Nerve Cell Membrane and Ion Movement

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What ion channels are primarily responsible for maintaining the resting membrane potential in neurons?

potassium channels

What is the primary reason sodium ions cannot diffuse through the membrane in a resting nerve cell?

sodium channels are closed

What is the threshold value for an electrical stimulus to produce an action potential?

-50 mV

What occurs during the first stage of an action potential?

depolarization due to Na+ channels opening Signup and view all the answers

What is the result of applying a weak stimulus to an axon?

no significant axon potential changes occur beyond a few millimeters Signup and view all the answers

What process occurs during the final phase of an action potential?

Na+/K+ pump activation Signup and view all the answers

What is the function of the myelin sheaths in myelinated neurons?

To increase the speed of nerve impulse transmission Signup and view all the answers

What is the purpose of the lipid bilayer in the plasma membrane of an axon?

To act as an insulator, separating the internal and external conducting fluids Signup and view all the answers

How do unmyelinated neurons transmit nerve impulses compared to myelinated neurons?

Slower, without the node of Ranvier Signup and view all the answers

What components of an electrical circuit are similar to the axon's function?

Wires and resistors Signup and view all the answers

What is the role of synapses in a neuron?

To receive electrical messages from other neurons Signup and view all the answers

What is the function of the axoplasm in the axon?

To act as a conducting fluid Signup and view all the answers

What is the role of myelin in the conduction of action potentials along an axon?

Myelin acts as an insulator, preventing current from leaving the axon, thus increasing the speed of action potential conduction. Signup and view all the answers

What happens to the conduction of an action potential in unmyelinated axons?

Action potential conduction slows because current leaks from previously insulated axon areas. Signup and view all the answers

What is the function of the node of Ranvier in action potential conduction?

The node of Ranvier is a non-myelinated area where action potentials can jump from node to node. Signup and view all the answers

How do Schwann cells contribute to the formation of the myelin sheath?

Schwann cells form the myelin sheath by wrapping the axon many times with sheet-like membrane extensions. Signup and view all the answers

What is the importance of the resistance of the axon to current in action potential conduction?

The resistance of the axon to current affects the speed of action potential conduction, with higher resistance increasing the speed. Signup and view all the answers

What is the relationship between the myelin sheath and the propagation of action potentials?

The myelin sheath allows action potentials to jump from node to node, increasing the speed of conduction. Signup and view all the answers