chapter 11 ap

One incoming fiber triggers responses in ever-increasing numbers farther and farther along the circuit.

) Diverging circuit

What function is served by the increased axon diameter at the nodes of Ranvier?

: Increased diameter results in increased surface area on the membrane for sodium channels. This results in increased speed of impulse propagation.

"Feel-good" neurotransmitter.

A) Norepinephrine

Plasma membrane exhibits voltage-gated Na+ and K+ channels.

Conducting region

Different types of sensory input can have the same ultimate effect.

Converging circuit

Principal inhibitory neurotransmitter of the spinal cord.

Glycine

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

Multiple sclerosis (MS)

A patient was admitted for depression. What should the nurse explain to the patient regarding the role of serotonin and depression?

Serotonin is a biogenic amine neurotransmitter widely distributed in the brain, where it plays a role in emotional behavior and helps to regulate the biological clock.

6) Reflexes are rapid, automatic responses to stimuli

T

ATP neurotransmitters have what basic effect on the body?

They provoke a sensation of pain.

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

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

How can potentially poisonous gases like NO and CO be used by the body?

: These gases are neurotransmitters that act indirectly. Similar to hormones, NO and CO promote longer-lasting effects by acting through intracellular second-messenger molecules.

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

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

) The interior of the cell becomes less negative due to an influx of sodium ions.

A) Depolarization

Increases acid secretion in the stomach; blocked by cimetidine.

A) Histamine

An exceptionally strong stimulus can trigger a response______

A) Relative refractory period

Involved in control of rhythmic activities such as breathing.

A) Reverberating circuit

Numerous nerve impulses arriving at a synapse at closely timed intervals exert a cumulative effect.

A) Temporal summation

Which of the following is not true of graded potentials? A) They increase amplitude as they move away from the stimulus point. B) They can form on receptor endings. C) They can be called postsynaptic potentials. D) They are short-lived.

A) They increase amplitude as they move away from the stimulus point.

Area where nerve impulse is generated. ____

A) Trigger zone

The period after an initial stimulus when a neuron is not sensitive to another stimulus is the ________. 11) A) absolute refractory period B) depolarization C) resting period D) repolarization

A) absolute refractory

Which of the following describes the nervous system integrative function? A) analyzes sensory information, stores information, makes decisions B) responds to stimuli by gland secretion or muscle contraction C) senses changes in the environment

A) analyzes sensory information, stores information, makes decisions

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

A) found in the retina of the eye

Ependymal cells ________. 14) A) help to circulate the cerebrospinal fluid B) are a type of neuron C) are the most numerous of the neuroglia D) are a type of macrophage

A) help to circulate the cerebrospinal fluid

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

A) neurilemma

Plasma membrane exhibits voltage-gated Ca2+ channels.

A) secretory region

Collections of nerve cell bodies outside the central nervous system are called ________. 4) A) ganglia B) tracts C) nuclei D) nerves

A)ganglia

What mechanism is responsible for axonal transport?

ATP-dependent "motor" proteins such as kinesin, dynein, and myosin are responsible. They propel cellular components along microtubules.

The neuron cannot respond to a second stimulus, no matter how strong.

Absolute refractory period

Also called a nerve impulse transmitted by axons.

Action potential

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

Astrocytes

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

Astrocytes

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

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

Which of the following is false or incorrect? A) An inhibitory postsynaptic potential occurs if the inhibitory effect is greater than the excitatory, causing hyperpolarization of the membrane. B) A nerve impulse occurs if the excitatory and inhibitory effects are equal. C) An excitatory postsynaptic potential occurs if the excitatory effect is greater than the inhibitory effect but less than threshold.

B) A nerve impulse occurs if the excitatory and inhibitory effects are equal

Which of the following is an excitatory neurotransmitter secreted by motor neurons innervating skeletal muscle? A) norepinephrine B) acetylcholine C) gamma aminobutyric acid D) cholinesterase

B) acetylcholine

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

B) brain and spinal cord

33) What is the role of acetylcholinesterase?A) act as a transmitting agent B) destroy ACh a brief period after its release by the axon endings C) amplify or enhance the effect of ACh D) stimulate the production of serotonin

B) destroy ACh a brief period after its release by the axon endings

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

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) negatively charged and contains more sodium B) negatively charged and contains less sodium C) positively charged and contains more sodium D) positively charged and contains less sodium

B) negatively charged and contains less sodium

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

B) potassium

Which of the following is not a function of astrocytes? A) support and brace neurons B) provide the defense for the CNS C) anchor neurons to blood vessels D) control the chemical environment around neurons E) guide the migration of young neurons, synapse formation, and helping to determine capillary permeability

B) provide the defense for the CNS

Imagine a neuron that has several hundred axonal knobs impinging on it. The majority of these axonal knobs are shown to be "firing." However, the neuron in question does not transmit an impulse. Give a valid explanation of why this could occur.

Both excitatory and inhibitory potentials impinge on neurons. Inhibitory postsynaptic potentials (IPSPs) are "firing," but due to the neurotransmitter released and its action, the postsynaptic neuron is inhibited from "firing" (hyperpolarized).

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) A small cross-sectional area allows shorter conduction times. C) Group C fibers are not capable of saltatory conduction. D) Group B fibers are highly myelinated and have the highest conduction velocities.

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

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

C) ependymal cells

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

C) generator potential

Which of the choices below describes the ANS? A) sensory neurons that convey information from somatic receptors in the head, body wall, and limbs and from receptors from the special senses of vision, hearing, taste, and smell to the CNS B) motor fibers that conduct nerve impulses from the CNS to skeletal muscles C)motor fibers that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle, and glands D) sensory and motor neurons that supply the digestive tract

C) motor fibers that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle, and glands

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

C) oligodendrocytes

An impulse from one nerve cell is communicated to another nerve cell via the ________. A) effector B) cell body C) synapse D) receptor

C) synapse

32) 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

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

C) the membrane potential has been reestablished

Which ion channel opens in response to a change in membrane potential and participates in the generation and conduction of action potentials? A) ligand-gated channel B) leakage channel C) voltage-gated channel D) mechanically gated channel

C) voltage-gated channel

Select the correct statement about serial processing. 3) A) Memories are triggered by serial processing. B) Input travels along several different pathways. C) Smells are processed by serial pathways. D) Spinal reflexes are an example of serial processing.

D) Spiral reflexes are an example of serial processing.

Which of the following is not a special characteristic of neurons? A) They conduct impulses. B) They have extreme longevity. C) They have an exceptionally high metabolic rate. D) They are mitotic.

D) They are mitotic.

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) glial cell D) association neuron

D) association neuron

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

D) the myelin sheath

Multiple sclerosis (MS) is a disease in which the myelin sheaths are destroyed. What process does this interfere with and what would be the consequence?

Demyelination interferes with saltatory conduction, which would result in a slowing down of nerve impulse propagation.

Involved in activating fibers of a skeletal muscle such as the biceps muscle.

Diverging circuit

Natural opiates that inhibit pain; effect mimicked by morphine.

Endorphins

A patient is admitted to the hospital with exacerbation of multiple sclerosis (MS). She asks the nurse,"Why did this have to happen to me again? I was doing so well." Explain why some forms of MS are characterized by periods of remission and exacerbation.

Even though someone is diagnosed with MS, the axons are not damaged. Growing numbers of sodium channels appear spontaneously in the demyelinated fibers so that conduction resumes, even if slower. This may account for the cycles of relapse and remission in different patients.

) The nodes of Ranvier are found only on myelinated, peripheral neuron processes

F

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

F

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

F

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

Graded

Why does a hyperpolarization phase generally follow a repolarization phase in an action potential?

Immediately after an action potential the potassium gates, being slow gates that do not respond to change in the electrical charge, allow additional K+ ions to flood into the cell. These K+ ions decrease the positive ion concentration momentarily below the normal -70mV and thus hyperpolarize the cell.

What is the role of microglial cells and why are they so important in the CNS?

In the presence of invading microbes, microglial cells become macrophages to phagocytize the microbes and neuronal debris. This protective role is important because cells of the immune system are denied access to the CNS.

Define neurotransmitter. Name two amino acid neurotransmitters, two catecholamines, and two peptides.

Neurotransmitters are chemical signals used as a means of communication. GABA and glycine are amino acid neurotransmitters; dopamine and norepinephrine are catecholamines; and endorphin and enkephalin are peptide transmitters.

May be involved in complex, exacting types of mental processing

Parallel after-discharge circuit

Plasma membrane exhibits chemically gated ion channels

Receptive region

Receives stimuli.

Receptive region

The specific period during which potassium ions diffuse out of the neuron due to a change in membrane permeability.

Repolarization

Axon terminals release neurotransmitters.

Secretory zone

What are the basic divisions of the peripheral nervous system?

Sensory and motor divisions. Motor has two divisions: the somatic and autonomic. The autonomic has two divisions: the sympathetic and parasympathetic.

How can a single axon respond to several different kinds of events?

Some axon terminals contain more than one kind of neurotransmitter. Therefore, the axon can release one or more neurotransmitters simultaneously, creating singular or multiple events.

Stimulation of a postsynaptic neuron by many terminals at the same time.

Spatial summation

Mediates pain.

Substance P

An insufficient stimulus.

Subthreshold stimulus

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

T

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

T

Cell bodies of sensory neurons may be located in ganglia lying outside the central nervous system. 8

T

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

T

Efferent nerve fibers may be described as motor nerve fibers.

T

Enkephalins and endorphins are peptides that act like morphine.

T

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

T

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

T

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

T

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

T

Neurons in the CNS are organized into functional groups.

T

The oligodendrocytes can myelinate several axons.

T

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

T

Because all action potentials are alike, how does the brain separate situations that require immediate attention from ordinary "positional" reports?

The importance of a stimulus is derived from the number of stimuli received from the same source. The frequency of impulse transmission indicates the stimulus intensity and the brain responds appropriately.

Any stimulus below this intensity will result in no response in a neuron.

Threshold stimulus

What symptoms would a nurse focus on in his or her care of a patient with multiple sclerosis?

Visual disturbances, paralysis, and weakness

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

c) are crucial for the development of neural connection.

The part of a neuron that conducts impulses away from its cell body is called a(n) ________. 8) A) dendrite B) Schwann cell C) axon D) neurolemma

c) axon

Which of the following is not a chemical class of neurotransmitters? 10) A) biogenic amine B) ATP and other purines C) nucleic acid D) acetycholine E) amino acid

c) nucleic acid

Which of the following is true about the movement of ions across excitable living membranes? 5) A) The bulk of the solutions inside a cell are negatively charged. B) Sodium gates in the membrane can open in response to electrical potential changes. C) Ions always move actively across membranes through leakage channels. D) Some ions are prevented from moving down their concentration gradients by ATP-driven pumps

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

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 skeletal muscle D) innervation of glands

innervation of skeletal muscle

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

neurotransmitter

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

parallel

Which pattern of neural processing is important for higher level mental processing such as problem solving?

parallel processing