Neurosensory Systems Flashcards
Nuerological disorders are characterized by
physical manifestations
Psychiatric disorders are more:
Internal disorders so disruption of mental processes
Neuron can repair if damage is slight by:
regrow damaged dendrites or axons by “sprouting” and regrowth
Neurons are:
Post-mitotic, so if it dies, it cannot be replaced
CNS disorders
Neurons that can regenerate are:
olfactory neurons and hippocampal dentate gyrus neurons
Astrocytes
Can be regenerated
During neuronal degenration they become reactive
Help clear cellular debris and seal off damaged regions through glial scar
Participate in neuroinflammation by releasing cytokines and related agents
Microglia
Respond to neurodegeneration
Secrete cytokines and chemokines to clear debris
Can be regenrated
Oligodendrocytes
When killed or damage = demyelination of axons impairing neuronal signaling
Test abnormal function through
PET/SPECT
See abnormal CNS structure through
CAT scans or MRI
Define elctrophysiology
Elecrodes are inserted into the brain to monitor the electrical activity of the regions
Can record activity or stimulate
Define electroencephalography (EEG)
Electrodes placed on the surface of the scalp to record electrical activity occurring in the brain
Brain relaxes =
Frequency decreases and amplitude increases
Define CT Scanning
Xrays
Attenuated varying degrees in a manner dependent on the tissue density
Data is converted to tissue density
STRUCTURAL ANALYSIS
Define Positron Emission Tomography (PET)
Detectors -> exact location of the positron annihilation and the location of the molecule of interest
BLOOD FLOW
Label an agent with PE isotopes and inject so you can measure the concentration of receptors at various regions in the brain
Increased neuronal activity –>
Local increase in blood flow supply the metabolic demands of those neurons
PET is used for
dementia and PK disease (dopamine transporters in the striatum)
Define Magnetic Resonance Imaging (MRI)
WATER CONTENT
Define Functional MRI (fMRI)
Monitors time-dependent blood flow to various region sin the brain and thus allows one to ID neuronally active regions
Define functional hyperemia
Local flow around an active neuron is altered to meet local metabolic demands
Signal is greater=
Parallel bc water molecules line up in the direction of the axons
How much O2 does the brain consume?
20%
Brain + disruption of blood flow
Sensitive and it only stakes a short disruption to impair neuronal function of ultimately lead to celld eath
Astrocytes + Backup
Make small amounts of glycogen as bacjup energy
Define selective vulnerability
The pattern of neurologic deficits that arise causing a specific disease
Define gliosis
Hypertrophy or multiplication of glial cells
Define Reactive gliosis
Normal response to CNS injury
What cells are particularly sensitive to glutamate?
Pyramidal neurons in cerebral cortex
Glutamate + toxicity
Glutamate binding to NMDA receptor on neurons which allows influx of calcium which can trigger apoptotic pathways
Can some cells prevent toxicity?
Yes some have proteins like calbindin which bind and buffer the calcium
Glutamate + Cell death
Glutamate opens AMPA channels –> too much sodium which increase pressure, influx of water, swelling and bursting
This induces neuroinflammation and activation of reactive astrocytes and microglia
ROS production
Astrocytes and microglia can produce ROS to breakdown tissues and repair
