Download HCB Objectives 9

HCB Objectives 9
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Note: Peripheral synapses have basal lamina; Central don’t.
1.
Structures of:
a.
Cerebellum: Contains 3 layers: outermost molecular layer (unmyelinated
fibers), Purkinje cell layer (Purkinje cells), and granular cell layer
(cellular)
b.
Cerebral cortex: Contains 6 layers: Outermost molecular layer
(dendrites, axons, and horizontal cells), outer granular layer (dense
collection of small pyramidal cells an stellate cells), pyramidal layer
(pyramidal cells increasing in size from superficial to deep), inner granular
layer (dense collection of stellate cells), ganglionic layer (large pyramidal
cells, few stellate cells, and cells of Martinotti), and multiform cell layer
(wide variety of cells)
c.
Spinal cord: grey matter is eosinophilic, and resides on the inside; at
times, the dorsal nerve roots can be seen as well as specific structures
correlating to the level of spinal section
d.
Dorsal root ganglia: Large spherical cell bodies, prominent nuclei and
nucleoli, cells have a “fried egg” appearance, cells are large so nuclei
aren’t often present in section, pseudounipolar cells.
e.
Sympathetic ganglia: Small cell bodies, prominent nuclei and nucleoli,
neuron cells are smaller than dorsal root ganglia so nuclei are often
present, multipolar cells.
f.
Parasympathetic ganglia: Cell bodies are found in the walls of the organs
they innervate, multipolar cells.
g.
Peripheral nerve: composed of nerve fascicles and epineurium (dense CT
surrounding nerve), perineurium (loose CT surrounding fascicles with
tight junctions), and endoneurium (loose CT made of reticular fibers
within the fascicle)
2.
Components of a peripheral nerve:
a.
Epineurium: Outermost sheath, made of dense CT (dura mater), fills the
spaces between nerve fascicles and allows bloodstream to flow through
b.
Perineurium: Surrounds each nerve fascicle, flattened cells joined by tight
junctions, may maintain ionic balance of extracellular fluid within the
nerve
c.
Endoneurium: Within the nerve fascicle, separating individual axons and
their Schwann cell sheaths
3.
Locations and functions of:
a.
Purkinje cells:
a. Location: In the cerebellar Purkinje cell layer
b. Function: Main output cells of the cerebellum
b.
Granule cells:
a. Location: In the cerebellar granular layer and cortical layer 2, 4, 5,
and 6
b. Function: Main target of ascending axons entering the cerebellum;
send axons to Punkinje cells
c.
Pyramidal cortex cells:
a. Location: In cortical layers 2, 3, 5, and 6
b. Function: Major output cells of neocortex
d.
Nonpyramidal cortex cells:
a. Location: In cortical layers 1, 2, 4, 5, and 6
b. Function: To influence pyramidal cortex cells (inhibitory/excitatory)
e.
Spinal motor neurons:
a. Location: Ventral horn of spinal cord
b. Function: To send motor signal from CNS to skeletal muscle
f.
Satellite cells:
a. Location: Schwann cells in ganglia
b. Function: Structure and metabolism
g.
Schwann cells
a. Location: In the PNS nerve fascicles
b. Function: Myelination of single axons in the PNS and to surround
unmyelinated cells for support
h.
Oligodendroglia:
a. Location: In the CNS; perineuronal are next to a neuron,
interfascicular are chains of cells
b. Function: Myelination of multiple axons in the CNS
i.
Astrocytes:
a. Location: In the CNS; fibrous in white matter, protoplasmic in grey
matter
b. Function: Their processes partially envelope capillaries to help give
blood-brain barrier, provide mechanical support, and mediate
metabolite transport, help repair CNS damage, often undergo mitosis
j.
Ependymal cells:
a. Location: Lining the ventricles and central canal of the spinal cord
b. Function: Give rise to all glial cells, are ciliated epithelial-like cells
without tight junctions
4.
Fine structure and function of:
a.
Dendrites:
a. Structure: Cytoplasmic extensions branching off the soma; tapering
cytoplasm, absence of Golgi and RER
b. Function: To increase the receptive surface of neurons
b.
Dendritic spines:
a. Structure: Small protrusions off of dendrites with bulbous tips
connected to dendrite via a thick neck
b. Function: Site of synaptic contact
c.
Axon hillock:
a. Structure: Initial segment of axon, lacks ribosomes and RER; appears
as a pale triangular zone
b. Function: Lowest threshold for action potentials; region where action
potential decides whether or not to fire
d.
Axon:
a. Structure: Thinnest, consistent processes leaving from soma
b. Function: Propagation of an action potential
e.
Node of Ranvier:
a. Structure: Area of demyelination on the axon
b. Function: Area where action potential slows to regenerate
f.
Nissl body:
a. Structure: Clump of ribosomes visible at the light microscopic level
b. Function: Synthesizes proteins in the neuron
g.
Synaptic vesicles:
a. Structure: 40-60 nm containers in presynaptic bouton containing
neurotransmitters
b. Function: Contain neurotransmitters, chemical basis of transmission
h.
Synaptic boutons:
a. Structure: Small swelling at the termination of an axon
b. Function: Place where synaptic transmission occurs