Nervous Flashcards
2 types of cells in neurons?
Neurons - excitable cells - transmit electrical signals
Neuroglia - nonexcitable cells - support, surround, wrap around neurons
Nervous tissue develops from?
Neural tube and neural crest cells
Neuron stem cells located?
Lateral ventricles
Hippocampus
Olfactory region
Neuron theory and if die?
Independent chain - not influence by other chains
If die, not replaced - post mitotic - highly differentiated
Length of axon. Longest axon. Cell body size?
1mm-1m. 1m = sciatic nerve
Cell body - 4-135um
Peripheral nervous system (3)
Central nervous system (2)
Hollow organs, nerves, ganglia
Brain (grey matter), spinal chord(csf)
3 types of neurons?
Unipolar
Pseudounipolar
Bipolar
Neuron Axon length classification? (3)
Golgi 1 - long axon - being from grey matter Golgi 2 (no or shorter axon) - not send out branches to grey matter
Developed animals - greater amount of golgi 1
Functional classification of neurons (3)
Sensory, motor, interneurons (99%)
Motor neurons can be ?
Inhibitory or stimulatory
Unipolar neuron?
One prolongement
less common in vertebrates
Bipolar neuron
1 dendrite
1 axon
Pseudounipolar
Sensory gangila, dorsal root gangila
Dendrites? Structural(4) detected by (2) max length(1)
Cytoplasmic prolongements.
Branched. Thinner away from body.
Dendritic spines - receive synapses -Detected by florescent staining.
- EM microscope.
Max length 700um
Specific stain for neurons? (2) cytoskeleton and nissl bodies?
Cytoskeleton - gold staining
Nissyl bodies - rer polyribosomes - basic staining eg - h and e.
Organelles in neurons
Mito, rer, ser, nissl bodies, golgi, nucleus, nucleolus, mt, int filaments (neurofilaments), actin filaments, lipofucins (increase with age)
Mito in neurons?
Neurons in terms of mitosis?
What increases with age because of this?
Longi cisternae.
Post mitotic.
Increase of Iipofucins with age
What lacks in dendrites and nissl body staining?
Ser
Basic staining - basophillic due to rer and polyribosomes
Axon. Function. Length. Diammeter. Sheath. Cytoplasm. Filaments. Organelles
Info to periphery.
Long 1mm to 1m
Uniform diameter, eventually collateral
Simple or complex sheath ( myelin sheath or neurilemma)
Cytoplasm (axoplasm,). Neurofilaments parallel to axis, mt, actin
No organelles involved in protein syn eg rer. Large no of mito
Dendrites and axon differences
Dendrites
Ribosomes, rer. Non uniform. No sheath, irregular. Shorter and branches.
Axon
No organelles in protein syn. Uniform diammeter. Long. Not branched. Sheath. Large no of mito
Neurofilaments, mt, actin filaments function in neurons?
Neuro Filaments - int filaments - support
Mt - axonal flux regulation
Microfilaments - actin - longi and circ arrangement - rel of net and axonal transport
Axonal transport. Motor proteins. And 2 types of transport in terms of speed
Kinesin +, dyenin - map
Fast 50-400mm/day- antero - away - protein, organelles, veesicles
- vesicles pm renewal, organelles to be destroyed
Slow - 1mm / day cytoskeleton, cytoplasmic subunits
What type of transport is herpes virus?
Reterograde
Glial cells in pns and cn - cell body
Glial cells - CNS
Satellite cells - PNS
Glial cells - neuron - axon
Axon - myelin sheath - neurolemma
Schwann cells - PNS
Oligodendrocytes - CNS - connect to multiple neurons
Nerve fibre pns
Unmylinated - pale staining - one Schwann cell interacting with more than one axon - actin fil, mt inside axon
Myelinated - Schwann cell wrapped around axon - schmitt-lantermann clefts
Layers surrounding axon
Em microscope see ->
Int ext mesaaxon
Em microscope - internodal segment (100-200um)
Fibres of cns?
Glial cells - oligodendrocytes - large no of prolongements - wrap around multiple axons
Major dense line
Adheion of inner pm
Represents adhesion of inner layer of schwnn cells
Intraperiod line
Represent adhesion of outer layer of pm
Myeline pathologies
Immune system - auto antibodies - destroyed plp (protolipid protein) mpb(myelin basic protein)
Responsible - myeline degeneration -> multiple sclerosis
Myeline sheath function (3)
Insulation, saltatory conduction, nerve regen
Schmitt-lanterman clefts
Irregularities in pm due to cytoplasm of schwann cell
Myelinated - pns and cns
Pns - white matter + initial tract of nerves
Cns - spinal and cranial nerves
Unmylinated areas
Nodes of ranvir
Tactile afferents
Presynaptic membrane - ser?
Reprocess endocytotic vesicles -> synaptic vesicles
1 neuron connected to max?
10000 synapses
Synapses are?
Chemical(diffusion) or electrical(gap junctions)
Unidirectional
Synaptic cleft approx size?
25um
Different types of synapses?
Axosomatic
Axoaxonic
Axodentritic
Dendrodentritic
Proteins in pre-synaptic membrane?
Synapsin 1(connector protein of synaptic vesicles to fodrin filaments) Fodrin (filamentous protein)
Pre-synaptic grid?
Post-synaptic ?
Actin filaments
Electron dense layer
How calcium effects vesicle release in presynaptic membrane?
Depolarisation - ca channels open - ca bind to calmodulin - active protein kinase - phosphorylation of synapsin - lose affinity for vesicles and fodrin - vesicles released - v snare on vesicles bind to t snare on presynaptic membrane - endocytosis
2 types of synapse
type one - asymmetric - wide cleft - post syn thicker - excitatory
Type 2 - symmetric - equal thickness of post and pre - inhibitory
Example of NETs (9)
Ach, serotonin, gaba, dopamine, norepinephine, epinephine, endorphins, glycine, no
Ganglion
All body of neurone with satellite cells
Glia (5)
Non excitable 49% of cells in nervous Proliferate - involved in tumours Synapse stabilisation Support neurons - mechanical, metabolic support. Delivery of nutrients
Pns and cells (2) in cross section and nucleus
Schwann and satellite cells
Nerves and ganglia
Cross section - rounded
Nucleus - nucleuolus
Central nervous system (4)
Ependymal cells - line cavities + spaces
Astrocytes - many prolongements - blood brain barrier - protect brain
Oligodendrocytes - myeline sheath -wrap around multiple neurons
Microglia - from monocytes - phagocytosis
Schwann cells and nerve regen
And when only possible
Damage to terminal axon
Macrophages/microglia - distal part of damaged nerve - remove cell debris
Schwann cells proliferate - proximal part
Only possible if no damage to cell body
Ependymal cells (5)
Apical - cilia Produce csf Line ventricles, cavities and spaces Similar to epithelial cells May function of stem cells
Astrocytes shape and where abudant?
Star shaped and thinly branched
CNS
Specific marker for astrocyte is?
GFAP - Int, filament.
Down Regulated during pathology
2 types of astrocytes and where found.
Fibrous - white matter - straight, fewer processes
Protoplasmic - grey matter - numerous short branching processes
Function of astrocytes (4)
Structural support, repair of scar tissue, phagocytosis, reg. of met blood brain barrier
Ananolog of oligodenrocytes in pns?
Schwann cells
Oligodendrocytes?
Found in cns. 70% of glial cells
Multiple axon form myeline sheath.
Rounded nucleus, abundant golgi
Microglia
Monocyte linage. Phagocytosis
Large no of lysoosmes, lipofucins, vesicles.
Little mt and rer
Microglia and pathologies
Involved in inflammatory pathology of brain - contribute to neural pathologies.
Microglia - flattened nuclei - difficult to distinguish.
Blood brain barrier? Ans other examples
Formed by astrocytes. Protoplasmic - grey matter Fibrous - white matter Perivascular feet - separate blood vessels from neuron. Thymus, testis, air.
Cross section of blood brain barrier (3)
How different to capp?
Thin endothelial cells - on basal lamina
Epithelial cells connected by - occluding junctions - zo1-2 proteins.
Req specific carrier/transporter - specific mat.
Capp contain pores - no gap junctions
Catecholamine net, amino acid net?
Synth from tyrosine - Dopamine, adrenaline, noradrenaline
Aa (mainly cns)- glycine, aspartate, gaba, glutamate
Post synaptic sympathetic nervous system net (ans)?
Adrenaline.
Synapse convert nor into adrenaline = adrenergic via enzymes
Shwann cell wrapping 4 areas of note?
Intra period line - extracellular space
Major dense line - cytoplasm of shwann cell
Inner and outer mesaxon
Thickness of myeline sheath determined by?
Diameter of axon and NOT schwann cell
Function of satellite cell and where found.
Form complete layer around cell bodies ganglia
Surrounded by small cuboidal cells - satellite cells.
Maintain microenvironment around cell body,
insulation,
pathway for met exchanges
Analog of schwann in pns?
Satellite cells
