Chapter 11 Review

If a postsynaptic neuron is stimulated to threshold by spatial summation this implies that ________.

the postsynaptic cell has many synapses with many presynaptic neurons

The peripheral nervous system is divided into afferent and efferent divisions.

True

Reflexes are rapid, automatic responses to stimuli that will produce the same effect every time.

True

Which of the following is false or incorrect?

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

An action potential is regarded as an example of a positive feedback. Which of the following examples below best illustrates the positive feedback aspect of an action potential?

A threshold stimulus will cause the opening of voltage gated sodium ion channels that will cause further depolarizing stimulus. This stimulus will open still more voltage gated sodium ion channels.

Match the following: A) Receptive region B) Secretory region C) Conducting region D) Trigger zone E) Secretory zone

Area where nerve impulse is generated = D Receives stimuli = A Plasma membrane exhibits voltage-gated Na+ and K+ channels = C Plasma membrane exhibits voltage-gated Ca2+ channels. = B Axon terminals release neurotransmitters. = E Plasma membrane exhibits chemically gated ion channels. = A

Match the following: A) Threshold stimulus B) Depolarization C) Hyperpolarization D) Repolarization

B D C A

When a neurotransmitter like acetylcholine is acting in an excitatory manner which of the following is likely a result of the acetylcholine acting on the postsynaptic cell?

Chemically gated sodium channels will open.

The effect of acetylcholine can be stimulating or inhibiting. Which of the following gives the best explanation for why this is so?

Different postsynaptic cells will have different receptors.

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

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

Using Figure 11.2, match the following:

Ion channel = E Synaptic vesicles. = C Calcium ions. = A Postsynaptic membrane. = B Synaptic cleft. = D

Match the following: A) Converging circuit B) Diverging circuit C) Parallel after-discharge circuit D) Reverberating circuit

One incoming axon triggers responses in ever-increasing numbers farther and farther along the circuit = B May be involved in complex, exacting types of mental processing = C Involved in control of rhythmic activities such as breathing = D Involved in activating fibers of a skeletal muscle such as the biceps muscle. = B Different types of sensory input can have the same ultimate effect. = A

Some nerve fibers of the peripheral nervous system have the ability to regenerate after damage has occurred. Which of the following cells is most responsible for aiding in this regulation?

Schwann cells

Which of the following is true about the movement of ions across excitable living membranes?

Sodium gates in the membrane can open in response to electrical potential changes.

Select the correct statement regarding chemical synapses.

The synaptic cleft uses the action potential to transmit a chemical signal to the postsynaptic cell.

The action potential is caused by permeability changes in the plasma membrane.

True

Which of the following is NOT a characteristic of neurons?

They are mitotic.

The depolarization phase of an action potential is punctuated by the closing of inactivation gates in the voltage gated sodium ion channels. All of the following are consequences of this inactivation except one. Choose the statement below that is not a consequence of the closing of inactivating gates.

This allows for the efflux (diffusion out) of potassium ions, resulting in the repolarization of the cell.

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

True

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.

True

Axon diameter and degree of myelination determine nerve impulse conduction velocity.

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

Enkephalins and endorphins are peptides that act like morphine.

True

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

True

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

True

Which of the following describes the nervous system integrative function?

analyzes sensory information, stores information, makes decisions

Using Figure 11.1, match the following:

Which neuron would activate a muscle? = A Which neuron would be found in the retina of the eye? = B Which neuron is a sensory neuron found in a reflex arc? = C Which neuron is never myelinated? = B Which neuron is typically involved in the special senses of sight and smell? = B In a reflex arc, which neuron has its cell body inside the spinal cord? = A Which neuron is common only in the dorsal root ganglia of the spinal cord and sensory ganglia of cranial nerves? = C Which is by far the most common neuron type? = A

If a postsynaptic cell is stimulated to threshold by temporal summation this implies that ________.

a presynaptic neuron is sending frequent EPSP

The period after an initial stimulus when a neuron is not sensitive to another stimulus is the ________.

absolute refractory period

Which of the following is an excitatory neurotransmitter secreted by motor neurons innervating skeletal muscle?

acetylcholine

It is important for newly developed neurons to form synapses with other neurons. Which cells are most responsible for guiding the formation of these particular junctions?

astrocytes

The term central nervous system refers to the ________.

brain and spinal cord

These cells in the CNS have cilia that move in order to circulate cerebrospinal fluid.

ependymal cells

Bipolar neurons are commonly ________.

found in the retina of the eye

What does the central nervous system use to determine the strength of a stimulus?

frequency of action potentials

Collections of nerve cell bodies outside the central nervous system are called ________.

ganglia

Which of the following is NOT a function of dendrites?

generate nerve impulses and transmit them away from the cell body

When a sensory neuron is excited by some form of energy, the resulting graded potential is called a(n) ________.

generator potential

Which of the following neurotransmitters is the principal inhibitory neurotransmitter of the spinal cord?

glycine

An inhibitory postsynaptic potential (IPSP) is associated with ________.

hyperpolarization

When a neurotransmitter like GABA is acting in an inhibitory manner which of the following is likely a result of the GABA acting on the postsynaptic cell?

hyperpolarization of the postsynaptic cell membrane

Loss of function in the enzyme acetylcholine esterase would result in which of the following?

inability to destroy and remove acetylcholine from the synaptic cleft

Which of the following is NOT a function of the autonomic nervous system?

innervation of skeletal muscle

A neuron that has as its primary function the job of connecting other neurons is called a(n) ________.

interneuron

Meningitis can be caused by infection of the central nervous system by bacteria. Which cells would be most responsible for removing the infection?

microglia

Which of the choices below describes the ANS?

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

The interior surface of a neuron's plasma membrane at resting membrane potential will have a ________.

negative charge and contains less sodium than outside of the cell

Like all cells, the neurons' internal organization dictates its function. Neurons have relatively many mitochondria, an extensive network of rough endoplasmic reticulum and many clusters of ribosomes. These cellular features indicate all of the following EXCEPT ________.

neurons have stable, relatively unchanging internal environments

Which of the following is NOT a chemical class of neurotransmitters?

nucleic acid

Schwann cells are functionally similar to ________.

oligodendrocytes

Nerve impulses are sent to slow the heart's rate of contraction. The nerve fibers sending these signals will most likely belong to which division of the nervous system?

parasympathetic division

Cranial nerve II, the optic nerve sends nerve impulses to the brain carrying information about the things we see. These nerve fibers most likely belong to which division of the nervous system?

sensory (afferent) division

Nerve impulses leading to the brain carry information about cool temperatures on the skin. The nerve fibers sending these signals will most likely belong to which division of the nervous system?

sensory (afferent) division

Which of the following describes the excitatory postsynaptic potential?

short distance depolarization

Nerve impulses leading to the skeletal muscle carry information to direct movement. The nerve fibers sending these signals will most likely belong to which division of the nervous system?

somatic nervous system

If a motor neuron in the body were stimulated by an electrode placed about midpoint along the length of the axon, ________.

the impulse would spread bidirectionally

A second nerve impulse cannot be generated until ________.

the membrane potential has been reestablished

Saltatory conduction is made possible by ________.

the myelin sheath

During the relative refractory period of an action potential, a larger than normal stimulus is needed to cause another action potential. This is due to the fact that ________.

the voltage gated potassium ion channels remain open long enough to hyperpolarize the axon membrane

Which ion channel opens in response to a change in membrane potential and participates in the generation and conduction of action potentials?

voltage-gated channel

Immediately after an action potential has peaked, which of the following channels will open?

voltage-gated potassium channels