Lecture Exam 3 Review Ch 12

Question 1

central nervous system

Answer 1

brain and spinal cord

Question 2

peripheral nervous system

Answer 2

nerves and sensory receptors

Question 3

nerve

Answer 3

a bundle of hundreds to thousands of axons plus associated connective tissue and blood vessels that lies outside the brain and spinal cord

Question 4

cranial nerves

Answer 4

12 pairs; emerge from the brain

Question 5

spinal nerves

Answer 5

31 pairs; emerge from the spinal cord

Question 6

sensory receptor

Answer 6

a structure of the nervous system that monitors changes in the external or internal environment

Question 7

sensory/afferent division of the PNS

Answer 7

conveys input into the CNS from sensory receptors in the body; provides the CNS with sensory information about the somatic senses (tactile, thermal, pain, and proprioceptive sensations) and special senses (smell, taste, vision, hearing, and equilibrium)

Question 8

motor/efferent division of the PNS

Answer 8

conveys output from the CNS to effectors (muscles and glands); further divided into the somatic and autonomic nervous systems

Question 9

somatic nervous system

Answer 9

conveys output from the CNS to skeletal muscles only; voluntary

Question 10

autonomic nervous system

Answer 10

conveys output from the CNS to smooth muscle, cardiac muscle, and glands; involuntary; sympathetic and parasympathetic divisions

Question 11

enteric plexus

Answer 11

branch of the ANS; extensive network of over 100 million neurons confined to the wall of the digestive canal; helps regulate the activity of the smooth muscle and glands of the digestive canal; can function independently but communicate with and are regulated by the other branches of the ANS

Question 12

functions of the nervous system

Answer 12

sensory function, integrative function, motor function

Question 13

sensory function

Answer 13

sensory receptors detect internal stimuli, such as an increase in blood pressure, or external stimuli, such as a raindrop landing on your arm; this sensory information is then carried into the brain and spinal cord through cranial and spinal nerves

Question 14

integrative function

Answer 14

the nervous system processes sensory information by analyzing it and making decisions for appropriate responses- an activity known as integration

Question 15

motor function

Answer 15

once sensory information is integrated, the nervous system may elicit an appropriate motor response by activating effectors through cranial and spinal nerves; stimulation of the effectors causes muscles to contract and glands to secrete

Question 16

stimulus

Answer 16

any change in the environment that is strong enough to initiate a nerve impulse

Question 17

nerve impulse/action potential

Answer 17

an electrical signals that propagates along the surface of the membrane of a neuron

Question 18

neuronal cell body

Answer 18

perikaryon/soma; contains a nucleus surrounded by cytoplasm that includes typical cellular organelles and free ribosomes and prominent clusters of rough ER

Question 19

Nissl bodies

Answer 19

prominent clusters of rough ER

Question 20

neurofibrils

Answer 20

bundles of intermediate filaments that provide the cell shape and support

Question 21

microtubules

Answer 21

assist in moving materials between the cell body and axon

Question 22

lipofuscin

Answer 22

a pigment in aging neurons that occurs as clumps of yellowish-brown granules in the cytoplasm

Question 23

somatic spines

Answer 23

small projections of the plasma membrane that are receptor sites that band chemical messengers from other neurons

Question 24

ganglion

Answer 24

collection of neuron cell bodies outside the CNS

Question 25

nerve fiber

Answer 25

general term for any neuronal process that emerges from the cell body of a neuron

Question 26

dendrites

Answer 26

receiving or input portions of a neuron

Question 27

dendritic spines

Answer 27

receptor sites for binding chemical messengers from other neurons

Question 28

axon

Answer 28

propagates nerve impulses toward another neuron, a muscle fiber, or a gland cell

Question 29

axon hillock

Answer 29

cone-shaped elevation of the cell body that joins the axon

Question 30

initial segment/trigger zone

Answer 30

part of the axon closest to the axon hillock where the nerve impulses arise

Question 31

axoplasm

Answer 31

cytoplasm of an axon

Question 32

axolemma

Answer 32

plasma membrane of an axon

Question 33

axon collaterals

Answer 33

side branches of axon

Question 34

axon terminals

Answer 34

axon and its collaterals end by dividing into many fine processes

Question 35

synapse

Answer 35

site of communication between two neurons or between a neuron and an effector cell

Question 36

synaptic end bulbs

Answer 36

the tips of some axon terminals that swell into bulb shaped structures

Question 37

varicosites

Answer 37

another string of swollen bumps that may be at the tips of axon terminals

Question 38

synaptic vesicles

Answer 38

membrane-enclosed sacs that store neurotransmitters

Question 39

neurotransmitter

Answer 39

a molecule released from a synaptic vesicle that excites or inhibits another neuron, muscle fiber, or gland cell

Question 40

multipolar neurons

Answer 40

several dendrites and one axon

Question 41

bipolar neurons

Answer 41

one main dendrite and one axon

Question 42

unipolar

Answer 42

dendrites and one axon that are fused together to form a continuous process that emerges from the cell body

Question 43

sensory neurons

Answer 43

either contain sensory receptors at their distal ends or are located just after sensory receptors that are separate cells; once an appropriate stimulus activates a sensory receptor, the sensory neuron forms a nerve impulse in its axon and the nerve impulse is conveyed into the CNS through cranial or spinal nerves

Question 44

motor neurons

Answer 44

convey nerve impulses away from the CNS to effectors in the PNS through cranial or spinal nerves

Question 45

interneurons

Answer 45

mainly located within the CNS between sensory and motor neurons; integrate incoming sensory information from sensory neurons and then elicit a motor response by activating the appropriate motor neurons

Question 46

astrocytes

Answer 46

star shaped cells with many processes that form the blood-brain barrier and maintain the neuronal chemical environment

Question 47

oligodendrocytes

Answer 47

form and maintain the myelin sheath in the CNS

Question 48

myelin sheath

Answer 48

multilayered lipid and protein covering around some axons that insulates them and increases the speed of nerve impulse conduction

Question 49

microglial cells

Answer 49

function as phagocytes

Question 50

ependymal cells

Answer 50

cuboidal to columnar cells arranged in a single layer that possess microvilli and cilia; line the ventricles of the brain and central canal of the spinal cord and produce and circulate CSF

Question 51

Schwann cells

Answer 51

form myelin sheath in the PNS

Question 52

satellite cells

Answer 52

regulate the exchanges of materials between neuronal cell bodies and interstitial fluid

Question 53

neurolemma

Answer 53

outer nucleated cytoplasmic layer of the Schwann cell that encloses the myelin sheath

Question 54

myelin sheath gaps

Answer 54

node of Ranvier

Question 55

nucleus

Answer 55

cluster of neuronal cell bodies located in the CNS

Question 56

tract

Answer 56

bundle of axons that is located in the CNS

Question 57

white matter

Answer 57

composed primarily of myelinated axons

Question 58

gray matter

Answer 58

contains neuronal cell bodies, dendrites, unmyelinated axons, axon terminals, and neuroglia

Question 59

graded potentials

Answer 59

short distance communication only; a small deviation from the resting membrane potential that makes the membrane either more polarized (inside more negative) or less polarized (inside less negative)

Question 60

action potentials

Answer 60

allow communication over long distances; a sequence of rapidly occurring events that decrease and reverse the membrane potential and then eventually restore it to the resting state

Question 61

membrane potential

Answer 61

an electrical potential difference (voltage) across the membrane

Question 62

resting membrane potential

Answer 62

membrane potential in excitable cells

Question 63

leak channels

Answer 63

gates randomly alternate between open and closed positions

Question 64

ligand-gated channels

Answer 64

open and close in response to the binding of a ligand/chemical stimulus

Question 65

mechanically gated channels

Answer 65

open or close in response to mechanical stimulation in the form of vibration, touch, pressure, or tissue stretching

Question 66

voltage-gated channels

Answer 66

open in response to a change in membrane potential

Question 67

hyperpolarizing graded potential

Answer 67

response makes the membrane more polarized (inside more negative)

Question 68

depolarizing graded potential

Answer 68

response makes the membrane less polarized (inside less negative)

Question 69

threshold