Neurodegeneration Flashcards
what are the 4 mechanisms of neurological disorders?
Autophagy
oxidative stress
apoptosis
necrosis
what is autophagy
the normal housekeepings of a cell to maintain function of neurons
what is another function of autophagy?
it acts to recycle proteins, lipids and nucleic acids through lysosomes
what are lysosomes?
Membrane bound organelles containing an array of hydrolytic enzymes
function of hydrolytic enzymes
they deal with a range of substrates transported into the lysosomes via invagination or across the membrane
what are the 4 processes of autophagy?
eliminating waste
protect against variations of nutrient availabilities
promoting cellular remodelling
protection against invading pathogens.
how do toxic substrates accumulate in autophagy?
when these housekeeping functions in the neurons become disordered or unbalanced.
How does oxidative stress arise?
arises from reactive oxygen species (ROS) which are hydrogen peroxide, hydroxyl and superoxide.
what can oxidative stress lead to?
oxidative damage within nerve cells.
What does ROS stand for?
Reactive Oxygen Species
What are ROS products of?
they are products of mitochondrial energy production in very low levels.
What happens if the mitochondria develop any defects?
then the production of ROS will increase which can lead to some denaturation of some proteins.
How then can a toxic substrate form as a result of oxidative stress?
after the denaturation of a protein some may be repaired, if the repair misfolds then a toxic element may be produced which can collect within the cell.
what effect does the production of toxic elements collecting within the cell have on the neuron?
causes the neuron to misfunction or more likely be destroyed.
What is Apoptosis?
the cellular mechanism for orderly destruction.
describe stage 1 of Apoptosis
It is triggered within the cell which then starts of a proteolytic cascade of reactions
what is the result of this cascade of reactions?
the cell contents dismantles leading to cell shrinkage which causes the cell to become a target for phagocytosis by macrophage.
What does this mean for the person?
it causes a huge loss of neuron is the nervous system that wont be replaced.
what is neuronal plasticity?
the rewiring of remaining neurons
what role does neuronal plasticity play in apoptosis?
neuronal plasticity compensates for the loss of neurons in the nervous system to a great extent.
What is Necrosis?
it is a process of cell death involving overt damage to cells initiating an inflammatory response and a clean up by the immune system.
what contribution to neurodegeneration does necrosis have?
contributes to the loss of neurons and the progression of disease pathology
What damage is Necrosis associated with?
cellular injury
inflammation
damage to neighbouring cells
name 2 conditions that can cause necrosis to occur
- Stroke
- ischemic Injury
