Exam #2: Nerve Flashcards
Neuron
Basic structural & functional unit of the nervous system
What type of neuron has an angular cell body?
Multipolar
What type of neuron has an ovoid cell body?
Bipolar
What type of neuron has a spherical cell body?
Pseudo-unipolar
Perikaryon
Cell body
Multipolar Neuron
- Most common type of neuron in the body
- Euchromatic nucleus (protein synthesis is constant)
- Dark nucleolus
- Nissil bodies
Nissil Bodies
Stacks of rER that look like clumps
Microtubules
Skeleton of the neuron
Neurofilaments
Muscles of the neuron b/c of contractile properties
Axon Hillock
- Proximal end of the axon
- Funnel-shaped
- Pale staining b/c lacking rER
- Contains microtubules & microfilaments
Lipofuscin
- Old degenerated plasma membrane that cannot be fully degraded by lysosomes & accumulates in the cytoplasm
- Accumulates with age
Neuromelanin
Byproduct of DA synthesis (Substantia Nigra)
Dendrites
Increase the receptive surface area of the neuron
Terminal Bouton
Swollen dilated portions of the axon in with presynaptic terminals
Initial Segment
Part of the axon where the nerve terminal is generated
Myelin
- Increases conduction velocity
- Insulates axons
Does the axon contain rER?
NO!
Anterograde Transport
- Flow of substances away from the cell body
- Kinesin micotubule motor protein
- Slow= No ATP
- Fast= ATP
What substances are transported via slow anterograde transport?
- Tubulin
- Actin
- Neurofilament proteins
Retrograde Transport
- Flow of substances from the axon terminal to the cell body
- Dynein mitrotubule motor protein
- Fast Transport only (ATP)
- Viruses & toxins
What substances are transported via fast retorgrade transport?
- sER
- Vesicles
- Mitochondria
- Amino Acids
- Sugars
- Nucleotides
- Ca++
Bipolar Neuron
- Associated with the special senses (vision, hearing, balance, smell)
- Dendrite in the periphery
- Axon terminates in brainstem
Pseudo-unipolar
- Cell body is located in sensory ganglia
- Axon terminal is in the brainstem
- E.g. Cranial Nerves
Afferent
Sensory (toward)
Efferent
Motor (away)
Astrocytes
- Start shaped with astrocytic feet that cover the surface of capillaries
- Form the BBB
- Form scar tissue in response to a lesion
- Monitor ionic & chemical composition of the CSF
Microglia
- Phagocytic cells of the nervous system
- Derived from monocytes
Astrocytoma
- Most common type of brain tumor
- Arises from astrocytes
- Deforms ventricles
Ependymal Cells
Type of neuroglia that lines the ventricles
Ependymoma
- Tumor of the 4th ventricle that compresses the surrounding structures
- Rare type of tumor that arises from ependymal cells
Unmyelinated axon in the CNS
“naked”
Unmyelinated axon in the PNS
Sit in a Schwann cell groove
Oligodendrocytes
- Myelinate axons in the CNS
- 3 foot-like processes myeliante 3 axons
Schwann Cells
- Myelinate axons in the PNS
- Myelinate 1-to-1
Myelin
- Fatty & white b/c of lipid content (Lipoprotein)
- NOT secreted; rather, wraps around the axons
Internode
Myelinated portion of an axons
Node of Ranvier
Gap between two internodes
Clefts of Schmidt-Lanterman
Schwann cell cytoplasm that gets trapped in the concentric layers of the call membrane myelinating the axon
Endoneurium
- Connective tissue surrounding individual axons in the PNS
- Contains collagen
Perineurium
Connective tissue surrounding a fascile in the PNS
Epineurium
- Connective tissue surrounding an entire nerve in the PNS
- Dense irregular collagenous tissue sleeve
- Contains blood & lymphatic vessels
Papilledema
Swelling of the optic disc
Optic Neuritis
Inflammation of the optic nerve
- Presents with papilledema
- Most common cause is MS
Multiple Sclerosis
- Autoantibodies generated against oligodendrocytes
- Triggered by oligodendrogliopathy
Nucleus
Collection of nerve cell bodies within the CNS
Gray Matter
- Cerebellar Cortex & Cerebral Cortex
- Nuclei deep to Cerebral Cortex
- Nerve cell bodies
White Matter
- Myelinated axons
- Tracts
- Nerve cell axons
How many pairs of cranial nerves are there?
12
How many pairs of spinal nerves are there?
31
Voluntary Nervous System
Brain, spinal cord, motor neurons in peripheral nerves
Involuntary Nervous System
ANS
Sympathetic Nervous System
- Thoracolumbar outflow
- T1–>L2-3
Parasympathetic Nervous System
- Craniosacral outflow
Axodendritic
- most common type of synapse
- axon terminal & dendrite
Axosomatic
Synapse between an axon terminal & membrane of a cell body
Axoaxonic
- Least frequent type of synapse
- Synapse between two axon terminals
Kiss & Run
Brief attachment & release of only a portion of the contents of a vesicle
Collapse
Vesicle attaches & completely empties all of its contents into the synaptic cleft
Describe the flow of CSF
1) Choroid Plexus
2) 2x lateral ventricles
3) 3rd Ventricle
4) Cerebral Aqueduct of Sylvius
5) 4th Ventricle
6) Most leaks into the subarachnoid space
7) Remainder goes into the central canal of the spinal cord
Arachnoid Granulation
Many arachnoid villi
Anterograde Changes in Response to Injury
- Distal segment of axon degenerates
- Elimination of debris by phagocytic cells (Schwann cells & macrophages)
- Schwann cells form tunnels for the axon sprouts to go through
Retrograde Changes in Response to Injury
- Swelling of the cell body
- Chromatolysis (Nissil bodies & rER breakdown/ nucleus moves aside)
- Protein synthesis
- Nucleus moves back
- Axon sprouts
Fibrous Astrocytes
White Matter
Protoplasmic Astrocytes
Gray Matter
