Neurons and Action Potentials

What is the function of the giant axon in a squid?

• To move the squid's tail

• To innervate the squid's mantle muscle

• To send electrical signals to the brain

• To regulate the squid's body temperature

What causes an electrical signal in neurons?

• Chemicals

• Light

• Sound

• Heat

Which ions are important in the nervous system?

• Sodium and potassium

• Calcium and chloride

• Sodium and calcium

• Potassium and chloride

What is the resting membrane potential of a neuron?

• -70 mV

• -55 mV

• 0 mV

• +70 mV

What is an action potential?

• An explosion of electrical activity in a neuron

• The resting state of a neuron

• The movement of ions across the neuron membrane

• The threshold level of a neuron

What happens when a neuron reaches the threshold level?

• An action potential is fired

• The neuron becomes hyperpolarized

• The neuron returns to resting potential

• The neuron stops sending signals

What causes depolarization in a neuron?

• Sodium ions rushing into the neuron

• Potassium ions rushing out of the neuron

• Chloride ions crossing the neuron membrane

• Protein molecules entering the neuron

What happens during repolarization of an action potential?

• Potassium ions rush out of the cell

• Sodium channels start to close

• The neuron becomes hyperpolarized

• The ion concentrations go back to resting levels

What is the size of an action potential in a nerve cell?

• Always the same

• Varies depending on the stimulus

• Bigger for larger neurons

• Smaller for smaller neurons

What is the principle of action potentials in neurons?

• All or none

• Gradual increase

• Proportional to stimulus intensity

• Dependent on ion concentrations