Chapter 8 Flashcards
Which gamete can contribute either and X or a Y
sperm
T/F Y chromosomes have a fraction of the genes compared to X chromosomes
True
SRY gene
a gene present of the Y chromosome which determines the sex of a human
What happens if the SRY gene is deleted?
XY fetuses develop female reproductive systems
What system develops and which degenerates in fetuses with SRY genes?
Wolffian system develops and Mullerian system degenerates
what is are the primordial reproductive systems?
Wolffian - male
Mullerian - female
T/F mammals have genotypic sex determination
True
What is the timeline for the zygote stage
0-2 weeks
what is the timeline of the embryonic stage
2-8 weeks
T/F there are large differences between vertebrates in the embryonic stage
F - they look alike as embryos and develop more distinct forms as they grow
What are the organizer tissue layers and what do they develop into?
Ectoderm - skin
Mesoderm - muscles and bone
Endoderm - digestive and respiratory
what is the first stage of nervous system development
neural plate stage in embryo
what is the second stage of nervous system development
neural tube stage, where the plate folds and forms a tube
what protects the nervous system during development
skin and bone encasement
what does the hollowed area of the neural tube become
the ventricles
Where does the peripheral nervous system develop from
neural crest
What are of the nervous system serves as a nursery for the rest of the developing CNS
neural tube
spina bifida
failure of the neural tube to close completely leaving a portion of the spinal cord uncovered
how is spina bifida fixed?
through surgery, though may result in paralysis
anencephaly
front end of the neural tube does not close leading to lack of forebrain development
how is anencephaly fixed
it is not fixable, will be fatal
when does fetal heart beat begin
35 days
where does stem cell proliferation occur
sub ventricular zone
what does it mean to say that stem cells are totipotent
they have the ability to become any kind of cell
what are the two daughter cells that are created by a dividing stem cell
one that is another stem cell
one that becomes what it needs to be
Subventricular zone
lining of neural stem cells surrounding the ventricles
progenitor cells
early version of a nervous system cell created from a stem cell
what can progenitors become?
neuroblasts (baby neurons) or glioblasts (baby glial cells)
T/F progenitor cells migrate out of the subventricular zone into their spot of the developing brain
F - progenitor cells develop into blasts before migrating
what are the two types of cell migration
radial and tangential
how many layers are in the neocortex
6 layers, with layer 6 being the deepest
which layer of the neocortex is developed first?
the 6th layer
what cell is responsible for radial migration
radial glial cells present during development
how do radial glial cell cause migration
they radiate out like spokes and developing cells move along the cell to their spot
what protein is responsible for tangential migration
reelin chemical signals
T/F after migration and aggregation, blasts develop into specific nervous system cells
true
why to neural cells aggregate
because they need to be near each other to make connections
how does cell differentiation occur
chemical signals activate specific genes which create proteins for specific cells
T/F cell differentiation is complete by birth
true
what are the two ways that neurons mature
axonal growth to nearby targets for synapse formation
dendritic growth to provide surface are of synapses
T/F dendritic growth occurs much faster than axon growth
F - axons much faster
growth cones
early axon terminals that support axon growth
filopod
sprouts from axon that search for potential synapses
synaptogenesis
creation of synapses between developed neurons
when can synaptogenesis occur
when neurons are developed
what leads growth cones and fasciculation
chemical signalling
fasciculation
creating synapses with a purpose
synaptic rearrangement
synaptic patterns become more focused later throughout to development
when do gyri and sulci begin to develop
8 months
what are the 2 types of cell death
necrosis and apoptosis
necrosis
cell dies and contents spill out, which can damage other nearby cells
apoptosis
controlled self-destruction
T/F Cell death is a necessary part of normal development
T
T/F Neuronal maturation slows after birth
F - continues through life
T/F Neurogenesis is mostly complete by birth
T
what determines the postnatal development of the brain
exposure
when does myelination occur
after the baby is born and continue through life
what are the main areas of brain development in babies
primary visual and auditory cortices
what area of the brain lags behind during development, as it tends to develop last
the prefrontal cortex
T/F Synaptogenesis spikes after birth, then pruning begins in first year and synapses decrease
True
Neural Darwinism
survival of useful synapses only as too many synapses will waste nutrition
