Chapter 3

Question 1

cell body (soma)

Answer 1

Core region of the cell containing the nucleus and other organelles for making proteins.

Question 2

dendrite

Answer 2

Branching extension of a neuron’s cell membrane; greatly increases the cell’s surface area; collects information from other cells.

Question 3

axon

Answer 3

Root, or single fiber, of a neuron that carries messages to other neurons.

Question 4

neural network

Answer 4

Functional group of neurons that connects wide areas of the brain and spinal cord.

Question 5

connectome

Answer 5

Comprehensive map of all structural connectivity (the physical wiring) in an organism’s nervous system.

Question 6

dendritic spine

Answer 6

Protrusion that greatly increases the dendrite’s surface area; typical point of dendritic contact with the axons of other cells.

Question 7

axon hillock

Answer 7

Juncture of soma and axon.

Question 8

axon collateral

Answer 8

Branch of an axon.

Question 9

terminal button (end foot)

Answer 9

Knob at the tip of an axon that conveys information to other neurons.

Question 10

synapse

Answer 10

Spatial junction between one neuron and another; forms the information transfer site between neurons.

Question 11

sensory neuron

Answer 11

Cell that detects or carries sensory information into the spinal cord and brain.

Question 12

interneuron

Answer 12

Association cell interposed between a sensory neuron and a motor neuron; in mammals, interneurons constitute most of the brain’s neurons.

Question 13

motor neuron

Answer 13

Cell that carries efferent information from the brain and spinal cord to make muscles contract.

Question 14

bipolar neuron

Answer 14

Sensory neuron with one axon and one dendrite.

Question 15

somatosensory neuron

Answer 15

Brain cell that brings sensory information from the body into the spinal cord.

Question 16

pyramidal cell

Answer 16

Distinctively shaped interneuron found in the cerebral cortex.

Question 17

Purkinje cell

Answer 17

Distinctively shaped interneuron found in the cerebellum.

Question 18

glial cell

Answer 18

Nervous system cell that provides insulation, nutrients, and support and that aids in repairing neurons and eliminating waste products.

Question 19

ependymal cell

Answer 19

Glial cell that makes and secretes CSF; found on the walls of the brain’s ventricles.

Question 20

hydrocephalus

Answer 20

Buildup of fluid pressure in the brain and, in infants, swelling of the head, if the flow of CSF is blocked; can result in intellectual impairment.

Question 21

tumor

Answer 21

Mass of new tissue that grows uncontrolled and independent of surrounding structures.

Question 22

astrocyte

Answer 22

Star-shaped glial cell that provides structural support to CNS neurons and transports substances between neurons and blood vessels.

Question 23

blood–brain barrier

Answer 23

Tight junctions between the cells that compose blood vessels in the brain, providing a barrier to the entry of an array of substances, including toxins, into the brain.

Question 24

microglia

Answer 24

Glial cells that originate in the blood, aid in cell repair, and scavenge debris in the nervous system.

Question 25

myelin

Answer 25

Glial coating that surrounds axons in the central and peripheral nervous systems; prevents adjacent neurons from short-circuiting.

Question 26

oligodendroglia

Answer 26

Glial cells in the CNS that myelinate axons.

Question 27

Schwann cell

Answer 27

Glial cell in the PNS that myelinates sensory and motor axons.

Question 28

paralysis

Answer 28

Loss of sensation and movement due to nervous system injury.

Question 29

gene

Answer 29

DNA segment that encodes the synthesis of a particular protein.

Question 30

protein

Answer 30

Folded-up polypeptide chain that serves a particular function in the body.

Question 31

channel

Answer 31

Opening in a protein embedded in the cell membrane that allows the passage of ions.

Question 32

gate

Answer 32

Protein embedded in a cell membrane that allows substances to pass through the membrane on some occasions but not on others.

Question 33

pump

Answer 33

Protein in the cell membrane that actively transports a substance across the membrane.

Question 34

allele

Answer 34

Alternative form of a gene; a gene pair contains two alleles.

Question 35

homozygous

Answer 35

Having two identical alleles for a trait.

Question 36

heterozygous

Answer 36

Having two different alleles for the same trait.

Question 37

mutation

Answer 37

Alteration of an allele that yields a different version of its protein.

Question 38

Tay-Sachs disease

Answer 38

Inherited birth defect caused by the loss of genes that encode the enzyme necessary for breaking down certain fatty substances; appears 4 to 6 months after birth and results in intellectual disability, physical changes, and death by about age 5.

Question 39

wild type

Answer 39

Typical allele (most common in a population).

Question 40

Huntington disease

Answer 40

Hereditary disease characterized by chorea (ceaseless involuntary jerky movements) and progressive dementia, ending in death.

Question 41

Down syndrome

Answer 41

Chromosomal abnormality resulting in intellecutal impairment and other abnormalities, usually caused by an extra chromosome 21.

Question 42

transgenic animal

Answer 42

Product of technology in which one or more genes from one species is introduced into the genome of another species to be passed along and expressed in subsequent generations.

Question 43

gene (DNA) methylation

Answer 43

Epigenetic process in which a methyl group attaches to the DNA sequence, suppressing or enabling gene expression.