitch). What kind of transport is this? In Bernstein’s theory, depolarization at one point of the How does the AP travel along the nerve? 7. a. Conduction velocity along the axon is increased by what two characteristics? • Initiation of action potential in contractile cells: 1. b. Action Potential The action potentials obey the “all or none” law—once a stimulus is strong enough to exceed the threshold of excitation a fully fledged action potential ensues. more less) depolarized. 3. another action potential but only if the membrane is __ _____ period, the cell can generate . nals such as the action potential. The Action Potential, a BrainU video 18. Important: I have decided to refrain from fully explaining action potentials in this course. 19. Action potentials convey information within the brain. 20. What does the movement of positive potassium ions cause in the cell? Phase 1: small repolarization (Transient Outward Current) C. Phase 2: plateau (Calcium Current) D. Phase 3: final repolarization ( Delayed Rectifier Current) E. Phase 4: the resting potential (Inward Rectifier Current) _ the diameter of the axon 2. 4 2 You can learn the details in the following ways: _____ (more or . Helmholtz had found that the AP travelled along the frog’s nerve at about 27 m=s. 1. Plateau produced by calcium influx balancing potassium … Exceeding threshold depolarization at the trigger zone_____the likelihood of generation of an action potential. B. An action potential has two main phases: a depolarizing phase and a repolarizing phase. Action potential amplitude does not change with distance 3. An action potential is a burst of electrical activity, it lasts about a millisecond (0.001 second). In Chapter 8 we shall consider how the passive properties of neurons-their resistive and capacitive characteristics-contribute to local signaling within the neuron. PROPAGATION OF THE ACTION POTENTIAL -Lets say, an action potential arrives to the patch of axon we are looking at-The membrane is constantly at about -70 millivolts, but when it gets to -60 the voltage-gated sodium channels open and let a stream of sodium into the cell-This causes the membrane to DEPOLARISE, that is, to approach 0 millivolts. C H A P T E R The Action Potential, 3 Synaptic Transmission, and Maintenance of Nerve Function Cynthia J. Forehand, Ph.D. CHAPTER OUTLINE PASSIVE MEMBRANE PROPERTIES, THE ACTION NEUROCHEMICAL TRANSMISSION POTENTIAL, AND ELECTRICAL SIGNALING BY THE MAINTENANCE OF NERVE CELL FUNCTION NEURONS SYNAPTIC TRANSMISSION KEY CONCEPTS 1. Propagation of the action potential. Thus, the action potential propagates rapidly along the entire length of the membrane.