Cell Neuro SI Exam 1 Review F24

The all-or-none principle of nerve action states that

• the entire length of the nerve conducts an action potential or no part does.

• an action potential always reaches its maximum strength or it doesn't appear at all.

• all available ions contribute to the rise and fall of the action potential or none do.

• all synapses on a neuron must be active in order for them to excite it.

The rapid depolarization of an axonal membrane during the rising phase of the action potential is due to

• an increase in sodium resistance.

• an increase in sodium connectance.

• an increase in the sodium equilibrium potential.

• an increase in sodium conductance.

The refractory period occurs because

• sodium and potassium concentrations must be restored, and the "battery" recharged, before another action potential can be generated.

• voltage-gated channels become inactivated for a short time following an action potential.

• pre-synaptic inhibition prevents over-firing and cellular exhaustion.

• the neuron cannot fire again until the membrane potential returns to below threshold.

Which of the following is a function of astrocytes?

• Produce cerebrospinal fluid

• secrete growth factors

• transport newly synthesized proteins

• line the external surfaces of CNS

Can an action potential be properly conducted if we removed the myelin sheaths of a previously myelinated axon?

• No, because an axon can only conduct action potentials if it is myelinated

• Yes, the axon can still conduct an action potential but it would be slower

• No, because a previously myelinated axon is structurally different from an unmyelinated axon

• Yes, because myelin is not responsible for action potential conduction

Tampering with which of the following would affect a neuron's resting membrane potential?

• Voltage gated channels, because they affect how depolarized the cell can get

• Leaky channels, because they affect ion permeability

• Ligand gated channels, because they allow neurotransmitter binding

• Mechanically gated channels, because they respond to membrane stretching

The Nernst equation calculates the equilibrium potential of an ion by considering:

• Concentrations of the ion both inside and outside the cell

• The action potential threshold of the cell

• The permeability of the ion to the cell

• The electrical charge of the ion

What non-myelinating function do Schwann cells provide?

• Structural support-- hold nerves in place

• Providing nutrients-- circulate CSF

• Clear debris-- phagocytosis

• Maintain ionic concentrations-- take up ions

What part of the neuron is considered the main integrative component?

• Dendrites

• Soma

• Axon Hillock

• Axon

• Axon Terminal

Which of the following macroglia is INCORRECTLY

matched with its function

• Oligodendrocytes: CNS myelin formation

• Radial Glia: regulates CSF production/composition

• Schwann Cells: PNS myelin formation

• Astrocytes: general homeostatic maintenance