Aging and Development Flashcards
Neurogenesis
Cells of the neural tube divide to create either progenitor or neuron close to neural tube
Radial glial cells
Glia that extend from inner to outer surfaces of growing NS like spokes of a wheel
Cell migration
Cells that form in the ventricular layer migrate along the surface of radial glial cells
Cell adhesion molecules
Protein that guides cell migration and promotes adhesion of developing NS; an example of cell-cell interactions
Differentiation
Cells express genes to make proteins that allow them to acquire their specific appearance and function
Experimental data of differentiation
The development of different types of neurons seen in early development
Induction in differentiation
The influence of neighboring cells on other adjacent cells
Example of induction
The notochord releasing dorsalizing or ventralizing hormones which determines whether a neuron is sensory or motor
Regulation
A benefit of induction which allows an adaptive response to early cell injury
Synaptogenesis
Establishment of synaptic connections as axons and dendrites form
Growth cones
Growing tip of an axon or dendrite
Filopodia
Fine extensions that extend from growth cone
What role do CAM play in synaptogenesis
Filopodia adhere to CAM released by target nerve cells/tissues, and contract to pull the growth cone in a certain direction
Chemoattractants and chemorepellants
Chemoattractants attract certain growth cones while chemorepellants do the opposite
Why do we have chemorepellants
Some axons need to stay ipsilateral, so chemorepellants can keep them from crossing the midline
Chemoaffinity
A theory for synaptogenesis that states that each cell and target cell have matching chemical identities that guide filopodias
Death gene
A gene expressed when a cell decides to commit suicide
Caspase
An family of protein-dissolving enzymes that regulate apoptosis
Diablo
Released by mitochondria in response to high calcium levels
What is the process of cell death
- Increase in [Ca2+] from extra and intracellular sources
- High levels of calcium reach the mitochondria and release Diablo protein into cell
- Diablo binds to an apoptosis inhibitor protein
- Caspases are no longer blocked, which leads to apoptosis
BcI-2 proteins
Proteins that block apoptosis
Neurotrophic factors
A chemical made by target structure. If a neuron receives enough neurotrophic factor, it will live and otherwise die
Nerve growth factor
Affects the growth of neurons in spinal ganglia and ganglia of sympathetic NS
Mechanism of neurotrophic factors
- Neurotrophic factors regulate the expression of various genes which affect neuron development
- Neurons that don’t get enough trophic factor go through cell death
- Amount of neurotrophic factor in cell matches target cell which creates synapse
Why does the prefrontal cortex develop last
Synapse rearrangement reoccurs caudal to rostrally
Monocular deprivation of cats
Light shone in the deprived eye results in no cell response, while light shone in the normal eye results in normal cell response
One eye deviation in cats
Cortical cells only respond to stimulation in one eye or the other
Hebbian synapses
Synapses that grow stronger or weaker depending on how it drives the postsynaptic cell
Where are multimodal cells found
Deep in superior colliculi
Two categories of biological theories of aging
Programmed theory and damage/error theory
Three theories of programmed aging
Aging by program, gene theory, autoimmune theory
Cholinergic dysfunctions
-Decreased ChAT which catalyzes synthesis of ACh
- Decreased cholinergic neurons
Function of scopalamine
An ACh antagonist that artificially disrupts cholinergic function in young subjects and creates impairments similar to the elderly
Superoxide
When an oxygen radical receives energy
Defense against superoxides
Superoxide dismutase breaks down the superoxide into hydrogen peroxide and oxygen
Superoxide damage to cell
Can cause DNA damage in the nucleus & mitochondria and cause cell membrane damage
Relationship between free radicals and nerve growth factor
Nerve growth factor suppresses free radical activity
What causes cell loss
Could be glia, but it’s definitely not neurons
Beta amyloid
Protein that accumulates in small areas of the brain that have abnormal patterns
Tau tangles
Tau is a protein associated with abnormal spirals within nerve cells
What happens with acetylcholine production in Alzheimer’s
Tau tangles and amyloid plates lead to cholinergic neurons to stop producing ACh
