Chapter 6: The Developing Brain

Question 1

cell division is also called

Answer 1

proliferation

Question 2

migration

Answer 2

neurons move to their final destinations

Question 3

three layers that emerge in embryonic development

Answer 3

ectoderm, mesoderm, and endoderm

Question 4

ectoderm cells become

Answer 4

nerve tissue

Question 5

process of ectoderm cells becoming nerve tissue is called

Answer 5

neural induction

Question 6

cells divide into

Answer 6

two identical daughter cells

Question 7

what happens after daughter cells keep splitting?

Answer 7

some go on to keep proliferating and the other may go on to its final stage

Question 8

cause of microcephaly

Answer 8

protein defects cause symmetric division to become asymmetric division

Question 9

microcephaly

Answer 9

smaller than normal head in newborns

Question 10

excessive proliferation causes

Answer 10

megalencephaly

Question 11

megalencephaly

Answer 11

baby with larger than normal head

Question 12

what begins to thicken after conception

Answer 12

ectoderm

Question 13

the three bulges that form will become the baby’s

Answer 13

hindbrain, midbrain, and forebrain

Question 14

where do neurons travel when they are produced

Answer 14

from the inner surface of neural tube to the outer surface

Question 15

radial migration

Answer 15

when the neurons that arrive the earliest form the innermost layer of the cortex and the neurons that arrive the latest form the outermost layer of the cortex

Question 16

axons

Answer 16

produce and transmit signals

Question 17

dendrites

Answer 17

receive signals

Question 18

axons do what

Answer 18

they span distances many times the size of their cell body

Question 19

longest human axons are in the

Answer 19

periphery

Question 20

a developing axon grows by the

Answer 20

extension of its growth cone

Question 21

growth cone

Answer 21

enlargement at the tip of the axon

Question 22

netrins were first found in

Answer 22

worms

Question 23

synapse

Answer 23

signaling portin of the axon

Question 24

chemical messengers

Answer 24

neurotransmitters

Question 25

how many synapses do humans have

Answer 25

trillions

Question 26

what third important player in formation of a synapse has been identified

Answer 26

astrocytes

Question 27

motor neuron neurotransmitter

Answer 27

acetylcholine

Question 28

when neurons are maintained in a culture dish they produce

Answer 28

norepinephrine

Question 29

cultured with other neurons they form

Answer 29

acetylcholine

Question 30

myelination

Answer 30

the fatty wrapping of axons by extensions of glia

Question 31

spaced gaps interrupting the sheath

Answer 31

nodes of Ranvier

Question 32

alternating pattern of insulation and nodes is called

Answer 32

saltatory conduction

Question 33

saltatory

Answer 33

leaping

Question 34

apoptosis

Answer 34

process of programmed cell death initiated in the cells

Question 35

life-sustaining chemical signals are called

Answer 35

trophic factors

Question 36

nerve growth factor is important for the survival of

Answer 36

sensory neurons

Question 37

astrocytes also help to

Answer 37

form eye-specific connections