Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
40 Cards in this Set
- Front
- Back
|
3 basic cellular elements of the CNS
|
Neurons
Neuroglia (astrocytes and oligodendrocytes) Other cellular elements (CT, blood vessels, microglia) |
|
|
What do primitive neuroepithelial cells of the neural tube give rise to?
|
Neuroblasts (which differentiate into neurons)
Glioblasts (differentiated into neuroglia and ependymal cells) |
|
|
What are gliomas?
|
Tumors that arise from astrocytes, oligodendrocytes, or ependymal cells
|
|
|
What organelles are specific to neurons?
|
Nissl bodies
Dendrites |
|
|
What are nissl bodies?
|
Prominent structures in the perikaryon which can be visualized at the light microscopic level with basic dyes called Nissl stains
|
|
|
What is the best known Nissl stain?
|
Cresyl violet
|
|
|
What do nissl stains stain? Why is it so prominent?
|
RNA and DNA
Contain more RNA in their cytoplasm than any other cell type in the body |
|
|
What are Nissl bodies made out of?
|
Stacks of rough endoplasmic reticulum
|
|
|
Describe the nucelus of neurons.
|
Usually spherical, in the center of the cell
|
|
|
What are dendrites?
|
True protoplasmic extensions of the cell body
|
|
|
Where do Nissl stains not stain on a neuron or why?
|
Dendrites don't stain - taper as they move away, Nissl bodies are too big to fit into dendrites
Axons - no ribosomes and no protein synthesizing capability |
|
|
How is it defined with a dendrite by EM?
|
Ribosomal presence
|
|
|
What are spines?
|
Protrusions of the dendritic surface that increase surface area
|
|
|
What things are present in the axons?
|
Mitochondria
Neurotubules Neurofilaments Smooth endoplasmic reticulum |
|
|
What are the 3 shapes of spines?
|
Thin
Mushroom Stubby |
|
|
What method is used to visualize dendrites?
|
Golgi silver impregnation method
|
|
|
How do you visualize axons? Give an example.
|
Myelin stains
Weigert stain |
|
|
How do you stain unmyelinated axons? Give the name.
|
Staining the neurofibrils
Ex. pyridine silver |
|
|
What occurs when axons of CNS neurons are damaged?
|
Neuron cell bodies undergo a retrograde response called chromatolysis. The color of Nissl staining is lysed b/c the cell imbibes water, and RNA is fragmented and becomes localized to the cell body periphery.
|
|
|
Where are inhibitory inputs on a cell located (usually) and why?
|
Inhibitor inputs are generally closer to the cell body. Synapses far out from the cell body on the dendritic tree have less influence than those closer to the cell body.
|
|
|
What is the purpose of spines?
|
Increase dendritic surface area
Isolate synaptic inputs |
|
|
What is immediately beneath a spine and why?
|
Ribosomes and/or ribosomal rosettes
Rapid synthesis of post-synaptic proteins |
|
|
How does shape affect the spine?
|
Presence of a significant 'neck' changes the resistance of the individual synapse.
|
|
|
Describe spines in young animals.
|
Majority are of the thin type.
|
|
|
Describe spines in adults.
|
Vast majority are of the mushroom or stubby type. Different rates of maturation for spines of neurons in different structures of the brain
|
|
|
Relation of SIDS and spines
|
Failure to lose spines in respiratory centers
|
|
|
Relationship between spines and intellectual disability
|
Spine dysgenesis - failure of the spines of cortical neurons to matur enormally. Especially Down's syndrome and Fragile X.
|
|
|
What 4 things characterize spine dysgenesis?
|
Failure to lose spines with maturity
Retention of long, immature spines Presence of abnormally thin spines with long necks and prominent terminal heads Absence of mature mushroom and stubby spine types |
|
|
What are telodendria?
|
Terminal endings of branchings of axons within target structures that are unmyelinated
|
|
|
How are neurons divided based on the length of their axons?
|
Long axons = Golgi type I
Short axons = Golgi type II (generally not myelinated) |
|
|
Golgi type I neurons: what fibers? maturation?
|
Commissural, long association, and projection fibers
Mature earlier than small 'interneurons' |
|
|
Golgi type II neurons: where are they especially abundant?
|
In associative areas in which the experience of the animal would be relevant to the maturation and function of the area
|
|
|
What characteristics define a synapse?
|
1. A presynaptic component with clustered synaptic vesicles at the active zone
2. A synaptic cleft or area of physical separation between the pre- and post-synaptic components 3. Presence of a postsynaptic density or area of the 'postsynaptic' component which has an undercoating of electron dense material |
|
|
What causes release of vesicles at the synapse?
|
Actoin potential depolarizes the membrane at the axons terminal causing Ca2+ to enter the pre-synaptic terminal. Induces the fusion of synaptic vesicles to the pre-synaptic membrane.
|
|
|
What are dense projections? What is their purpose?
|
Filamentous material on the presynaptic ending at the active zone. Vesicles are arranged in hexagonal arrays within this.
Believed to help anchor synaptic vesicles to the active zone in presynaptic terminals. |
|
|
What are the major excitatory and inhibitory neurotransmitters?
|
glutamate - excitatory
GABA - inhibitory |
|
|
Small, clear synaptic vesicles: 2 types?
|
Round vesicles
Pleomorphic vesicles |
|
|
Round vesicles: participate in? Correlated with?
|
Gray's Type I or asymmetric synapses
Excitatory synaptic transmission - glutamate |
|
|
Pleomorphic vesicles - participate in? associated with? type of transmission?
|
Gray's Type II or symmetrical synaptic contacts
Narrow synaptic cleft and an indistinct post-synaptic density Inhibitory synaptic transmission - GABA |
|
|
Dense core vesicles: neurotransmitters?
|
Very small - catecholamines
Larger - other amines (serotonin, histamine) Largest - neuropeptides |
