Nervous System Flashcards
cells of nervous tissue
Neuron
Neuroglial cells / Neuroglia / Glial Cells / Gliocytes
DEVELOPMENT OF NERVOUS TISSUE
ectoderm
CNS: brain and spinal cord
PNS: cranial, spinal,
peripheral nerves
Neuron 3 main parts
Cell body
Dendrites
Axon
what do you call the cell membrane of the neuronner
neurolemma
Main part from which axon & dendrites arise. it is also called perikaryon or soma.
cell body
clumps of basophilic
substance (aggregates of RER and free
polyribosomes)
Nissl bodies
nissl substance is present in axon hillock and axon
false
pale staining area of cell body
Axon hillock
▪ Relatively long, cylindrical process
▪ Arises from axon hillock & ends on effector organ or ganglia
Axon
Axon Gives off terminal branches called ____ with expanded _____ ______ ______
telodendron
terminal synaptic bulb
plasma membrane of axon?
what do you call the cytoplasm of axon?
axolemma
axoplasm
what are the processes of neurons?
axon
dendrites
also called nerve fiber
axon
2 types of axon
unmyelinated
myelinated
Surrounded by Schwann cells/oligodendrocytes wrapped
several times forming a _____
myelin sheath
Lipid-rich, insulating sheath
Extends from the initial segments of the axon to the
terminal branches
myelin sheath
Gaps in myelin sheath between the myelinating cells
Myelin sheath is absent
nodes of ranvier
▪ Typically short, small processes radiating from the cell body
▪ May branch and re-branch with each branch tapering at its end
▪ All organelles are present
dendrites
Small dendritic branches have tiny projections called _____
dendritic spine/gemmules
CLASSIFICATION OF NERUONS (4)
unipolar
bipolar
multipolar
pseudounipolar
One cell body, one axon
Found in sensory ganglia located in roots of cranial and spinal nerves
unipolar
One dendrite and one axon; purely sensory
Sensory neurons of the retina, the olfactory epithelium, the inner
bipolar
Cell body gives rise to multiple branches, several dendrites, and an
axon
Most common
multipolar
CLASSIFICATION OF NEURONS BASED ON FUNCTION (3)
sensory neurons
interneurons
motoneurons
Afferent
Receive stimuli from receptor
Sensory neurons
Act as connectors between neurons in a chain or typically between sensory and motor
neurons within the CNS
Interneurons
Efferent
Send impulses from the CNS to the targets organs (e.g. muscles, glands)
Motoneurons
4 TYPES OF NEUROGLIAL CELLS IN CNS
- Oligodendrocytes
- Astrocytes
- Ependymal cells
- Microglial cells / microgliocytes
Smaller than astrocytes with fewer
cytoplasmic processes
Predominant glial cells in _____
A single oligodendrocyte can surround and
myelinate several axons
oligodendrocytes
white mater
Functions:
Myelinates and insulates CNS axons
Allows faster action potential propagation
along axons in the CNS
oligodendrocytes
Most numerous glial cells of the brain
Most abundant glial cells in _____ matter
Most diverse structurally and functionally
astrocytes
gray matter
Functions:
Provide structural support to CNS
Helps form the blood-brain barrier
Regulates interstitial fluid composition
Assists with neuronal development
Replicates to occupy space of dying neurons
Astrocytes
2 types of Astrocytes
Fibrous astrocytes
Protoplasmic astrocytes
type of astrocyte With long, slender, and moderately branched processes
Abundant in white matter
Fibrous astrocytes
type of astrocyte With many shorter and highly branched processes
Abundant in gray matter
Protoplasmic astrocytes
Simple cuboidal or low columnar epithelial cells
In some locations of the CNS, apical surface contain cilia
and microvilli
Ependymal cells
Functions:
Lines ventricles of brain and central canal of spinal cord
Assists in production and circulation of cerebrospinal fluid
(CSF)
Ependymal cells
Smallest glial cells
With actively mobile processes evenly distributed
throughout gray and white matter
Microglial cells / microgliocytes
Functions:
Phagocytic cells that move through the CNS
Constitute the major mechanism of immune
defense in the CNS
Protects the CNS by engulfing infectious agents and other potential harmful substances
Microglial cells / microgliocytes
2 TYPES OF NEUROGLIAL CELLS IN PNS
Amphicytes
Schwann cells (aka Neurolemmocytes)
Derived from the embryonic neural crest
Surround the neurons of PNS ganglia
Satellite glial cells (aka Amphicytes)
Functions:
Electrically insulates PNS cell bodies
Regulates nutrient and waste exchange for
cell bodies in ganglia
Satellite glial cells (aka Amphicytes)