ch. 7 quiz

In saltatory conduction, nerve impulses jump from one exposed region of the axon to another. This exposed region is called the ________.

node of Ranvier

An impulse relayed along a myelinated axon "jumps" from _____ to _____.

node of Ranvier ... node of Ranvier

Which one of the following ions outside the neuron would make it very difficult for a depolarization to occur?

sodium

A stimulus has opened the voltage-gated sodium channels in an area of a neuron's plasma membrane. As a result, _____ rushes into the neuron and diffuses to adjacent areas; this in turn results in the _____ in the adjacent areas.

sodium ... opening of voltage-gated sodium channels

What part of a neuron relays signals from one neuron to another neuron or to an effector?

synaptic terminal

Repolarization __________.

is due to movement of potassium ions out of the axon

When the neurotransmitter crosses the synapse, what happens?

The neurotransmitter causes the channel to open, and this can cause a depolarization of the postsynaptic membrane.

A neuron has a resting potential of about _____ millivolts.

-70

What occurs when the action potential reaches the synaptic terminal?

Calcium ions rush into the presynaptic terminal.

The short branching projections of a neuron, which provide surface area for sending and receiving signals from other cells.

Dendrite

Synapse in which neurotransmitters allow sodium to enter the postsynaptic cell.

Excitatory synapse

Infants require many nutrients early in life, including lipids such as fats. A low-fat diet for infants is not recommended because, among other things, it can impact the development of the nervous system. Why does the developing nervous system need lipids?

Glial cells need lipids to produce the myelin sheath.

Synapse in which neurotransmitters decrease the chance of an action potential on the postsynaptic cell.

Inhibitory synapse

Association neurons that are located between the sensory and motor neurons, where they integrate or interpret the sensory signals.

Interneurons

Membrane proteins that allow specific charged molecules to pass through from one side of membrane to the other.

Ion channels

Which statement accurately describes the myelin sheath?

It speeds up the conduction of nervous impulses.

Multiple sclerosis is a disease in which the myelin sheath is destroyed. What will happen to nerve conduction speed in affected neurons?

It will slow down dramatically.

Specific neurons that carry information away from the brain and spinal cord to an effector such as a muscle or a gland.

Motor neuron

What does saltatory conduction mean?

Saltatory conduction means that the nerve impulse seems to jump from one node to the next—and is regenerated as it speeds along.

What type of cell makes up the myelin sheath of a motor neuron?

Schwann cells

When speaking of myelinating glial cells, we can correctly say that ________.

Schwann cells are glial cells found outside the brain and spinal cord; oligodendrocytes are glial cells found in the brain and spinal cord

A specific type of neuron that conducts information toward the brain and spinal cord from a sensory receptor

Sensory neuron

Part of the neuron where neurotransmitters are released.

Synaptic knobs

A new drug interferes with the function of the dendrites of a neuron. What will happen to this neuron?

The neuron cannot be stimulated to send a signal along its axon.

Which of these statements best describes a synapse?

The synapse includes the space between the presynaptic membrane and the postsynaptic membrane.

Which of the following is NOT a method for clearing neurotransmitters from a synapse?

They can be taken up into the postsynaptic neuron.

Sodium and potassium ions cross the neuron's membrane to cause which of the following processes?

action potential

A nerve impulse does not vary in intensity with regard to the strength of the stimulus. This is known as what principle?

all-or-nothing principle

A single, long extension of a neuron's cell body that functions to transmit an incoming message or impulse.

axon

An action potential moves along a(n) _____.

axon

The part of the nerve cell responsible for origination of the nerve impulse is the ________.

axon hillock, because this is the specific area of the nerve cell that generates the electrical impulse that travels along the axon

Name the three principal parts of the nerve cell.

axon, dendrites, cell body

A nerve impulse moves away from a neuron's cell body along _____.

axons

Which of the following is a chemical signal that diffuses across the gap between adjacent neurons to convey a message to the next cell?

neurotransmitter

A neuron's nucleus is located in its _____.

cell body

An action potential would most commonly arrive from which of the following structures before arriving at the axon?

cell body

A nerve impulse moves toward a neuron's cell body along _____.

dendrites

Neurons with a myelin sheath carry impulses __________ unmyelinated cells.

faster than

Which of the following parts of the nervous system is closest to a muscle?

motor neuron

Which of these diseases involves the destruction of the myelin sheath on certain neurons within the brain and spinal cord?

multiple sclerosis

You might have been accidentally exposed to an insecticide while working in a citrus grove. What symptoms of poisoning would you watch for?

muscle tremors

Axons insulated by a(n) _____ are able to conduct impulses faster that those not so insulated.

myelin sheath

The transmission of a nerve impulse first triggers the _____.

opening of voltage-gated sodium channels and the diffusion of sodium ions into the neuron

Which of the following is the correct sequence for the electrical transmission of a nerve impulse?

presynaptic neuron, synapse, postsynaptic neuron

A neuron's membrane that maintains a charge difference across its surface in which the inside is more negative than the outside is called ________.

resting potential

The specialized membrane proteins that actively transport sodium and potassium ions across the plasma membrane are known as the ________.

sodium-potassium pump

The combined effects of inhibitory and excitatory effects on a postsynaptic cell will decide whether that cell generates an action potential. This principle is called ________.

summation

The junction between a neuron and another cell.

synapse

At rest, which of these plays a role in establishing the charge differential across a neuron's plasma membrane?

the sodium-potassium pump moving sodium ions out of the neuron and potassium ions into the neuron