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36 Cards in this Set
- Front
- Back
What consist of long axons, myelinated and unmyelinated?
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Fibers
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Since the CNS lacks connective tissue, it would be almost formless if it weren't for what?
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Vessels and meninges
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Where is gray matter located? Why is it pinkish-gray in the fresh state?
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In the brain it is covering (cortex) the white matter, and is pink due to an abundent blood supply.
In the spinal cord it is on the interior and shaped like an H or butterfly with the dorsal and ventral horns. |
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What are aggregations of cell bodies embedded in gray matter called?
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Nuclei
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Why is white matter white?
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Due to myelinated axons and glia, appears white due to lipid in myelin sheaths.
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Describe the organization of white matter in the brain and in the spinal cord.
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In the brain the white matter is on the inside and consists of tracts (groups of axons having specific fx). In the spinal cord the white matter is on the outside and arranged as sensory ascending tracts and motor descending tracts. Aggregations of tracts are called columns.
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What are the four major parts of the brain?
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Brainstem (midbrain, pons, medulla oblangata)
Diencephalon (superior to the brain stem) Cerebellum (posterior to brainstem) Cerebrum |
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Outline the meninges, and describe each.
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Dura Mater: outermost layer
Cranial Dura: continuous w/ the periosteum of the skull. Dural reflections or septa. Spinal Dura: Avascular, separated from vertebral periosteum by epidural space which is filled w/ fat & veins Arachnoid: avascular Pia Mater: vascular |
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Neurons in the CNS are all...
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Multipolar
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Excitatory Multipolar neurons communicate via
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neurotransmitter glutamate or acetylcholine
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Inhibitory interneurons are multipolar and release...
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GABA and/or glycine
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What are the four ways neurons are classified?
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Cell processes, cell size, cell fx, and shape or arrangement of processes.
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Interneurons innterconnect other neurons. What are the two types?
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Golgi type I large cell body and long axon
Golgi type II small cell body and short axons |
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When classified by function, what type of neurons are in each:
Sensory Motor Interneurons |
Mainly unipolar, some bipolar
Multipolar Multipolar |
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CNS Nucleus
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Centrally located and contains lipofuscin pigment after age 6 in spinal cord, after age 20 in cerebrocortical neurons
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CNS Processes
Dendrites Axons |
Dendrites have arborization pattern, which increases receptor surface of the neuron
Axons are mostly myelinated |
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Projection Neurons and Local circut neurons
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Golgi type I and Golgi type II respectively
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What are the three functions of neuroglia?
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1. Fx and stxrl support to neurons
2. Establish compartments and monitor passage of materials 3. Participate in defense mechanisms |
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Outline Neuroglia
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A. Macroglia
1. Astrocytes 2. Oligodendrocytes B. Microglia C. Ependyma 1. Ependymocytes 2. Choroidal Cells |
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What are macroglia derived from?
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Neuroectoderm
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Characterize Astrocytes
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Large amt of IF, but few organelles
(white) Fibrous astrocytes have long thin processes and few branches. (gray) Protoplasmic astrocytes (end feet) are found btwn neurons and bld vessels, cover pia, and line ependyma which line ventral of brain |
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Where can GFAP be found?
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Schwann Cells and Astrocytes
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What type of cancer can arrise from glia?
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Glioma - an astrocytoma that is malignant and grows rapidly
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What are the functions of astrocytes? (4)
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Structural - bind pia to capillaries
Astrocyte sheath - cover nodes of Ranvier Regulate K concentration Help form Blood-brain barrier |
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What type of neuroglia in the white matter, has no IF, lots of organelles and is the CNS counter part to SC?
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Oligodendrocytes
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What macrophages of the CNS are derived from mesoderm, and are part of the monocyte lineage?
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Microglia
Fx - phagocytosis |
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Characteristics of ependyma (3)
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No basement membrane
Derived from neuroectoderm Epithelial glial cells |
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Characterize Ependymocytes (4)
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Epi cells that line the ventricles
Gap Jx Striated border microvilli CILIA move CSF |
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Choroid cells
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Make up the secretory epi covering the choriod plexus, where CSF is made.
Have fenestrated capillaries Tight junctions, so CSF can't leak btwn cells, therefore protective Numerous microvilli |
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What should health CSF look like? (constant turnover)
What is the fx of CSF? |
Water, if it is cloudy or bloody something is wrong.
Mechanical protection, cushion. |
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How does nervous tissue react to pressure?
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It dies.
Hydrocephaly |
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Where does reabsorption of CSF into the venous system take place?
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In protrusions called arachnoid villi
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Explain the blood brain barrier
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Tight juntions (**) btwn continuous capillary endothelial cells
It lets in O2, CO2, AA, sugar, but doesn't let in large macromolecules such as albumin or AB |
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Development of central myelin sheath
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From oligodendrocytes, myelinate parts of several axons (tongue-like processes)
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Chemical Structure of Central Myelin
1. MBP 2. PLP (proteolipid protein) |
1. P surface
major dense line 2. E surface intraperiod line |
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What 4 cell types are derived from the mononuclear phagocyte system?
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Osteocytes
APC Macrophages Microglia They are all phagocytes. |