10 12 14 Electrical Signals From Res3ng Poten3al to Ac3on Poten3al Lesson 22 BIOL 1108 13 October 2014 1 Unit Animal Form and Func on Today s Topic D Res ng Poten al to Ac on Poten al D Today s learning objec ves Be able to describe what an ac on poten al is including depolariza on hyperpolariza on 2 1 10 12 14 What two factors in uence membrane poten al 1 Ion concentration diffusion 2 Electrical force What is the res ng membrane poten al of an axon 70 mV 3 0 Graded Potential 0 Time What happens to the membrane poten al with increased permeability to K Membrane poten al mV Membrane poten al mV Hyperpolariza on vs Depolariza on in the Axon 0 0 Time What happens to the membrane poten al with increased permeability to Na 4 2 10 12 14 How is an ac on poten al generated in an axon Let s nd out Shake hands with your neighbor 5 Genera ng an Ac on Poten al 62 3 All Na voltage gated channels open D55 2 1 resting potential Na channels start to close K channels begin to open 4 1 5 6 3 10 12 14 Genera ng an Ac on Poten al Voltage Gated Channel State Charge Phase Na K Membrane Poten3al mV 1 Closed Closed 2 Some Open Closed 70 55 3 All Open Closed 55 45 4 Most Closed Open 45 70 5 Closed Some Open 70 90 1 Closed Closed Inside the Cell 70 mV 70 Outside the Cell 7 Figure 48 11 5 Key Na K 4 Falling phase of the action potential 50 Membrane potential mV 3 Rising phase of the action potential OUTSIDE OF CELL Sodium channel 3 0 50 2 Depolarization Action potential Threshold 2 1 4 5 1 Resting potential 100 Time Potassium channel INSIDE OF CELL Inactivation loop 1 Resting state 5 Undershoot 8 4 10 12 14 Genera ng an Ac on Poten al 62 At which phase does depolariza on rst occur C D D55 B A F E 9 Genera on of an Ac on Poten al 62 D55 An ac on poten al is triggered when the membrane poten al reaches A D90 mV B D70 mV C D55 mV D 55 mV 10 5 10 12 14 Genera on of an Ac on Poten al D Does the strength of a s mulus a ect the ac on poten al size or frequency 11 Genera ng an Ac on Poten al 62 At which phase is the refractory period C D D55 B A F E 12 6 10 12 14 Animal Form and Func on Electrical Signals D Res ng Poten al to Ac on Poten al D Today s learning objec ves Be able to describe what an ac on poten al is including depolariza on hyperpolariza on Think about D When you shook your neighbor s hand how did the signal reach your brain 13 7