Subject: Neurophysiology Batrachotoxin OPENS Na+ channels. If this is added to a bath solution in a Neuromuscular junction preparation a. What would happen to the nerve resting membrane potential? b. Do you think that the toxin interacts with activation or inactivation gates? Why? c. Na ion influx is massive with Batrachotoxin. Would you predict a change in nerve cell volume? Why?

Subject: Neurophysiology Batrachotoxin OPENS Na+ channels. If this is added to a bath solution in a Neuromuscular junction preparation a. What would happen to the nerve resting membrane potential? b. Do you think that the toxin interacts with activation or inactivation gates? Why? c. Na ion influx is massive with Batrachotoxin. Would you predict a change in nerve cell volume? Why?

Human Physiology: From Cells to Systems (MindTap Course List)

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter4: Principles Of Neural And Hormonal Communication

Section: Chapter Questions

Problem 1SQE: Answer the following questions regarding conduction of action potentials using the velocities given...

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Subject: Neurophysiology During an action potential the Na+ current is inward and K+ current is outward. You may have been surprised to learn that the intracellular concentration of those ions does not change even after many action potentials. Why not?
A. Is an action potential more or less likely when the consumption of the Fugu toxin and is stimulated with a neuron with a supra-threshold stimulus? B. Which (flaccid or tonic) is the result in this case? What would be the associated physical symptoms of this condition? C. Briefly describe the pharmacological/clinical/commercial uses of this toxin and its derivatives.
Match the stages of action potential with the appropriate image or description. PICK AND MATCH FROM THESE 1. Resting membrane potential 2. Threshold 3. Depolarization 4. Repolarization 5. Hyperpolarization 6. Refractory period The potential difference that must be met in order for an action potential to be generated When the potential drops below resting level Location 3 on this image When the potential starts to decrease again after it has reached a maximum Location 4 on this image Occurs at -77 mV When the membrane is resetting and an action potential cannot yet be produced again When the sodium channels are open Occurs at -55 mV
Place the steps of the action potential in order. 3. a brief reversal of membrane potential that travels along the axon mechanism that restores the resting membrane voltage and intracellular ionic concentrations 2.C reversal of the resting potential due to an influx of sodium ions 1. period during which potassium ions are diffusing out of the neuron because of a change in membrane permeability
Determine whether each statement is true or false. If a statement is false, explain why. A. Voltage gated sodium channels are quick to open and slow to close, while voltage gated potassium channels are quick to open and slow to close. 6. Before a second action potential can be generated, the concentration of sodium and potassium on either side of the cell membrane must be fully restored. C. The strength of an action potential is represented by the amplitude of the wave. A stronger stimulus will generate an action potential with a higher peak than a weaker stimulus. D.. Action potentials travel in a non-decremental manner down the axon, with the voltage constantly being regenerated along the way, unlike graded potentials which quickly diminish over short distances. E. Contiguous conduction is faster than saltatory conduction. F. Action potentials originate in the axon hillock and travel down the axon to the terminal boutons (pre-synaptic axon terminals).
Subject: Neurophysiology Imagine a toxin that blocks voltage gated K channels. What do you expect to see at the neuromuscular junction when you stimulate the pre synaptic neuron? Would you release neurotransmitter? Would the skeletal muscle contract?
Describe the events that occur during action potential ANSWER SHOULD INCLUDE: Explanation of how resting membrane potential works and which ions inside/outside Expiation of how depolarisation membrane occurs and which ions move in/how they move in . Explanation of "threshold" . Explanation of depolarisation and which ions move out and how they move out. Explanation of hyperpoarisation and how it is corrected. ( state membrane potential in mv during each stage )
PARTICIPATION ACTIVITY: For each toxic effect below, use your knowledge of the phases of an action potential to determine which image most likely corresponds with that effects of that toxin. A “quiz-like" link will be posted on Canvas after lecture today for you to upload your responses. Due by 11:59 pm tonight via Canvas. No visible effect or the action potentia of a typical neuron A C Effect of the Toxin Toxin C A B Letter 30 30 10 10 Delayed closing of the voltage-gated sodium channels after opening -10 -10 -30 -30 -50 Toxin A -50 Prevents voltage-gated sodium Toxin B -70 -70 -90 channels from opening when stimulated -90 4 6. 8 10 10 Time (ms) Time (ms) Causes voltage-gated potassium channels to open even without a 30 30 voltage stimulus Prevents the voltage-gated calcium 10 10 -10 -10 -30 -30 Toxin C -50 Toxin D -50 channels from opening when stimulated -70 -70 -90 4 6. 10 4 6 8 10 Time (ms) Time (ms) Prevents the voltage-gated potassium channels from opening when stimulated Hint:…
In temporal summation.. Select one: O A. IPSPS, but not EPSPS, are combined. O B. The postsynaptic cell's potential is a combination of two EPSPS arriving at a synapse in rapid succession. O C. Two synapses on different regions of a cell are stimulated at the same time. O D. A synapse is stimulated a second time after the effect of a first stimulus at the synapse has been terminated. O E. The size of an action potential depends on the size of the stimulus.
E. ACTION POTENTIAL Describe what happens in each phases of action potential and explain the following events in the illustration below. 3. Peak action potential +30 Repolarization Threshold of excitation -55 2 1 Hyperpolarization -70 Resting potential 4 Time [Enter description here] Membrane potential (mV)
A. Why small children (generally before and around the stage of toddlers) tend to fall, while later on they will develop improved mobility. Briefly explain this limited mobility in their early years in terms of the formation and maturation of the different components of the nervous system structures. B. How does a typical skeletal muscle and a typical neuron behave differently when they get depolarized? If you block the achetalcholine receptors on the plasma membrane of these two types of cells, what would be the effect on the response of each of these two cell types? why.
Match the stages of action potential with the appropriate image or description. 1. Resting membrane potential 2. Threshold 3. Depolarization 4. Repolarization 5. Hyperpolarization 6. Refractory period The potential difference that must be met in order for an action potential to be generated When the potential drops below resting level When the potential starts to decrease again after it has reached a maximum Occurs at -77 mV When the membrane is resetting and an action potential cannot yet be produced again When the sodium channels are open Occurs at -55 mV