Chapter 2. PART B. Communication within- and between-neurons (membrane potentials) Highlighted sections Communication within a neuron Communication between neurons Activation of receptors, postsynaptic potentials, termination of postsynaptic potentials; Neural integration 1. Is the inside of the membrane positively or negatively charged with respect to the outside? 2. Define resting potential in your own words, making sure to use the words (a) dynamic equilibrium, (b) electrostatic force, (c) diffusion force, (d) selective membrane, (e) sodium, (f) potassium, (g) ATP sodium/potassium pump, (h) ion channels. 3. If a positive electrical stimulus is applied to the inside of the membrane, what will be the effect on the membrane potential? What term is used to describe this change? 4. What happens to the membrane potential when the membrane receives a very weak depolarizing stimulus? 5. Describe what happens to the electrical charge across the membrane after it receives a sufficiently large stimulus 6. Copy from memory the graph of an action potential sure to label x-axis, y-axis, threshold, action potential, hyperpolarization, and depolarization. 7. About how long does the entire process –from the electrical stimulus to the return to normal resting potential- take? ___________ 8. A spoonful of sugar has been poured into a container of water. What eventually happens to the sugar? What process does this describe? ____________ 9. ______________ are substances that split into two parts when dissolved in water. The charged particles into which they decompose are called _______________. ______________ have a positive charge and _____________ have a negative charge. The force of attraction or repulsion between these particles is called _______________. 10 . describe the step-by-step conduction of the action potential along the myelinated axon using these terms in this order. a. Schawnn cells b. Nodes of Ranvier c. inward flow of sodium d. extracellular sodium e. cable properties f. decremental conduction g. renewed signal strength h. saltatory conduction 24. Identify an advantage of saltatory conduction. Communication between neurons 1. Define postsynaptic potential in your own words, noting its two possible effects on an axon. 2. A synapse is a(n) ________________ between the _______________ ________________ at the ends of axons of one neuron with the ______________ of another neuron. The membrane of the transmitting neuron is called the ___________________ membrane, and the message is received by the ___________________ membrane. 3. When molecules of the neurotransmitter diffuse across the synaptic cleft to the postsynaptic membrane, what structures do they bind with? Once binding occurs, what happens next? 4. a) Describe the movements of sodium and potassium ions during an EPSP and an IPSP. b) Now describe the movement of chloride. Key terms Membrane potential Oscilloscope Resting potential Depolarization Hyperpolarization Action potential Threshold of excitation Diffusion Ion Sodium-potassium transporter Voltage-dependent ion channel Cable properties Salutatory conduction Postsynaptic potential Neuromodulator Endocrine gland Target cell Binding site Ligand Presynaptic membrane Postsynaptic membrane Synaptc cleft Postsynaptic receptor Neurotransmitter-dependant ion channel Second messenger Excitatory postsynaptic potential (EPSP) Inhibitory postsynaptic potential (IPSP) Reuptake Enzymatic deactivation Acetylcholinesterase (AChE) Neural integration Neuronal firing