Chapter 12 Quiz: Neural Tissue

Which of the following is not a function of the nervous system?

direct long-term functions, such as growth

After acetylcholinesterase acts, the synaptic terminal

reabsorbs the choline

Figure 12-2 The Nerve Action Potential
Use Figure 12-2 to answer the following questions:
What is occurring in the area between #2 and #3?

Sodium ions are entering the axon and causing depolarization.

EPSPs (excitatory postsynaptic potentials) occur when

extra sodium ions enter a cell

The following are the steps involved in transmission at a cholinergic synapse. What is the correct sequence for these events?

1. Chemically-gated sodium channels on the postsynaptic membrane are activated.
2. Calcium ions enter the synaptic terminal.
3. Acetylcholinesterase hydrolyzes acetylcholine.
4. An action potential depolarizes the synaptic terminal at the presynaptic membrane.
5. The pre-synaptic terminal reabsorbs choline.
6. Acetylcholine is released from storage vesicles by exocytosis.
7. Acetylcholine binds to receptors on the postsynaptic membrane.
8. Calcium ions are removed from the cytoplasm of the pre-synaptic terminal.

4, 2, 6, 7, 1, 8, 3, 5

The following are the main steps in the generation of an action potential.

1. Sodium channels are inactivated.
2. Voltage-gated potassium channels open and potassium moves out of the cell, initiating repolarization.
3. Sodium channels regain their normal properties.
4. A graded depolarization brings an area of an excitable membrane to threshold.
5. A temporary hyperpolarization occurs
   .6. Sodium channel activation occurs.7. Sodium ions enter the cell and depolarization occurs.
   What is the proper sequence of these events?

4, 6, 7, 1, 2, 3, 5

Sensory neurons of the PNS are

unipolar

Figure 12-2 The Nerve Action Potential
Use Figure 12-2 to answer the following questions:
Which area of the graph shows when potassium channels open?

3

Figure 12-2 The Nerve Action Potential
Use Figure 12-2 to answer the following questions:
What is occurring at the area labeled #4?

Excessive potassium has diffused out causing hyperpolarization.

Ions can move across the plasma membrane in which of the following ways?

through passive or leak channels
through chemically gated channels as in neuromuscular transmission
by ATP-dependent ion pumps like the sodium-potassium exchange pump
through voltage-gated channels as in the action potential

Figure 12-2 The Nerve Action Potential
Use Figure 12-2 to answer the following questions:
Which area of the graph shows when voltage-gated sodium channels are open?

2

Figure 12-2 The Nerve Action Potential
Use Figure 12-2 to answer the following questions:
Which area of the graph shows when chemically gated sodium channels are open?

1

If the permeability of a resting axon to sodium ion increases,

inward movement of sodium will increase and the membrane will depolarize

Figure 12-1 The Neuron
Use Figure 12-1 to answer the following questions:
Which part(s) of the neuron can propagate an action potential?

3

Opening of sodium channels in the axon membrane causes

depolarization