Nervous system

Which neuroglia cell does not belong in the CNS?

• satellite cells

• astrocytes

• microglial cell

• ependymal cell

How does an action potential propagate down a myelinated axon?

Why do neurons have a negative resting membrane potential?

Answer explanation

1. resting membrane is impermeable to the large anionic cytoplasmic proteins

2. cell membrane is 75-100x more permeable to K+ than to Na+ (more positive charges are moving out than in)

3. Na+/K+ Pump: pumps 3 Na+ out for every 2 K+ maintains gradients (indirectly stabilizing the resting membrane potential)

True or false potassium is low on the outside?

• True

• Flase

True or false Sodium is high on the inside?

• True

• False

What is the resting membrane potential?

• -40mV

• 70mV

• -55mV

• -70mV

List and describe the 4 channels

Answer explanation

Passive (leaky) channels: always open just diffusion across the membrane

Chemically gated channels: open and close in response to chemicals, such as neurotransmitters

Mechanical gated channels: open and close in response to mechanical vibration or pressure, such as sound waves or the pressure of touch

Voltage gated channels: open and close in response to changes in transmembrane voltage

What is the structural classification of number 4 in the picture?

• multipolar

• bipolar

• unipolar

• anaxonic neuron

What is a bundle of neuronal processes in the PNS called?

• nerve

• tract

• neuron

• nuclei

Define Tract

Answer explanation

Bundle of neuronal processes in the CNS