Presentation on theme: "Nerves and Stimuli. Stimulus – any perturbation in an animal’s internal or external environment which results in changes in membrane physiology of a receptor."— Presentation transcript:
CytosolExtracellular fluid Na + 15 mM K + 150 mM Cl - 120 mM A - 100 mM Na + 150 mM K + 5 mM Cl - 10 mM -60 to -70 mV negative
Action Potential Sodium (Na + ) ion Potassium (K + ) ion Sodium channel Potassium channel Activation gate Inactivation gate
Action Potential 3. Depolarization opens most Na + activation channels. Influx of Na + makes inside of cell +ve. 4. Inactivation channels close & block Na + influx. Activation gates on K + channels open & K + ions leave making cell more -ve. 5. Some K + channels are still open, allowing K + ions to escape and making the cell more -ve. As the K + gates close, the cell returns to its resting state. 1. Resting state - activation gates on K + and Na + channels are closed. 2. Stimulus opens activation gates on some Na + channels. Influx of Na + and depolarization.
Innate Releasing Mechanisms SIGN STIMULUS receptorCNS IRM Motor pattern Generated No motor pattern generated Match No match Motor output
Fixed Action Pattern (FAP) Egg Rolling in a Greylag Goose Egg-rolling video
A series of FAP’s can be put into a sequence Female Male 1. Appears -heads up display 2. Zig-zag swim 3. Swims head up to male 4. Swim to nest 5. follows 6. Show nest 7. Enters nest 8. Tremble thrust 9. spawn