Biology 1107 Exam 4 Study Guide (University Of Connecticut)

Biology 1107 Exam 4 Study Guide (University Of Connecticut) 8. Be able to describe the changes in membrane potential that occur during an action potential using the terms depolarize, hyperpolarize, and refractory period a. During AP, permeability changes rapidly from permeable to sodium, to not permeable to sodium, to very permeable to potassium b. Changes push the neuron to different EP c. More permeability to sodium drives the EP to sodium d. Depolarization - the difference in charge between inside and outside is decreasing, meaning the neuron is becoming more positive e. Hyperpolarization: difference in charge is increasing, the neuron is becoming more negative i. Both are driven by passive ion movement f. Action potential: an electrical impulse in a neuron, arises from the movement of ions (Na and K)- changes in channels g. Steps: i. Positive charge inside the cell ii. Cell reaches the threshold iii. There is a greater entry of positive charges iv. Drop in membrane potential past the resting potential h. Sodium potassium permeability underlies the changes i. Special changes in membrane potential occur during action potentials i. Voltage gated ion channels open and close due voltage changes (Electrochemical gradient) ii. Voltage changes dramatically over the course of time of action potential iii. Receives a signal to open ligand gated neuron channels causing opening of sodium channels and sodium to move down concentration gradient iv. Allow sodium to enter cell causing voltage increase v. Once neuron hits the threshold there is a dramatic change in what membrane is permeable 1. Massive depolarization due to rapid increase in sodium permeability since the voltage gated sodium channels are open vi. Eventually sodium ion channels close and potassium channels open and potassium moves out 1. This allows repolarization to occur and membrane potential lowers 2. When the potential gets low enough potassium channels close again vii. Regular processes begin slowly and neuron goes back to rest - refractory period - hyperpolarization is occurring 9. Identify how the electrical events of an action potential give rise to synaptic neurotransmission. a. Action potential has to arrive at the axon terminal b. Action potential propagated from where its generated at the cell body and goes all