Exam 1- 276

Which type of glial cell is responsible for forming the myelin sheath in the peripheral nervous system?

• Oligodendrocytes

• Astrocytes

• Radial Glia

• Schwann cells

If a neuron’s membrane potential changes from the resting potential of -70 mV to +30 mV during depolarization, how will the driving forces on Na⁺ and K⁺ be affected?

• The driving force on Na⁺ into the cell will increase, and the driving force on K⁺ outside of the cell will decrease.

• Both Na⁺ and K⁺ will experience a decreased driving force out of the cell.

• Both Na⁺ and K⁺ will experience a increased driving force out of the cell.

• The driving force on Na⁺ into the cell will be decreased, and the driving force on K⁺ out of the cell will increase.

When a neuron's membrane potential repolarizes from +20 mV to -65 mV, how does the relative driving force on Na⁺ change?

• It increases because the membrane potential moves further from ENa⁺

• It decreases because membrane potential moves further to ENa⁺.

• It stays the same

• It fluctuates randomly with each action potential.

The Goldman-Hodgkin-Katz equation is used to determine:

• The equilibrium potential of a single ion

• The membrane potential considering multiple ions

• The rate of synaptic transmission

• The speed of action potential propagation

Which of the following best describes ionotropic receptors?

• They activate second messenger pathways to modulate cellular activity.

• They directly mediate fast synaptic transmission by opening ion channels.

• They require G-protein activation to influence ion channel function.

• They primarily function by altering gene transcription over long periods.

What triggers the closing of the activation gate in voltage-gated sodium channels?

• The resting potential of -70 mV
  

• Depolarization of the membrane

• Repolarization/Hyperpolarization

• Threshold

True or false: Inward current refers to the flow of ions into the cell

• True

• False

Which of the following is NOT a characteristic of action potentials?

• They are all-or-nothing events

• They can travel long distances without losing strength

• Their speed is dependent on axon diameter and myelination

• They vary in amplitude depending on stimulus strength

Why do some axons conduct signals faster than others?

• Smaller axons are faster due to higher resistance and lack of myelination.

• Smaller diameter axons are faster because they require less energy to transmit signals

• Slower axons have more synapses, which delay signal transmission.

• Larger diameter and myelination reduce resistance and increase conduction speed.

Why do nodes of Ranvier exist along myelinated axons?

• They provide structural reinforcement to the axon.

• They act as barriers that slow conduction speed.

• They allow Na+ and K+ channels to regenerate the action potential.

• They increase membrane resistance to reduce ion leakage.