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PSY1003 SEMESTER 2 > PSY1003 SEMESTER 2 WEEK 1 - part 1 > Flashcards

PSY1003 SEMESTER 2 WEEK 1 - part 1 Flashcards

1
Q

what is totipotent

A

ability to develop into any class of cell body, fertilised egg

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2
Q

what is pluripotent

A

able to develop to many but not all body cells, occurs when fertilised eggs start to specialise

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3
Q

what is multipotent

A

can only develop into different cell of one class

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4
Q

what is unipotent

A

develops into only one type of cell

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5
Q

what is a just-fertilised egg known as

A

zygote

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6
Q

explain development days 1-5

A

zygote divides to form morula (day 4)
day 5 = cells separate into 2 groups- inner mass (embryo) and encompassing sac (trophoblast- placenta), secreting fluid creating a cavity (blastocyst)

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7
Q

at day 5, an inner mass is formed. what 2 layers do the cells of the inner mass form

A

epiblast = embryo
hypoblast = becomes part of the gut

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8
Q

what happens at day 13-19 briefly describe

A

grastrulation, forming a 3 layer embryo and a groove/primitive streak by invaginationwha

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9
Q

what 3 layers are formed by the end of gastrulation (2-weeks) and how does this help form a neural plate

A

referred to as a gastrula
ectoderm: digestive system
mesoderm: bones, muscles, connective tissue
endoderm
the ectoderm thickens to become a neuroectoderm, forming a neural plate (induced by chemical signals from ‘organizser’- area of underlying mesoderm layer- beginning of nervous system)

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10
Q

define neural plate

A

small patch of ectodermal tissue on dorsal surface of developing embryo (often known as embryonic stem cells)

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11
Q

what are stem cell

A

unlimited capacity for self-renewal if maintained in appropriate cell culture, ability to develop into many different cell kinds

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12
Q

why does a stem cell have an unlimited capacity for self-renewing?

A

when a stem cell divides, it produces 2 daughter cells. one eventually develops into body cell, other develop into another stem cell

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13
Q

what causes neural folds during gastrulation and formation of neural plate

A

neural folds are increase in size of tissue between neural plate and rest of ectoderm. due to uneven rate of cell division forming groove

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14
Q

what occurs on day 20

A

ridges of ectoderm bulge over side and meet forming neural tube. tube cell start to proliferate

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15
Q

where does neural tube cell division normally occur?

A

in ventricular zone, with proliferation being controlled by chemical signals from 2 organiser areas in neural tube (floor plate- along midline of ventral surface of tube, and roof plate- runs along midline of dorsal surface of tube)
neural tube defect can occur, causing severe birth defects of CNS

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16
Q

what happens at day 22

A

interior of the neural tube becomes a fluid filled cerebral ventricles of the brain and spinal cord = neurula, known as “neurulation”

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17
Q

briefly describe migration

A

cells migrate to appropriate target location. still in an immature state, lacking processes such as axons and dendrites

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18
Q

name the 2 types of cell migration that can occur in a developing neural tube

A

radial and tangential

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19
Q

outline radial migration

A

from ventricular zone in straight line outward toward outer wall of tube

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20
Q

outline tangential migration

A

occurring at right angle to radial migration (parallel to tube wall)

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21
Q

what are the 2 developing cells migration

A

somal translocation, glia-mediated migration

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22
Q

outline somal translocation

A

extension grows from developing cell in direction of migration, looks for attractive or repulsive cues. cell body then moves into/along extending processes, then processes retract

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23
Q

outline glia-mediated migration

A

radial glial cells (network of glial cells) appear in developing neural tube and cells move along network to target. many radial glial cells develop into neurons

24
Q

explain inside-out pattern in migration

A

each wave of cortical cell migrate through already formed lower layers of cortex before reaching their destination

25
what is the neural crest?
dorsal to the neural tube, is formed by broken off cells from neural tube during development. develops into PNS neurons + glial cells
26
outline aggregation
post-migration aligning of developing neurons with other neurons in order to form structure
27
what mediate both migration/aggregation
CAM = cell-adhesion molecule
28
at day 24 the major 3 divisions of brain are visible. what are these
prosencephalon (telencephalon + diencephalon) mesencephalon rhombencephalon (metencephalon + myelencephalon)
29
outline how the neural tube becomes brain
channel between spinal cord and brain partially close, fluid pumped in to swell brain. at same time, cell division takes place gradually causing differentiation
30
what happens to brain development 3-4weeks
first bend around midbrain region, tilting the front of the tube away from basic orientation of rest of tube
31
what happens to brain development at 5 weeks
another bend, "cephalic flexure". telencephalic tube grows over rest of brain to form cerebral cortex. when it peels back, forms occipital and temporal lobes and takes fluid filled core with it, eventually forming ventricles
32
what happens to brain development at 6 months
early stage sulci and gyri of cerebral cortex
33
what occurs during gastrulation
cells in ectoderm around midline receive chemical signal, from notochord to develop to form neural precursor cells (neural stem cells = symmetrical proliferation). divide and produce another version of self
34
what is neuralation
follows gastrulation, precursors divide and produce primitive neuron (neuroblasts) or glial cell (glioblasts) and another precursor, mainly produced in ventricular zone
35
what do radial glial cells act as in migration
rails allowing the movement of neuroblast or glioblasts to their final destination, helped by guidance mechanisms such as glia or chemicals such as neuregulin
36
once neuroblasts or glioblasts reach their final destinations (via migration), what occurs?
decide what type of neurons/glial cells to become, determined by local chemical interactions with neighbouring cells
37
how are neuronal circuits formed
neuroblasts + glioblasts interconnect
38
outline axonal guidance
immature neurons initially produce number of small extensions (neurites), eventually one is axon and others dendrite. once axon is specialised, navigates to find target
39
what specialised terminals do axons use to find targets in axonal guidance
growth cones which consist of lamellipodia (sheet-like expansions) and filopodia (fine processes), and search for chemical which guides growths in particular direction
40
what do growth cones consist of
lamellipodia (sheet-like expansions) and filopodia (fine processes)
41
what do receptors in filopodia (found in growth cones) do
sense attractant/repellent chemical cues in environments
42
what 2 different type of agents do axonal growth cones use during navigating
diffusible agents (chemmoattractants/repellants, such as netrins) and nondiffusible agents (stuck to cell membrane of cell growth cone is crawling on (contact attractants/repellants)
42
define pioneer growth cones
1st growth cones to travel along particular route in developing nervous system follow correct trail by interacting with guidance molecules along route
43
what is fasciculation
neighbouring growth cones on same route follow the initial growth cone
44
define topographic gradient hypothesis
axons growing from one topographic surface (eg; retina) to another, are guided to specific target arranged on terminal surface in same way that axon's somas are arranged on original surface, suggesting growing axon guided to destination using 2 intersecting signal gradient
45
explain Sperrys frog study into the topographic gradient hypothesis
cut optic nerve of frog, rotated eyeball 180d, waited for axon of retinal ganglion cell to regenerate and dangled lure behind frog, struck forward suggesting their visual world also rotated, suggesting each retinal ganglion had grew back to same point of optic tectum (where originally was connected)
46
what is chemoaffinity hypothesis of axonal development (Sperry- from frog study)
each postsynaptic surface of nervous system release specific chemical label, each growing axon attracted by label to its postsyn target during development/regeneration ## Footnote not-essential
47
what does chemoaffinity hypothesis for axonal development fail to account
some growing axon follows same circuit route to reach targets in every individual instead of growing directly to it ## Footnote not-essential
48
how did Sperry revise chemoaffinity hypotheses
growth cones are influenced by series of chemical and physical signals along route ## Footnote not-essential
49
define neuron death
normal, and important part of neurodevelopment, produce 50% more neurons than needed
50
explain development of information on neuronal death
initially thought to be passive (necrosis) but now thought it is usually active, genetic programs inside neurons triggered to carry out apoptosis
51
outline why apoptosis more safe than necrosis
necrotic cells break and spill contents into extracellular fluid, causing harmful inflammation
52
what happens in apoptotic cell death
DNA and other internal structures cleaved apart, packaged in membranes before cell break apart and membrane contain molecules attracting microglia (preventing inflammation)
53
what illness could apoptosis cause?
when genetic program blocked, can cause cancer, if inappropriately activated, can cause neurodegenerative disease
54
give 2 triggers of apotosis in developing neurones
1. genetic programmes for early death (once completed functions, neuron groups dies) 2. developing neurons die as don't obtain life-preserving chemicals supplied by target neurotrophins like NCF (nerve growth factor) that promote neurons growth and survival, act as axon guidance molecules, stimulate synaptogenesis
55
describe what synapse rearrangement is
when die neuron leaves vacant spaces on postsynaptic membrane that are filled by sprouting axon terminals of surviving neurons. means cell death cause rearrangement of synaptic connections tending to focus output of each neuron on smaller number of postsynaptic cells, so increases transmission selectivity
56

PSY1003 SEMESTER 2 (10 decks)

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