nervous tissue Flashcards
name the 3 membranes that protect the CNS from deepest to superficial
pia mater, arachnoid membrane, dura mater (PAD)
Epidural anesthetics are injected just outside the _____ mater to numb spinal nerves during certain surgical procedures.
dura
what is the fluid that circulates within the membranes?
cerebrospinal fluid
what neuronal cell bodies contribute to white matter?
axons
what are localized clusters neurons may be found in?
nuclei
what is the main functional unit of the nervous system?
cell body/perikaryon
what is the long process of a neuron that extends from the cell body?
axon
how the axon end in a terminal or and connect with another neuron?
synapse
how can a neuron terminate on a muscle?
motor end plate
what is a smaller processes that arises from the perikaryon?
dendrites
describe the nucleus of a neuron
euchromatic, prominent nucleolus
what are the ribosomes visible as blue granules abundant in the cytoplasm?
Nissl substance
true or false: Dendrites will have cytoplasm with Nissl substance in them, however, the axon will not have Nissl substance
true
what tissue do glial cells form?
c.t. in the nervous system
name and describe the 3 basic types of glia
- Astrocytes- largest with prominent processes. Found close to blood vessels
- Oligodendrocytes-intermediate, ensheath axons. also called neurolemmocytes in the PNS
- Microglia-smallest with extensive processes. Arise from macrophages and therefore serve as immunomodulators
what are aggregations of nerve cell bodies outside the CNS called?
ganglia
where are dorsal root ganglia located?
beside the spinal cord
what are sympathetic ganglia loacted?
outside vertebral column
where are nerves (post ganglionic fibers)?
ganglia from sympathetic and dorsal root ganglia that are long and innervate a variety of tissues and organs
where parasympathetic ganglia located?
close to or within the organs and their postganglionic fibers are very short
what are aggregates of axons within the CNS?
tracts
what are aggregates of axons within the PNS?
nerves
what covers the axons in the PNS?
Schwann cells or neurolemmocytes
what covers the axons in the CNS?
oligodendrocytes
what is the distinction between myelinated and unmyelinated neurons?
one Schwann cell covers multiple axons in unmyelinated nerves, It wraps around a single axon over and over to form a thick covering called the myelin sheath in myelinated nerves
what is the node of ranvier?
junction between 2 Schwann cells on the axon
what are myelinated axons need for?
fast impulse transmission, muscles and joints
what are unmyelinated axons needed for?
slow transmission, salivary glands
how do you distinguish between myelinated and unmyelinated axons in a stain?
- myelinated axons will have neurokeratin around them and have a “candy cane” appearance in cross section
- Unmyelinated axons are wavy and do not have neurokeratin surrounding them
