Chapter 12 Assignment

Encoding stimulus strength depends on which of the following? Check all that apply. 1. Different neurons have the same threshold of excitation. 2. The more strongly a neuron is stimulated, the less frequently it fires. 3. Different neurons have different thresholds of excitation. 4. The more strongly a neuron is stimulated, the more frequently it fires.

- Different neurons have different thresholds of excitation. - The more strongly a neuron is stimulated, the more frequently it fires.

Why is myelin important? Check all that apply. 1. It forms extensions called perivascular feet, which contact the blood capillaries and stimulate them to form a tight seal called the blood-brain barrier. 2. It speeds up signal conduction in the nerve fiber. 3. It produces cerebrospinal fluid. 4. It is formed to assist in the regeneration of damaged fibers. 5. It insulates the nerve fiber.

- It speeds up signal conduction in the nerve fiber. - It is formed to assist in the regeneration of damaged fibers. - It insulates the nerve fiber.

True or False. Acetylcholine is actively transported from the presynaptic membrane to the postsynaptic membrane.

False

True or False. Receptors that bind the neurotransmitter at the postsynaptic cell membrane are voltage-gated.

False

Acetylcholine has which effect on the postsynaptic neuron? 1. Ligand-gated calcium ion channels open and calcium diffuses in. 2. Ligand-gated sodium ion channels open and sodium diffuses in. 3. Terminal vessels migrate to the plasma membrane. 4. Voltage-gated calcium ion channels open and calcium diffuses in. 5. Voltage-gated sodium ion channels open and sodium diffuses in.

Ligand-gated sodium ion channels open and sodium diffuses in.

Why does depolarization occur? 1. More K+ diffuse into the cell than Na+ diffuse out of it. 2. More K+ diffuse out of the cell than Na+ diffuse into it. 3. More Na+ diffuse into the cell than K+ diffuse out of it. 4. More Na+ diffuse out of the cell than K+ diffuse into it. 5. Both Na+ and K+ diffuse into the cell.

More Na+ diffuse into the cell than K+ diffuse out of it.

During depolarization, which of the following statements about voltage-gated ion channels is true? 1. K+ gates open before Na+ gates. 2. Na+ gates open before K+ gates. 3. Na+ and K+ gates open at the same time. 4. K+ gates open while Na+ gates remain closed.

Na+ gates open before K+ gates.

Place each label in the proper position to designate the organ system it describes. 1. Nervous 2. Endocrine 1. slower communication 2. basic life support (breathing regulation) 3. electrical 4. gamete (sex cell) production 5. blood transport 6. utilizes hormones 7. chemical only 8. growth 9. faster communication 10. cell-to-cell communication

Nervous - faster communication - electrical - cell-to-cell communication - basic life support (breathing regulation) Endocrine - slower communication - chemical only - blood transport - utilizes hormones - growth - gamete (sex cell) production

Which of the following statements about the resting membrane potential is true? 1. The exterior of the cell has a net negative charge and the interior has a net positive charge. 2. The exterior of the cell has a net negative charge and the interior is neutral. 3. The exterior of the cell has a net positive charge and the interior has a net negative charge. 4. The exterior of the cell has a net positive charge and the interior is neutral. 5. The exterior of the cell is neutral, and the interior has a net negative charge.

The exterior of the cell has a net positive charge and the interior has a net negative charge.

True or False. If the postsynaptic membrane potential reaches threshold level, an action potential will be produced.

True

True or False. The area between the presynaptic nerve cell and the postsynaptic muscle cell is termed the synaptic cleft.

True

True or False. The nerve impulse is an electrical current that travels along dendrites or axons.

True

True or False. The sodium-potassium pump is involved in establishing the resting membrane potential.

True

An action potential arriving at the presynaptic terminal causes what to occur? 1. Voltage-gated sodium ion channels open, and sodium ions diffuse into the cell. 2. Voltage-gated sodium ion channels open, and sodium ions diffuse out of the cell. 3. Voltage-gated calcium ion channels open, and calcium ions diffuse into the cell. 4. Acetylcholine diffuses into the cell. 5. Ligand-gated sodium channels open, and sodium ions diffuse out of the cell.

Voltage-gated calcium ion channels open, and calcium ions diffuse into the cell.

The primary neurotransmitter at the neuromuscular junction is __________. 1. dopamine 2. adrenaline 3. acetylcholine 4. histamine 5. serotonin

acetylcholine

Place the following labels in the proper position to designate what effect each condition would have on membrane physiology. 1. makes RMP less negative 2. influence the ability of the cell to repolarize 3. influences the ability of the cell to depolarize 1. acetylcholine esterase concentration is decreased 2. the size the synaptic cleft is increased 3. neurotransmitter synthesis is compromised due to Golgi dysfunction in the pre-synaptic neuron 4. release of excitatory neurotransmitter input is blocked 5. ATP stores are declining through mitochondrial poison (arsenic) 6. voltage-regulated potassium channels are blocked 7. hypothermia (low ECF sodium) 8. hyperhydration (high water concentration in ECF) 9. decreased concentration of leaky potassium channels in the membrane 10. increased concentration of leaky sodium channels in the membrane

makes RMP less negative - ATP stores are declining through mitochondrial poison (arsenic) - decreased concentration of leaky potassium channels in the membrane - increased concentration of leaky sodium channels in the membrane influence the ability of the cell to repolarize - acetylcholine esterase concentration is decreased - voltage-regulated potassium channels are blocked influences the ability of the cell to depolarize - the size the synaptic cleft is increased - neurotransmitter synthesis is compromised due to Golgi dysfunction in the pre-synaptic neuron - release of excitatory neurotransmitter input is blocked - hypothermia (low ECF sodium) - hyperhydration (high water concentration in ECF)

Arrange the following in the order in which they occur at the postsynaptic side of a neuromuscular junction: 1. An action potential is propagated over the muscle cell membrane 2. Depolarization of the postsynaptic membrane 3. Sodium ions move into muscle cell 1. 1, 2, 3 2. 2, 1, 3 3. 2, 3, 1 4. 3, 2, 1 5. 3, 1, 2

3, 2, 1

What are the three general classes of neurons that correspond to the three major aspects of nervous system function? Check all that apply. 1. Motor neurons that send signals predominantly to muscle and gland cells. 2. Schwann cells that envelop nerve fibers of the PNS. 3. Interneurons that lie between, and interconnect the incoming sensory pathways and the outgoing motor pathways of the CNS. 4. Sensory neurons that are specialized to detect stimuli such as light, heat, pressure, and chemicals, and transmit information about them to the CNS. 5. Ependymal cells that produce cerebral spinal fluid.

- Motor neurons that send signals predominantly to muscle and gland cells. - Interneurons that lie between, and interconnect the incoming sensory pathways and the outgoing motor pathways of the CNS. - Sensory neurons that are specialized to detect stimuli such as light, heat, pressure, and chemicals, and transmit information about them to the CNS.

Select the accurate statement(s) regarding the divisions of the nervous system. Choose all that apply. 1. The sympathetic division tends to arouse the body for action. 2. The visceral motor division (autonomic nervous system) carries signals to glands, skeletal muscle, and smooth muscle. 3. The somatic motor division carries signals to the somas of the neurons. 4. The parasympathetic division tends to have a calming effect. 5. The central nervous system has both a motor and sensory division.

- The sympathetic division tends to arouse the body for action. - The parasympathetic division tends to have a calming effect.

Place a single word into each sentence to make it correct, describing the repair of a peripheral nerve fiber. 1. A damaged ____________ nerve fiber may regenerate if its soma is intact and some neurilemma remains. 2. When a nerve fiber is cut, the fiber distal to the injury ____________ survive. 3. Near the site of injury, the basal lamina and the neurilemma form a ____________ tube. 4. The tube guides the growing sprout back to the original target cells, reestablishing ____________ contact. 5. When contact is established, the ____________ shrinks and reinnervated muscle fibers regrow. 1. synaptic 2. lamina 3. peripheral 4. cannot 5. unmyelinated 6. regeneration 7. soma 8. can

1. A damaged peripheral nerve fiber may regenerate if its soma is intact and some neurilemma remains. 2. When a nerve fiber is cut, the fiber distal to the injury cannot survive. 3. Near the site of injury, the basal lamina and the neurilemma form a regeneration tube. 4. The tube guides the growing sprout back to the original target cells, reestablishing synaptic contact. 5. When contact is established, the soma shrinks and reinnervated muscle fibers regrow.

Place the following structures in the order that an electrical impulse would travel beginning with the post-synaptic membrane. 1. axon terminals 2. dendrites 3. node of ranvier 4. axon hillock 5. terminal arborization 6. soma 7. internode

1. dendrite 2. soma 3. axon hillock 4. internode 5. node of ranvier 6. terminal aborization 7. axon terminals

Place each label in the proper position to designate the appropriate glial cell. 1. Oligodendrocytes 2. Ependymal Cells 3. Microglia 4. Astrocytes 5. Schwann Cells 6. Satellite Cells 1. surround and insulate cells of the PNS and found around the somas 2. produce and circulate CSF 3. multi-functioning cell involved with neurogenesis, scar formation, etc. 4. form the myelin sheath in the CNS 5. insulate neurons and enhance the rate of transmission in the PNS 6. most abundant CNS glial cells 7. macrophages of the CNS 8. form the myelin sheath in the PNS 9. ciliated cells resembling epithelium

Oligodendrocytes - form the myelin sheath in the CNS Ependymal Cells - ciliated cells resembling epithelium - produce and circulate CSF Microglia - macrophages of the CNS Astrocytes - most abundant CNS glial cells - multi-functioning cell involved with neurogenesis, scar formation, etc. Schwann Cells - form the myelin sheath in the PNS - insulate neurons and enhance the rate of transmission in the PNS Satellite Cells - surround and insulate cells of the PNS and found around the somas

What happens as a result of ion flow at a presynaptic terminal? 1. Synaptic vesicles migrate to the plasma membrane and release acetylcholine. 2. Acetylcholine is passively transported from the presynaptic neuron. 3. Acetylcholine is actively transported to the postsynaptic neuron. 4. Ligand-gated sodium channels open. 5. Sodium ions diffuse into the cell.

Synaptic vesicles migrate to the plasma membrane and release acetylcholine.

Place the following labels in the proper position to designate action potential or local potential. 1. action potentials 2. local potentials 3. both 1. voltage-regulated potassium channels 2. ligand-regulated sodium channels 3. reversible 4. important for transmission over long distances 5. cause summation 6. voltage-regulated sodium channels 7. require threshold 8. rate of transmission is increased with myelination 9. decremental 10. sodium-potassium ATPase pumps work to re-establish RMP

action potentials - voltage-regulated potassium channels - important for transmission over long distances - voltage-regulated sodium channels - require threshold - rate of transmission is increased with myelination local potentials - ligand-regulated sodium channels - reversible - cause summation - decremental both - sodium-potassium ATPase pumps work to re-establish RMP

Pair each type of axonal transport with its definition. 1. anterograde transport 2. slow anterograde transport 3. fast retrograde transport 4. fast anrerograde transport 5. axonal transport 1. movement of enzymes and small molecules toward that distal end of the axon 2. movement of enzymes and cytoskeleton components down the axon to renew worn-out axoplasmic components 3. returns used synaptic vesicles and other materials to the soma 4. two-way passage of proteins, organelles, and other materials along an axon 5. movement down the axon away from the soma

anterograde transport - movement down the axon away from the soma slow anterograde transport - movement of enzymes and cytoskeleton components down the axon to renew worn-out axoplasmic components fast retrograde transport - returns used synaptic vesicles and other materials to the soma fast anrerograde transport - movement of enzymes and small molecules toward that distal end of the axon axonal transport - two-way passage of proteins, organelles, and other materials along an axon