CNS Cell Types Flashcards
Defects in the following neural systems results in which disorder?
- sensory defects
- motor defects
- associative defects
- sensory defects - neuropathies
- motor defects - movement disorders
- associative defects - cognitive decline
what are the two main CNS cell types?
neurons and glia
how many and what are the types of differentiated glia?
there are 3 types:
- oligodendrocytes
- microglia
- astrocytes
name some other CNS cell types apart from neutrons and differentiated glia?
- glial stem cells
- oligodendrocytes precursors
- ependymal cells
Neurons are exclusively formed during brain development
- True
- False
False, neurons are mainly formed during brain development but not exclusively
what is the prime role of neurons?
it is specialised for intercellular communication and electrical signalling via synapses
how do the neurons communicate via synapses?
- dendrites receive inputs (dendritic spines)
- transmit the signal to cell body (soma)
- action potentials propagate along axons from axons hillock
A real neuron is a tissue section
- True
- False
True
what are the two ways via which neurons communicate?
- chemical - majority
2. electrical - allow synchronized electrical activity- brainstem neurons, breathing- hypothalamus, hormone secretion
synapses are concentrated on dendritic spines
- True
- False
True
why is neural plasticity significant and its role in neural diseases?
- it forms the basis of learning and memory
- spine remodelling is linked to neural activity
- it is highly relevant to diseases like AD, SZ
give an example to illustrate neuronal heterogeneity
- Upper motor neurons – large, excitatory, glutamatergic, long projections, pyramidal
- Striatal interneurons – small, spiny, inhibitory, GABAergic
what is arborisation of axons and dendrites?
a fine branching structure at the end of a nerve fibre
what are the features of oligodendrocytes and the significance of myelin sheath to OG?
- unique to vertebrates
- myelinating cells of CNS
- provides metabolic support for axons
- myelin insulated axon segments, bales rapid nerve conduction
- myelin sheath segments interrupted by nodes of Ranvier - saltatory conduction
- demyelinating diseases e.g. multiple sclerosis
what does oligodendrocytes look like in histology?
appear like fried egg
- how is myelin sheath formed?
- what is its composition?
- name few myelin specific proteins and its function?
- formed by wrapping of axons by oligodendrocytes processes (membranes)
- they are highly compact - 70% lipid and 30% protein
- myelin specific proteins - MAG,MOG, MBP, PLP, PMP22 - mainly involved in compaction, excellent markers
what are the features of microglia?
- resident of immune cells in CNS
- derived from erythromyeloid progenitors that migrate into CNS up to ~P10 in rodents
- resting state - highly ramified, motile processes, survey environment (2-3µm/min)
- Upon activation (e.g. by ATP), retract processes, become “amoeboid” & motile
- Proliferate at sites of injury - phagocytic
what is the function of microglia?
- Immune surveillance
- Phagocytosis – debris/microbes
- Synaptic plasticity –pruning
- Process dynamics
do normal microglia differ in appearance in cortex and white matter? if so, how?
yes, they are ramified in cortex and more bilaterally branded in the white matter
what is the difference between good and bad microglia?
good microglia - ↓inflammation and ↑phagocytosis
bad microglia - ↑inflammation and ↓phagocytosis
what are the features of astrocytes?
- “Star-like cells”
- Highly heterogeneous – not all star-shaped
- Most numerous glial cells in the CNS
- Common “marker” glial fibrillary acidic protein (GFAP)
what are the two types of astrocytes?
- Fibrous – white matter, less elaborate, processes contacts as below & with nodes of Ranvier
- Protoplasmic – grey matter, extremely elaborate, processes contact blood vessels & pial surface
what are the physical differences of fibrous astrocyte and protoplasmic astrocyte?
fibrous - long branches and less bifurcation (less elaborate)
protoplasmic - shorter branches but more ramified (extremely elaborate)
what are the functions of astrocytes?
- Developmental – radial glia
- Structural - define brain micro-architecture
- Envelope synapses – “tripartite synapse”
- Homeostatic – buffer K+, glutamate, etc.
- Support neurons - Glutamate-Glutamine shuttle, lactate shuttle, etc.
- Neurovascular coupling (basis of fMRI)
- Disease relevance – gliosis/astrocytosis
