Development of the Brain

Question 1

define zygote

Answer 1

fertilized egg

Question 2

define embryo

Answer 2

fetus after week 10

Question 3

define fetus

Answer 3

unborn human baby

Question 4

define infant

Answer 4

born human baby

Question 5

explain how the nervous system originates from one of the embryo layers

Answer 5

ectoderm (outer layer) becomes nervous system. it first forms the neural plate, then separates that plate and forms a neural groove, then it rebinds and makes the neural tube. The neural tube continues to grow into brain and spinal cord.

Question 6

describe each of the six stages of neural development

Answer 6

1. neurogenesis (mitosis produces neurons from non-neuronal cells)
2. cell migration (cells move to establish distinct populations)
3. differentiation (cells become distinct neurons or glial cells)
4. synaptogenesis (establishment of synaptic connections)
5. neural cell death (selective death of some nerve cells)
6. synapse rearrangement (loss of synapses, fine tuning)

Question 7

explain what the ventricular and marginal zones are

Answer 7

ventricular-embryonic layer of tissue that differentiates cells into neurons or glial cells
marginal-differentiate neurons into different types of neurons

Question 8

explain the terms stem cell and cell maturation

Answer 8

stem cell-undifferentiated cell that can assume a new cell fate
cell maturation-cells specializing and maturing

Question 9

describe the role of the radial glial cells and where they are located, as well as the role of the cell adhesion molecules

Answer 9

acts as guides and located in the gyrus. CAMs are the system to guide the cells by pulling along the glial cells that are guiding the neurons

Question 10

describe the type of influences on cell differentiation and the role of the notochord

Answer 10

cell autonomous (independent of other cells and driven by genes) and neural environment (cells affected by influence of other cells). The notochord releases protein signals.

Question 11

describe how dendrites and axons grow and what the filopodia and lamellipodia are

Answer 11

extensions emerge from growth cones and form the tips of axons and dendrites. filopodia-finger shape, lamellipoidia- sheetlike extension

Question 12

explain what are chemorepellents and chemeoattractants

Answer 12

chemorepellents-repel growth cones (prevents axons from crossing middle line)
chemeoattractants-chem signals that attract certain growth cones

Question 13

describe the process of auto-destruction of the cells (apoptosis) and the role of neurotrophic factors

Answer 13

cells have death genes that are activated only to kill the cell. neurons compete for neurotrophic factors, ones that dont succeed go into apoptosis

Question 14

explain the chemoaffinity hypothesis

Answer 14

each cell has a chemical identity to guide the formation of synapses to proper target cells

Question 15

genotype

Answer 15

all of the genetic info of an individual

Question 16

phenotype

Answer 16

all of the physical characteristics of an individual

Question 17

mutation

Answer 17

change in genetic structure

Question 18

clones

Answer 18

genetically identical animals

Question 19

epigenetics

Answer 19

study of factors that affect gene expression without changing the nucleotide sequence of the genes

Question 20

teratogenic effects

Answer 20

effects of early exposure to toxins