Chapter 12

Which of he following statements are TRUE? (1) If the excitatory effect is greater than the inhibitory effect but less than the threshold of stimulation, the result is a subthreshold EPSP. (2) If the excitatory effect is greater than the inhibitory effect and reaches or surpasses the threshold level of stimulation, the result is a threshold or suprathreshold EPSP and one or more nerve impulses. (3) If the inhibitory effect is greater than the excitatory effect, the membrane hyperpolarizes, resulting in inhibition of the postsynaptic neuron and the inability of the neuron to generate a nerve impulse. (4) The greater the summation of hyperpolarizations, the more likely a nerve impulse will be initiated.

1, 2, & 3

Which of the following statements are true? (1) The frequency of impulses and number of activated sensory neurons encode differences in stimuli intensity. (2) Larger-diameter axons conduct nerve impulses faster than smaller-diameter ones. (3) Continuous conduction is faster than saltatory conduction. (4) The presence or absence of a myelin sheath is an important factor that determines the speed of nerve impulse propagation. (5) Action potentials are localized, but graded potentials are propagated.

1, 2, & 4

Which of the following statements are TRUE? (1) The sensory function of the nervous system involves sensory receptors sensing certain changes in the internal and external environments. (2) Sensory neurons receive electrical signals from sensory receptors. (3) The integrative function of the nervous system involves analyzing sensory information, storing some of it, and making decisions regarding appropriate responses. (4) Interneurons are located primarily in the PNS. (5) Motor function involves the activation of effectors (muscles and glands).

1, 2, 3, & 5

Which of the following statements are TRUE? (1) The basic types of ion channels are gated, leakage, and electrical. (2) Ion channels allow for the development of graded potentials and action potentials. (3) Voltage-gated channels open in response to changes in the membrane potential. (4) Ligand-gated channels open due to the presence of specific chemicals. (5) A graded potential is useful for communication over long distances.

2, 3, & 4

Neurotransmitters are removed from the synaptic cleft by: (1) Axonal transport (2) Diffusion away from the cleft (3) Neurosecretory cells (4) Enzymatic breakdown (5) Cellular uptake

2, 4, & 5

Place the following events in a chemical synapse in the correct order: (1) Release of neurotransmitters into the synaptic cleft. (2) Arrival of nerve impulse at the presynaptic neuron's synaptic end bulb (or varicosity). (3) Either depolarization or hyperpolarization of postsynaptic membrane. (4) Inward flow of Ca2+ through activated voltage-gated Ca2+ channels in the synaptic end bulb membrane. (5) Exocytosis of synaptic vesicles. (6) Opening of ligand-gated channels on the postsynaptic plasma membrane. (7) Binding of neurotransmitters to receptors in the postsynaptic neuron's plasma membrane.

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

A neuron's resting membrane potential is established and maintained by: (1) A high concentration of K+ in the extracellular fluid and a high concentration of Na+ in the cytosol. (2) The plasma membrane's higher permeability to Na + because of the presence of numerous Na+ leakage channels. (3) Differences in both ion concentrations and electrical gradients. (4) The fact that there are numerous large, nondiffusible anions in the cytosol. (5) Sodium-potassium pumps that help to maintain the proper distribution of sodium and potassium.

3, 4, & 5

Several neurons in the brain sending impulses to a single motor neuron that terminates at a neuromuscular junction is an example of a blank circuit.

Converging

T/F: At a chemical synapse between two neurons, the neuron receiving the signal is called the presynaptic neuron, and the neuron sending the signal is called the postsynaptic neuron.

False

T/F: Neurons in the PNS are always capable of repair while those in the CNS are not.

False

The subdivisions of the PNS are the blank, blank, and blank.

Somatic, Autonomic, Enteric

The two divisions of the autonomic nervous system are the blank division and the blank division.

Sympathetic, Parasympathetic