Chp. 11: Fundamentals of the Nervous System and Nervous Tissue

________ are found in the CNS and bind axons and blood vessels to each other.

Astrocytes

Which of the following is correct relative to Ohm's law? A) I = R / V B) Current is directly proportional to the voltage. C) R = V + I D) The more intense the stimulus, the more voltage changes.

B) Current is directly proportional to the voltage.

Strong stimuli cause the amplitude of action potentials generated to increase.

FALSE

________ is a disease that gradually destroys the myelin sheaths of neurons in the CNS, particularly in young adults.

Multiple sclerosis (MS)

The oligodendrocytes can myelinate several axons.

TRUE

Unipolar neurons have axons structurally divided into peripheral and central processes.

TRUE

That part of the nervous system that is voluntary and conducts impulses from the CNS to the skeletal muscles is the ________ nervous system.

somatic

When one or more presynaptic neurons fire in rapid order it produces a much greater depolarization of the postsynaptic membrane than would result from a single EPSP; this event is called ________ summation.

temporal

Which of these ions is actively transported through the cell membrane to establish a resting potential? A) Na B) Cl C) Mg D) Ca

A) Na

Select the correct statement about serial processing. A) Spinal reflexes are an example of serial processing. B) Input travels along several different pathways. C) Smells are processed by serial pathways. D) Memories are triggered by serial processing.

A) Spinal reflexes are an example of serial processing.

Neuroglia that control the chemical environment around neurons by buffering potassium and recapturing neurotransmitters are ________. A) astrocytes B) oligodendrocytes C) microglia D) Schwann cells

A) astrocytes

The part of a neuron that conducts impulses away from its cell body is called a(n) ________. A) axon B) dendrite C) neurolemma D) Schwann cell

A) axon

Ciliated CNS neuroglia that play an active role in moving the cerebrospinal fluid are called ________. A) ependymal cells B) Schwann cells C) oligodendrocytes D) astrocytes

A) ependymal cells

An action potential ________. A) is essential for impulse propagation B) involves the influx of negative ions to depolarize the membrane C) is initiated by potassium ion movement D) involves impulse propagation dependent on chemically gated ion channels

A) is essential for impulse propagation

The sodium-potassium pump ________. A) pumps three sodium ions outside the cell and two potassium ions inside B) pumps two sodium ions outside the cell and three potassium ions inside C) pumps three sodium ions inside the cell and two potassium ions outside D) pumps two sodium ions inside the cell and three potassium ions outside

A) pumps three sodium ions outside the cell and two potassium ions inside

Which of the following is not a structural feature of a neuron? A) synaptic cleft B) Nissl bodies C) dendrites D) axon

A) synaptic cleft

A second nerve impulse cannot be generated until ________. A) the membrane potential has been reestablished B) the Na ions have been pumped back into the cell C) proteins have been resynthesized D) all sodium gates are closed

A) the membrane potential has been reestablished

Saltatory conduction is made possible by ________. A) the myelin sheath B) large nerve fibers C) diphasic impulses D) erratic transmission of nerve impulses

A) the myelin sheath

Which of the following is true about the movement of ions across excitable living membranes? A) Ions always move actively across membranes through leakage channels. B) Some ions are prevented from moving down their concentration gradients by ATP-driven pumps. C) Sodium gates in the membrane can open in response to electrical potential changes. D) The bulk of the solutions inside a cell are negatively charged.

B) Some ions are prevented from moving down their concentration gradients by ATP-driven pumps.

Choose the statement that is most correct about membrane potential. A) Voltage would be measured by placing two electrodes on the exterior of the axon. B) Voltage would be measured by placing one electrode inside the membrane and another outside the membrane. C) Voltage would be measured by placing one electrode on one end of the axon and another electrode on the other end. D) Voltage would be measured by placing one electrode on the axon and grounding the other electrode.

B) Voltage would be measured by placing one electrode inside the membrane and another outside the membrane.

The part of the neuron that normally receives stimuli is called ________. A) an axon B) a dendrite C) a neurolemma D) a Schwann cell

B) a dendrite

An inhibitory postsynaptic potential (IPSP) is associated with ________. A) a change in sodium ion permeability B) hyperpolarization C) opening of voltage-regulated channels D) lowering the threshold for an action potential to occur

B) hyperpolarization

In what way does the interior surface of a cell membrane of a resting (nonconducting) neuron differ from the external environment? The interior is ________. A) positively charged and contains less sodium B) negatively charged and contains less sodium C) negatively charged and contains more sodium D) positively charged and contains more sodium

B) negatively charged and contains less sodium

The point at which an impulse from one nerve cell is communicated to another nerve cell is the ________. A) cell body B) synapse C) receptor D) effector

B) synapse

The chemically gated channel, NMDA, allows ________ ions entry into the nerve cell. A) Na+ B) K+ C) Ca2+ D) Cl-

C) Ca2+

Neurons may be classified according to several characteristics. Which of the following is correct? A) Group A fibers are mostly somatic sensory and motor and are the smallest in diameter. B) Group B fibers are highly myelinated and have the highest conduction velocities. C) Group C fibers are not capable of saltatory conduction. D) A small cross-sectional area allows shorter conduction times.

C) Group C fibers are not capable of saltatory conduction.

________ is an indolamine. A) Dopamine B) Epinephrine C) Serotonin D) Tyrosine

C) Serotonin

An excitatory neurotransmitter secreted by motor neurons innervating skeletal muscle is ________. A) cholinesterase B) norepinephrine C) acetylcholine D) gamma aminobutyric acid

C) acetylcholine

A neuron that has as its primary function the job of connecting other neurons is called a(n) ________. A) efferent neuron B) afferent neuron C) association neuron D) glial cell

C) association neuron

The sympathetic and parasympathetic are subdivisions of the ________. A) central nervous system B) voluntary nervous system C) autonomic nervous system D) somatic nervous system

C) autonomic nervous system

The term central nervous system refers to the ________. A) autonomic nervous system B) brain, spinal cord, and peripheral nerves C) brain and spinal cord D) spinal cord and spinal nerves

C) brain and spinal cord

A neuronal circuit that concentrates or directs a large number of incoming impulses to a rather small number of neurons is called a(n) ________. A) diverging circuit B) oscillating circuit C) converging circuit D) parallel circuit

C) converging circuit

The role of acetylcholinesterase is to ________. A) act as a transmitting agent B) amplify or enhance the effect of ACh C) destroy ACh a brief period after its release by the axonal endings D) stimulate the production of serotonin

C) destroy ACh a brief period after its release by the axonal endings

Collections of nerve cell bodies outside the central nervous system are called ________. A) nuclei B) nerves C) ganglia D) tracts

C) ganglia

Which group of fibers spreads impulses at up to 1 meter per second? A) group A fibers B) group B fibers C) group C fibers D) group D fibers

C) group C fibers

All of the following are true of graded potentials except that they ________. A) are short-lived B) can form on receptor endings C) increase amplitude as they move away from the stimulus point D) can be called postsynaptic potentials

C) increase amplitude as they move away from the stimulus point

The sheath of Schwann is also called the ________. A) myelin sheath B) axolemma C) neurilemma D) white matter

C) neurilemma

The substance released at axon terminals to propagate a nervous impulse is called a(n) ________. A) ion B) cholinesterase C) neurotransmitter D) biogenic amine

C) neurotransmitter

Schwann cells are functionally similar to ________. A) ependymal cells B) microglia C) oligodendrocytes D) astrocytes

C) oligodendrocytes

Direct-acting neurotransmitters ________. A) require cyclic AMP B) mediate very slow responses C) open ion channels to provoke rapid responses D) act through second messengers

C) open ion channels to provoke rapid responses

A neural circuit in which a single impulse is transmitted over and over is a ________. A) diverging circuit B) converging circuit C) reverberating circuit D) repetitive circuit

C) reverberating circuit

If a motor neuron in the body were stimulated by an electrode placed about midpoint along the length of the axon ________. A) the impulse would move to the axon terminal only B) muscle contraction would occur C) the impulse would spread bidirectionally D) the impulse would move to the axon terminal only, and the muscle contraction would occur

C) the impulse would spread bidirectionally

Which of the following will occur when an excitatory postsynaptic potential (EPSP) is being generated on the dendritic membrane? A) Specific sodium gates will open. B) Specific potassium gates will open. C) Sodium gates will open first, then close as potassium gates open. D) A single type of channel will open, permitting simultaneous flow of sodium and potassium.

D) A single type of channel will open, permitting simultaneous flow of sodium and potassium.

Select the correct statement about synapses. A) Cells with interconnected cytoplasm are chemically coupled. B) The release of neurotransmitter molecules gives cells the property of being electrically coupled. C) Neurotransmitter receptors are located on the axons of cells. D) The synaptic cleft prevents an impulse from being transmitted directly from one neuron to another.

D) The synaptic cleft prevents an impulse from being transmitted directly from one neuron to another.

The period after an initial stimulus when a neuron is not sensitive to another stimulus is the ________. A) resting period B) repolarization C) depolarization D) absolute refractory period

D) absolute refractory period

Nerve cell adhesion molecules (N-CAMs) ________. A) release nerve growth factor B) are found on "pathfinder" neurons C) are crucial in the production of neurotransmitters D) are crucial for the development of neural connections

D) are crucial for the development of neural connections

Bipolar neurons are commonly ________. A) motor neurons B) called neuroglial cells C) found in ganglia D) found in the retina of the eye

D) found in the retina of the eye

When a sensory neuron is excited by some form of energy, the resulting graded potential is called a(n) ________. A) postsynaptic potential B) excitatory potential C) action potential D) generator potential

D) generator potential

Ependymal cells ________. A) are a type of neuron B) are a type of macrophage C) are the most numerous of the neuroglia D) help to circulate the cerebrospinal fluid

D) help to circulate the cerebrospinal fluid

Which of the following is not a function of the autonomic nervous system? A) innervation of smooth muscle of the digestive tract B) innervation of cardiac muscle C) innervation of glands D) innervation of skeletal muscle

D) innervation of skeletal muscle

Which of the following is a good example of a neuromodulator? A) acetylcholine B) any protein C) any carbohydrate D) nitric oxide

D) nitric oxide

Immediately after an action potential has peaked, which cellular gates open? A) sodium B) chloride C) calcium D) potassium

D) potassium

A positive feedback cycle is the main force in the generation of graded potentials at receptor ends.

FALSE

Action potentials can be generated by virtually all cells of the body because all cells possess cell membranes.

FALSE

Neurons that are far away from the center of the neuron pool and that are not easily excited by an incoming stimulus are in the discharge zone.

FALSE

Saltatory conduction occurs because of the presence of salt (NaCl) around the neuron.

FALSE

The all-or-none phenomenon as applied to nerve conduction states that the whole nerve cell must be stimulated for conduction to take place.

FALSE

The nodes of Ranvier are found only on myelinated, peripheral neural processes.

FALSE

The two major classes of graded potentials are transmitter potentials and receptor potentials.

FALSE

________ is a neurotransmitter of the CNS that is used by Purkinje cells of the CNS.

GABA (gamma aminobutyric acid)

________ potentials are short-lived, local changes in membrane potential that can be either depolarized or hyperpolarized.

Graded

________ law is the relationship between voltage, current, and resistance.

Ohm's

A graded potential that is the result of a neurotransmitter released into the synapse between two neurons is called a postsynaptic potential.

TRUE

A stimulus traveling toward a synapse appears to open calcium channels at the presynaptic end, which in turn promotes fusion of synaptic vesicles to the axonal membrane.

TRUE

A synapse formed between the axon ending of one neuron and the cell body of another neuron is called an axosomatic synapse.

TRUE

Acetylcholine is not a biogenic amine.

TRUE

Cell bodies of sensory neurons may be located in ganglia lying outside the central nervous system.

TRUE

During depolarization, the inside of the neuron's membrane becomes less negative.

TRUE

Efferent nerve fibers may be described as motor nerve fibers.

TRUE

Enkephalins and endorphins are peptides that act like morphine.

TRUE

If bacteria invaded the CNS tissue, microglia would migrate to the area to engulf and destroy them.

TRUE

In myelinated axons the voltage-regulated sodium channels are concentrated at the nodes of Ranvier.

TRUE

Large-diameter nerve fibers conduct impulses much faster than small-diameter fibers.

TRUE

Myelination of the nerve fibers in the central nervous system is the job of the oligodendrocyte.

TRUE

Neurons in the CNS are organized into functional groups.

TRUE

Reflexes are rapid, automatic responses to stimuli.

TRUE

Voltage is always measured between two points and may be called the potential between these two points.

TRUE

The synapse more common in embryonic nervous tissue than in adults is the ________.

electrical synapse

A gap between Schwann cells in the peripheral system is called a(n) ________.

node of Ranvier

When information is delivered within the CNS simultaneously by different parts of the neural pathway, the process is called ________ processing.

parallel