Neuronal Death

Question 1

what are 6 reasons neurons die?

Answer 1

we dont need
served their purpose
error correction
pattern formation
size matching
removal of damaged or harmful cells

Question 2

what is the most apparent explanation for removing cells we do not need?

Answer 2

sexual dimorphism in the CNA

Question 3

describe sexual dimorphism in the CNA

Answer 3

anteroventral periventricular nucleus more cell dense in female rodents, and irrespective of male or female- same number of cells created so males must lose cells during developemtn

Question 4

describe an example of when cells die post to serving their purpose

Answer 4

in species that undergo metamorphosis

tadpoles have tails and frogs have legs- so neurons critical to tadpoles die off when frog becomes mature

Question 5

what is error correction?

Answer 5

removal of neurons that have not connected with the correct targets

Question 6

what is an example of error correction?

Answer 6

eyes
projections going to wrong eye are eliminated
there is regulation and if neurites take wrong turn, they die off by apoptosis

Question 7

what is the order of pattern formation?

Answer 7

NS begins as flat sheet of cells -> neural tube -> complex shaping manaouvers -> brain and NS

Question 8

what is the best example of pattern formation?

Answer 8

hand

in ducks formation stops earlier- skin between fingers remains

Question 9

what is an advantage of size matching?

Answer 9

evolutionary

Question 10

describe removal of damaged or harmful cells

Answer 10

very rare
defence against pathogens
neuron under attack from rabies

Question 11

what are 5 diseases involving unwanted neuronal loss

Answer 11

parkinsons
alzheimers
huntingtons
stroke
mad cow disease

Question 12

describe neural loss in parkinsons

Answer 12

pigmented cells that synthesise dopamine in healthy brain- has been lost
loss of l dopa

Question 13

describe neural loss in alzheimers

Answer 13

overall loss of brain mass

Question 14

describe neural loss in huntintons

Answer 14

loss portions of striatum

Question 15

describe neural loss from a strokw

Answer 15

areas around blood clot or bleed are extreme damage or loss

Question 16

describe neural loss in mad cow disease

Answer 16

brain spongey

Question 17

how do neurons die

Answer 17

apoptosis

necrosis/necroptosis

Question 18

what is apoptosis

Answer 18

sporadic loss of cells
no inflammatory response
theres a tipping point for speed

Question 19

what are 6 triggers of neuronal apoptosis

Answer 19

neurotrophic factor deprivation
excitotoxity - excess glutamate
metamorphosis
neurodegeneration
exposure to UV
deleterious effects of reactive oxygen species

Question 20

describe excitotoxicity

Answer 20

excess glutamate
glutamate neurotransmitter and so is substance that makes neurons produce electrical signals, too much leads to too excited neurons leading to cell death

Question 21

what are 6 characteristics of apoptosis

Answer 21

cells shrink in size
nuclear chromatin condenses
dna has laddered appearanc
cell membrane and organelles stay relatively in tact
cytoplasm and nucleus make many apoptopic bodies
apoptopic bodies are phagocytosed(no immune response)

Question 22

what is necrosis

Answer 22

accidental or pathological injury causes rapid cell death- extracellular signalling may be involved too (necropotis)
initiates an immune response

Question 23

what stresses can induce necrosis

Answer 23

environmental(heat, infection, O2 deprivation)
extracellular signals (receptor, transduction and response, often termed necroptosis)

Question 24

what are the characteristics of necrosis

Answer 24

cell swelling and metabolic failure
disintegration of cell membrane and organelles
immune reaction

Question 25

what is pyknosis

Answer 25

chromatin condensation patter in apoptosis

Question 26

what is necroptosis

Answer 26

extracellular signals mediate necrosis

mediated by death receptor

Question 27

what are the two death receptors associated with necroptosis

Answer 27

TNF and Fas-L

Question 28

what is the necrosome

Answer 28

biochemical pathway crucial for necroptosis

Question 29

what is the deciding point of necrosome

Answer 29

RIP1 a protein
polyubiquitinated
cell death signal chops the poly ubiquitin tail off and it binds to caspase 8