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52 Cards in this Set
- Front
- Back
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Nervous Tissue Histologic Composition
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-Neurons
-Glial Cells -Nerves or Tracts -Nerve Cell bodies -nuclei -ganglia |
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Neurons
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nerve cells and their sometimes extensive processes
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Glial cells
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supportive cells
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an organized collection of nerve cell processes that form a definable anatomical structure is called a
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nerve-peripherally
tract-centrally |
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White matter
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tracts- nervous tissue comprised of nerve cell processes and associated "coverings"
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Grey matter
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- nervous tissue containing an abundance of nerve cell bodies and their immediate projections
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Unipolar
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- single axon that bifurcates
- sensory ganglia located in roots of cranial and spinal nerves |
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Bipolar
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- gives off two processes
- vestibulocochlear afferent neurons; bipolar cells of the retina - convey sensory information to the CNS |
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Multipolar
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- gives off multiple branches, several dendrites, and an axon
- most of the neurons of the CNS, autonomic ganglia of PNS |
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Neurons
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- nerve cells
- highly specialized/modified cells |
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Soma
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neuron cell body
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Components of Nerve Neuron cell
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-Nucleus
-Perikaryon -Golgi complex |
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Perikaryon
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- typically highly granular and basophilic chromatophilic substance - absent from the axon
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Golgi complex
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- secretory cells
- turnover > 30% of their total protein |
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Axon
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cytoplasmic projection which conducts impulses and transport materials away from cell body
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Axolemma
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portion of a cell membrane surrounding the axon of a neuron.
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Axoplasm
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cytoplasm within the axon of a neuron
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Telodendria
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structures at the terminal branches of axon that contain neurotransmitter
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Boutons
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- terminal expansions
- a knoblike enlargement at the end of an axon, where it forms a synapse with other neurons. |
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Dendrites
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- extensions of the nerve cell body
- act to increase its surface area and enhance points of contact with other neurons - bumps or spines represent synaptic contacts |
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Synapse
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highly specialized point of interaction (contact) between neurons or neurons and effector cells where electrochemical transmission occurs
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synaptic vesicles
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neurotransmitter
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presynaptic membrane
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transduces the electrical stimulus into a secretory event
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postsynaptic membrane
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neurotransmitter coupling results in an excitatory or inhibitory event
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Types of Synapses
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- dendrodendritic
- axodendritic - somatosomatic - axosomatic - dendrosomatic - axoaxonotic ( at a Bouton en passage) - |
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Neuroglial (Glial)
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- supportive network of specialized cells ("neural glue")
- nourish & protect the integrity and function of neurons |
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Peripheral glial cells
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- supportive cells of the PNS
- Neurolemmocytes - Schwann cells - Satellite cells (amphicytes) |
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Central glial cells
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- supportive cell of the CNS)
- Astrocytes - Oligodendrocytes - Microglia - Ependymal cells |
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Neurolemmocyte
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Peripheral glial cell
responsible for the formation of myelin MYELINATED axon |
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MYELIN sheath
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- Neurolemma
- concentric rings of "modified plasma membrane“ |
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Neurokeratin
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- filamentous remnants of myelin sheath
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Nerve fiber nodes
(nodes of Ranvier) |
breaks in the continuity between adjacent Schwann cells and myelin.
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Types of Ganglia
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- craniospinal ganglia
- autonomic ganglia |
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Nerve fibers classified as:
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- visceral
- somatic skin, skeletal muscle, joints |
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- visceral nerve fiber
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cardiac, smooth muscle, glands
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somatic nerve fibers are seen:
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– skin, skeletal muscle, joints
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craniospinal ganglia are found:
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- sensory ganglia
- dorsal root ganglia - unipolar nerve |
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autonomic ganglia are found:
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- embedded within the connective tissue associated with smooth muscle cardiac muscle & glands
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Astrocytes
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- Provide structural support
(storing glycogen, glucose) - Component of blood-brain barrier - Phagocytosis |
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Oligodendrocytes
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- Responsible for myelin around nerve fibers
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Microglia
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- transform into macrophages with phagocytic capabilities
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Ependymal cells
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- line brain ventricles and central canal of the spinal cord
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Ependymal cells histological characteristics
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- cuboidal , columnar
- ciliated with microvilli - Lack typical basement membrane |
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Ependymal cells function
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Allows large molecules to pass from CNS extracellular space to cerebrospinal fluid (like lymphatics of the CNS)
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Choroid plexus
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- cuboidal, microlilli
intimate association with pia mater - Fenestrated capillaries - Zonula occludens (ependymal barrier) |
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Meninges
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three layers of investing connective tissue completely surrounding brain, spinal cord, and spinal roots (Dura Mater, Arachnoid and Pia Mater)
- provides a physical and phagocytic barrier contains cerebrospinal fluid (CSF) the nourishes and attenuates shock |
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Dura mater
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- outer most, very tough covering, dense CT
collagen, elastic fibers, and blood vessels |
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Arachnoid
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deep to the dura matter
- consists of a distinct outer membrane, from which radiate outward (from its inner surface) many fine fibrous trabeculae that act as a supportive framework for the subarachnoid space, which contains a filtrate of blood called cerebrospinal fluid |
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Pia Mater
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most intimate protective membrane of the brain and spinal cord
it invests all fissures and depressions Loosely arranged collagen fibers superficially flattened by fibrocytes |
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endoneurium
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- strands of collagenous fibers and CT matrix that occupy space between individual, adjacent nerve fibers
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perineurium
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- CT fibers arranged chiefly longitudinally interposed between bundles of nerve fibers (fascicles)
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epineurium
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- thicker layers of longitudinally arranged collagen and matrix surrounding nerve trunks (around groups of fascicles)
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