What are the functional units of the nervous system?

Question 1

glial cell

Answer 1

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

Question 1

mutation

Answer 1

Alteration of an allele that yields a different version of the allele.

Question 2

cell body (soma)

Answer 2

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

Question 2

Huntington’s disease

Answer 2

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

Question 3

pyramidal cell

Answer 3

Distinctive interneuron found in the cerebral cortex.

Question 3

transgenic animal

Answer 3

Product of technology in which number of genes or a single gene from one species is introduced into the genome of another species and passed along and expressed in subsequent generations.

Question 4

homozygous

Answer 4

Having two identical alleles for a trait.

Question 4

multiple sclerosis (MS)

Answer 4

Nervous-system disorder that results from the loss of myelin (glial-cell covering) around neurons.

Question 6

allele

Answer 6

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

Question 7

Schwann cell

Answer 7

Glial cell in the peripheral nervous system that myelinates sensory and motor axons.

Question 9

bipolar neuron

Answer 9

Sensory neuron with one axon and one dendrite.

Question 10

terminal button (end foot)

Answer 10

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

Question 11

astrocyte

Answer 11

Star-shaped glial cell that provides structural support to neurons in the central nervous system and transports substances between neurons and blood vessels.

Question 11

pump

Answer 11

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

Question 12

wild type

Answer 12

Refers to a normal (most common in a population).

Question 13

gate

Answer 13

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

Question 14

blood-brain barrier

Answer 14

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 15

axon hillock

Answer 15

Juncture of soma and axon where the action potential begins.

Question 15

channel

Answer 15

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

Question 16

synapse

Answer 16

Junction between one neuron and another that forms the information-transfer site between neurons.

Question 17

protein

Answer 17

Folded-up polypeptide chain.

Question 17

sensory neuron

Answer 17

Neuron that carries incoming information from sensory receptors into the spinal cord and brain.

Question 19

axon

Answer 19

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

Question 20

hydrocephalus

Answer 20

Buildup of pressure in the brain and, in infants, swelling of the head caused if the flow of cerebrospinal fluid is blocked; can result in retardation.

Question 22

heterozygous

Answer 22

Having two different alleles for the same trait.

Question 23

interneuron

Answer 23

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

Question 24

tumor

Answer 24

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

Question 25

Purkinje cell

Answer 25

Distinctive interneuron found in the cerebellum.

Question 26

Tay-Sachs disease

Answer 26

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 retardation, physical changes, and death by about age 5.

Question 28

dendrite

Answer 28

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

Question 30

ependymal cell

Answer 30

Glial cell that makes and secretes cerebrospinal fluid; found on the walls of the ventricles in the brain.

Question 31

myelin

Answer 31

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

Question 32

somatosensory neuron

Answer 32

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

Question 34

microglia

Answer 34

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

Question 35

oligodendroglia

Answer 35

Glial cells in the central nervous system that myelinate axons.

Question 36

Down syndrome

Answer 36

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

Question 37

dendritic spine

Answer 37

Protrusion from a dendrite that greatly increases the dendrite’s surface area and is the usual point of dendritic contact with the axons of other cells.

Question 38

axon collateral

Answer 38

Branch of an axon

Question 39

paralysis

Answer 39

Loss of sensation and movement due to nervous-system injury.

Question 40

motor neuron

Answer 40

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

Question 41

gene

Answer 41

DNA segment that encodes the synthesis of a particular protein.