Which ion most readily leaks across a neuron's membrane, helping to establish the resting potential?

Which of these statements about myelination in neurons is/are correct? Select True or False for each statement. T/F It speeds propagation by increasing the density of voltage-gated channels all along the axon. T/F Multiple sclerosis is characterized by disrupted myelination of certain neurons in the central nervous system. T/F It speeds propagation by preventing cations from leaking out across the membrane as they spread down the axon. T/F It is more commonly observed in vertebrates than in invertebrates.

In a neuron, what creates the electrochemical gradient favoring the outflow of K+ when the cell is at rest? a. Na+/K+-ATPase b. voltage-gated K+ channels c. voltage-gated Na+ channels d. ligand-gated Na+/K+ channels

Which of the following brain regions is responsible for formation of new memories? a. brainstem b. cerebellum c. frontal lobe d. hippocampus

Explain the difference between a ligand-gated K+ channel and a voltage-gated K+ channel.

Describe the role of summation in postsynaptic cells.

Compare and contrast the somatic nervous system and autonomic nervous system.

Why is memory thought to involve changes in particular synapses? a. At some synapses, more neurotransmitters are released after learning takes place. b. At some synapses, a different type of neurotransmitter is released after learning takes place. c. When researchers stimulated certain neurons electrically, individuals replayed memories. d. When researchers changed synapses in the brains of patients during surgery, the patients' memories changed.

Explain why drugs that prevent neurotransmitters from being taken back up by a presynaptic neuron have dramatic effects on the activity of postsynaptic neurons.

Alzheimer's disease is a common form of dementia affecting millions of people, especially the elderly. Two regions of the brain are particularly affected, often shrinking dramatically and accumulating large deposits of extracellular material. Based on your knowledge of memory, what two brain regions do you think these are? Explain.

Certain species of frogs in the genus Phyllobates have a powerful defensive adaptation—their skin can secrete a milky fluid that contains an extremely toxic compound called batrachotoxin (BTX). These frogs, which are found in Colombia, are known as poison dart frogs because some indigenous Colombian hunters coat the tips of their blowgun darts with the frogs' skin secretions. An animal hit by one of these darts dies quickly. What is the mechanism of action of BTX? The graph here shows the effect of BTX on the membrane potential of a squid giant axon. Which of the following is the most likely explanation for the effect of BTX on the squid giant axon? a. inactivation of Na+/K+-ATPase b. closing of sodium channels c. opening of sodium channels d. opening of potassium channels

Certain species of frogs in the genus Phyllobates have a powerful defensive adaptation—their skin can secrete a milky fluid that contains an extremely toxic compound called batrachotoxin (BTX). These frogs, which are found in Colombia, are known as poison dart frogs because some indigenous Colombian hunters coat the tips of their blowgun darts with the frogs' skin secretions. An animal hit by one of these darts dies quickly. What is the mechanism of action of BTX? Identify a research technique that could be used to discover how BTX affects specific membrane proteins. Based on the graph in Question 11, what would you expect this technique to show?

Certain species of frogs in the genus Phyllobates have a powerful defensive adaptation—their skin can secrete a milky fluid that contains an extremely toxic compound called batrachotoxin (BTX). These frogs, which are found in Colombia, are known as poison dart frogs because some indigenous Colombian hunters coat the tips of their blowgun darts with the frogs' skin secretions. An animal hit by one of these darts dies quickly. What is the mechanism of action of BTX? As the graph in Question 11 shows, BTX depolarizes the membrane and prevents repolarization. What effect would this have on electrical signaling by the nervous system?

Certain species of frogs in the genus Phyllobates have a powerful defensive adaptation—their skin can secrete a milky fluid that contains an extremely toxic compound called batrachotoxin (BTX). These frogs, which are found in Colombia, are known as poison dart frogs because some indigenous Colombian hunters coat the tips of their blowgun darts with the frogs' skin secretions. An animal hit by one of these darts dies quickly. What is the mechanism of action of BTX? Like neurons, cells in skeletal and cardiac muscle also produce action potentials. Create a concept map showing how BTX could kill a mammal through its effects on nervous and muscle tissues.

Certain species of frogs in the genus Phyllobates have a powerful defensive adaptation—their skin can secrete a milky fluid that contains an extremely toxic compound called batrachotoxin (BTX). These frogs, which are found in Colombia, are known as poison dart frogs because some indigenous Colombian hunters coat the tips of their blowgun darts with the frogs' skin secretions. An animal hit by one of these darts dies quickly. What is the mechanism of action of BTX? Predict the effects of each of the following on the membrane potential of a neuron simultaneously poisoned with BTX: (a) removing extracellular sodium ions; (b) increasing the intracellular potassium ion concentration; and (c) adding tetrodotoxin from puffer fish.

Certain species of frogs in the genus Phyllobates have a powerful defensive adaptation—their skin can secrete a milky fluid that contains an extremely toxic compound called batrachotoxin (BTX). These frogs, which are found in Colombia, are known as poison dart frogs because some indigenous Colombian hunters coat the tips of their blowgun darts with the frogs' skin secretions. An animal hit by one of these darts dies quickly. What is the mechanism of action of BTX?Although BTX is a powerful antipredator poison, one snake species in Colombia eats poison dart frogs. Suggest a hypothesis that might explain how the snake is resistant to the toxin.