Chapter 35

Question 1

A network of many interconnected nerve cells.

Answer 1

nervous system

Question 2

Nerve cell; the basic fundamental unit of nervous systems.

Answer 2

neuron

Question 3

A neuron that receives and transmits information about an animal’s environment or its internal physiological state.

Answer 3

sensory neurons

Question 4

A neuron that processes information received by sensory neurons and transmits it to motor neurons in different body regions.

Answer 4

interneuron

Question 5

A neuron that, on receiving information from interneurons, effects a response in the body.

Answer 5

motor neuron

Question 6

The active regulation and maintenance, in animals, organs, or cells, of a stable internal physiological state in the face of a changing external environment.

Answer 6

homeostasis

Question 7

A group of nerve cell bodies that processes sensory information received from a local, nearby region, resulting in a signal to motor neurons that control some physiological function of the animal.

Answer 7

ganglion

Question 8

The centralized concentration of neurons in an organ that processes complex sensory stimuli from the environment or from anywhere in the body.

Answer 8

brain

Question 9

A bundle of long fiberlike extensions from multiple nerve cells that serves as the central nervous system of invertebrates such as flatworms and earthworms.

Answer 9

nerve cord

Question 10

A bundle of long fiberlike extensions from multiple nerve cells.

Answer 10

nerves

Question 11

The concentration of nervous system components at one end of the body.

Answer 11

cephalization

Question 12

A fiberlike extension from the cell body of a neuron that receives signals from other nerve cells or from specialized sensory endings; the input end of a nerve cell.

Answer 12

dendrite

Question 13

The fiberlike extension from the cell body of a neuron that transmits signals away from the nerve’s cell body; the output end of a nerve cell.

Answer 13

axon

Question 14

The junction of the nerve cell body and its axon.

Answer 14

axon hillock

Question 15

A brief electrical signal transmitted from the nerve cell body along one or more axon branches.

Answer 15

action potential

Question 16

A junction through which the axon terminal communicates with a neighboring cell.

Answer 16

synapse

Question 17

The space between the axon of the presynaptic cell and the neighboring postsynaptic cell.

Answer 17

synaptic cleft

Question 18

A molecule that conveys a signal from the end of the axon to the postsynaptic target cell.

Answer 18

neurotransmitter

Question 19

A type of cell that surrounds neurons and provides them with nutrition and physical support.

Answer 19

glial cell

Question 20

A type of star-shaped glial cell that contributes to the blood–brain barrier by surrounding blood vessels in the brain and thus limiting the size of compounds that can diffuse from the blood into the brain.

Answer 20

astrocyte

Question 21

A difference in electrical charge across the plasma membrane.

Answer 21

membrane potential

Question 22

Having opposite properties in opposite parts; describes a resting membrane potential in which there is a buildup of negatively charged ions on the inside surface of the cell’s plasma membrane and positively charged ions on its outer surface.

Answer 22

polarized

Question 23

The negative voltage across the membrane at rest.

Answer 23

resting membrane potential

Question 24

An increase in membrane potential

Answer 24

depolarization

Question 25

Ion membrane channels that open and close in response to changes in membrane potential.

Answer 25

voltage-gated channels

Question 26

The critical depolarization voltage of –50 mV required for an action potential.

Answer 26

threshold potential

Question 27

In the nervous system, the type of feedback in which a stimulus causes a response that leads to an enhancement of the original stimulus that leads to a larger response. In the endocrine system, the type of feedback in which a stimulus causes a response, and that response causes a further response in the same direction. In both cases, the process reinforces itself until interrupted.

Answer 27

postive feedback

Question 28

The period following an action potential during which the inner membrane voltage falls below and then returns to the resting potential.

Answer 28

refractory period

Question 29

Continuing without input from an outside source; action potentials are self-propagating in that they move along axons by sequentially opening and closing adjacent ion channels.

Answer 29

self-propagating

Question 30

Lipid-rich layers or sheaths formed by glial cells that wrap around the axons of vertebrate neurons and provide electrical insulation.

Answer 30

myelin

Question 31

Sites on an axon that lie between adjacent myelin-wrapped segments, where the axon membrane is exposed.

Answer 31

nodes of Ranvier

Question 32

The movement of an action potential along a myelinated axon, “jumping” from node to node.

Answer 32

saltatory propagation

Question 33

A receptor that alters the flow of ions across the plasma membrane when bound by its ligand.

Answer 33

ligand-gated ion channel

Question 34

A positive change in the postsynaptic membrane potential.

Answer 34

excitatory postsynaptic potential (EPSP)

Question 35

A negative change in the postsynaptic membrane potential.

Answer 35

inhibitory postsynaptic potential (IPSP)

Question 36

The frequency of synaptic stimuli; the integration of sensory stimuli that are received repeatedly over time by the same sensory cell.

Answer 36

temporal summation

Question 37

The converging of multiple receptors onto a neighboring neuron, increasing its firing rate proportionally to the number of signals received.

Answer 37

spatial summation

Question 38

Collectively, the sensory and motor nerves, including the cranial and spinal nerves, and interneurons and ganglia.

Answer 38

peripheral nervous system (PNS)

Question 39

In vertebrates, the brain and spinal cord; in invertebrates, centralized information-processing ganglia.

Answer 39

central nervous system (CNS)

Question 40

In vertebrates, a central tract of neurons that passes through the vertebrae to transmit information between the brain and the periphery of the body.

Answer 40

spinal cord

Question 41

In vertebrates, a nerve that links specialized sensory organs to the brain; most contain axons of both sensory and motor neurons.

Answer 41

cranial nerve

Question 42

In vertebrates, a nerve running from the spinal cord to the periphery containing axons of both sensory and motor neurons.

Answer 42

spinal nerve

Question 43

Describes the component of the nervous system that handles sensing and responding to external stimuli.

Answer 43

voluntary

Question 44

Describes the component of the nervous system that regulates internal bodily functions.

Answer 44

involuntary

Question 45

The voluntary component of the peripheral nervous system, which is made up of sensory neurons that respond to external stimuli and motor neurons that synapse with voluntary muscles.

Answer 45

somatic nervous system

Question 46

The involuntary component of the peripheral nervous system, which controls internal functions of the body such as heart rate, blood flow, digestion, excretion, and temperature.

Answer 46

autonomic nervous system

Question 47

The division of the autonomic nervous system that generally produces arousal and increased activity; active in the fight-or-flight response.

Answer 47

sympathetic division

Question 48

The division of the autonomic nervous system that slows the heart and stimulates digestion and metabolic processes that store energy, enabling the body to “rest and digest.”

Answer 48

parasympathetic division

Question 49

Describes the effect in which the final product of a biochemical pathway inhibits the first step; the process in which a stimulus acts on a sensor that communicates with an effector, producing a response that opposes the initial stimulus. Negative feedback is used to maintain steady conditions, or homeostasis.

Answer 49

negative feedback

Question 50

A reflex commonly tested by physicians to evaluate peripheral nervous and muscular system function.

Answer 50

knee-jerk extension reflex