Term
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Definition
| Occurs in ampullary region of Fallopian tube 12-24 hours after ovulation |
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Term
| Cell fertalization occurs in how much time? |
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Definition
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Term
| In 40 hours, what occurs? |
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Definition
| 4 cell zygote. A series of mitotic divisions results in rapid increase in the number of cells (blastomeres), which become smaller with each division. |
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Term
| The morula stage involves what and is reached in how many days? |
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Definition
| It is 16 cells and is reached in 3 days. |
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Term
| The blastocyst is what stage and takes how long? |
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Definition
| Called the blastocyst and takes 5 days. The zygote evolves into an inner cell mass and an outer cell mass. The inner cell mass, the embryoblast, gives rise to the tissues of the embryo proper. The outer cell mass forms the trophoblast which later develops into the placenta. |
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Term
| The inner cell mass of the blastocyst is called what and is what? |
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Definition
| The embryoblast and gives rise to the tissues of the embryo proper. |
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Term
| The outer cell mass forms that what and develops into what? |
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Definition
| The trophoblast, which later develops into the placenta. |
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Term
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Definition
| The blastocyst in the uterine wall occurs on day 6. |
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Term
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Definition
Forms the yolk sac and primitive gut and the ectoderm, are formed by the end of the second week.
It is the inner layer; differentiates into the viscera (e.g., digestive system, respiratory system, etc.). |
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Term
| A layer of mesodermal cells is visible between the ectoderm and endoderm during, which week? |
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Definition
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Term
| The nervous system begins to develop from the what? |
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Definition
| The ectoderm once trilaminar embryo has formed. |
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Term
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Definition
| Formation of the neural tube and crest. - At about 16 days of gestation the embryo is in a “trilaminar” state, and the nervous system begins to form from the Ectoderm layer. |
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Term
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Definition
| Neuronal birth and cellular division |
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Term
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Definition
| Movement of neurons to proper region of CNS |
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Term
| Cytodifferentiation and Axonal Elongation |
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Definition
| Maturation of neurons and extension of axonal processes to the appropriate targets |
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Term
| Maturation of Synaptic Contacts and Refinement |
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Definition
| Formation of functional synapses, “pruning” and programmed cell death. |
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Term
| What are the 5 Stages of Nervous System Development? |
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Definition
| Neurulation, Cellular Proliferation, Neuronal Migration, Cytodifferentiation and Axonal Elongation, and Maturation of Synaptic Contacts and Refinement. |
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Term
| What are the layers of the Trilaminar Embryo? |
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Definition
| Endoderm, Mesoderm and Ectoderm |
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Term
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Definition
| middle layer; differentiates into the heart and circulatory system, muscle, bone, and meninges. Also forms somites (embryonic structures that identify adult segmental innervation of skin and muscle) and the notochord (an embryonic structure that develops into the nucleus pulposis of the intervertebral discs). |
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Definition
| outer layer; differentiates into the CNS structures, adrenal medulla and skin. |
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Term
| What is the progressive formation of CNS structures from embryonic ectoderm? |
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Definition
Ectoderm thickens to form neural plate, which develops into several structures listed below. As the structures form, the neural tube separates from overlying ectoderm.
2. neural groove
3. neural folds
4. The neural tube forms a closed tubular structure with a narrow caudal portion (the spinal cord) and a much broader cephalic (rostral) part characterized by dilatations (the brain vesicles; see Table 2, below). The hollow interior of the neural tube forms the ventricles of the brain and the central canal of the spinal cord. The rostral portion (pore) should close by day 27, while the caudal portion (pore) should close by day 30.
5. The neural crest forms sensory ganglia of spinal and cranial nerves and postganglionic neurons of the autonomic nervous system and cells of the adrenal medulla
Once the neural tube has formed, it can be subdivided into distinct sections. These divisions persist from the embryonic to the adult CNS |
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Term
| All of the neural tube, including the caudal portion should be closed by day what? |
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Definition
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Term
| The neural crest forms what? |
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Definition
| The sensory ganglia of spinal and cranial nerves and postganglionic neurons of the autonomic nervous system and cells of the adrenal medulla. |
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Term
| Telencephalon includes the... |
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Definition
| Cerebral hemisphere, basal ganglia, hippocampus (forebrain) |
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Term
| Diencephalon includes the... |
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Definition
| Thalamus, hypothalamus, pineal body, infundibulum (still the forebrain) |
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Term
| Mesencephalon includes the... |
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Definition
| Tectum, tegmentum, crus cerebri (midbrain) |
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Term
| Metencephalon includes the... |
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Definition
| Pons, cerebellum (hindbrain) |
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Term
| Myelencephalon includes the... |
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Definition
| Medulla oblongata (hindbrain) |
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Term
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Definition
| Failure of rostral neuropore to close; much of cerebral hemisphere is absent |
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Term
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Definition
| Failure of the caudal neuropore to close. Vertebrae do not form over the spinal cord, resulting in loss of sensory and motor function at and below the level of the lesion. In all forms of spina bifida there is loss of sensory and motor function at and below the level of the lesion. The lesion is often marked with a tuft of hair and or a pad of fat over the lesion. |
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Term
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Definition
| One or more vertebrae are malformed and covered by a layer of skin. The lesion is often marked with a tuft of hair and or a pad of fat over the lesion. (not as bad) |
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Term
| Spina bifida with meningocele |
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Definition
| Meninges (e.g., dura mater) protrude in a saclike cavity on the back over the defect |
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Term
| Spina bifida with myelomeningocele |
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Definition
| Spinal cord and meninges protrude in a saclike cavity on the back over the defect. (the most severe) |
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Term
| Arnold-Chiari malformation |
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Definition
| Part of cerebellum and caudal brainstem herniate through foramen magnum, obstructing flow of cerebrospinal fluid, and producing hydrocephalus. |
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Term
| The tissue of the neural plate can be divided into three functional layers... |
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Definition
| The Germinal Zone (Ventricular Zone), Intermediate Zone and Marginal Zone (Cortical plate) |
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Term
| The Germinal Zone (Ventricular Zone) |
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Definition
a. Is the innermost layer, consisting of pluripotent neuroepithelial cells that can rapidly divide, eventually forming the cells of the CNS
b. Newly dived cells in the germinal layer can be classified as Neuroblasts and Glioblasts. The neuroblasts then use the glioblasts to help them migrate out of the germinal zone. |
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Term
| Do neuroblasts use the glioblasts to help migrate or the glioblasts use the neuroblasts to migrate? |
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Definition
| The neuroblasts use the glioblasts to help migrate out of the germinal zone. |
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Term
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Definition
Some neuronal precursors (neuroblasts) use fibers from radial glial cells or their own axons to migrate from the Germinal Zone out to the brain's outer layers (Intermediate and Marginal Zones).
Glial fibers radiate from the brain's inner to outer surfaces, serving as a conduit to carry the neurons through the brain to their final destination. The glial cells secrete chemical attractants to help neurons find the correct pathway. Neurons have adhesion molecules on their surface that enable them to bind to glial cell fibers. |
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Term
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Definition
Some neurons migrate in a tangential direction, rather than radial, moving from one radial glia to another, or following axons (can move in to out and over)
Inner layers form first then the outer layers |
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Term
| The sulcus limitans seperates what from what? |
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Definition
| Seperates dorsal from ventral neurons. |
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Term
| The alar plate forms what? |
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Definition
| Dorsal horn, sensory and association neurons. |
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Term
| The basal plate forms what? |
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Definition
| The ventral horn, motor neurons. |
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Term
- Once the neurons reach their final destination, they will differentiate into a specific type of mature neuron (ie. Cortical pyramidal neuron, multipolar alpha motoneuron, cerebellar granual neuron, pseudounipolar dorsal root ganglion neuron).
- The fate of the neuron, depends upon... |
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Definition
| Intrinsic genetic programs, CNS environmental factors, and timing. |
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Term
| is the formation and elongation of an axon part of the maturation process? |
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Definition
It is part of the maturation process.
1. It is not currently know how axons are chosen to be formed, but one theory on axon formation goes as follows:
Initially a neuron sprouts multiple processes termed neurite going in multiple directions. When one reaches a critical distance and is receiving proper signaling cues, it will continue to elongate, while the others will retract and either disappear or become dendrites. |
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Term
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Definition
-enlargement on the distal end of a growing axon, 1st visualized in the 1800’s
-Has finger like extension termed filapodia and lamellipodia
-Using these finger like extensions, the cone will “crawl” along extracellular matrix and other axons towards its target |
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Term
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Definition
-The axon finds its proper target through a complex process involving:
-Contact repulsion-(surface you can’t walk on)
-Chemo repulsion-(think of smells…like garbage…that is not attractive)
-Contact attraction-(surface you can walk on)
-Chemo attraction-(think so smells…good smell…that is attractive)
-These processes usually involve fairly complex receptor and ligand interactions. That is the growth cone of the axon will have receptors on its membrane that will bind to chemicals (ligands, neurotransmitters, growth factors) in the CNS that will either attract it or repulse it. Conversely, the growth cone also expresses proteins on its surface (ligands) that will bind to receptors on the extracellular matrix upon which it is “crawling” that will attract or repel the growth cone. |
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Term
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Definition
| surface that you reject (wall) |
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Term
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Definition
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Term
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Definition
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Term
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Definition
| Smell you are attracted to. |
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Term
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Definition
| Once the target has been reached, as synapse must form. This entails the breakdown of the growth cone, formation of the presynaptic bouton, and the release of neurotransmitters. |
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Term
T or F
The number of neurons and axons produced are just enough and do not allow for mistakes. |
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Definition
| There is more than needed so it is false. The body "fine tunes or prunes" synapses, axons and neurons for optimal function. |
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Term
| 3. The mechanisms thought to underlie the decisions of “who stays or goes” involve... |
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Definition
| activity, neurotrophic factors, and intrinsic genetic programs |
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Term
| Can malfunctions in any one of the aforementioned 5 processes can result in significant disorders or diseases of the nervous system |
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Definition
| Yes, malfunctions result in significant disorders and diseases. |
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Term
| Manifestation of Deranged Nervous System in the Neonate can result in... |
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Definition
1.Impairments of alertness and arousal
2.Disturbances of eye movement (oscillations, nystagmus, loss of conjugate eye movement with vestibular stimulation)
3.Failure to feed
4.Motor complications (hypotonia, tremors, clonic jerking, tonic spasms, diminished limb movements, and opisthotonos--extreme hyperextension of neck, trunk and LEs)
5.Irregular breathing
6.Hypothermia or poikilothermia
7.Seizures
8.Cardiovascular abnormalities (e.g., bradycardia, circulatory difficulties, poor color) |
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Term
T or F
Neurons or somas in the CNS are USUALLY replaced? |
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Definition
| They are not replaced, so false. This death is long lasting and permanent. |
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Term
| Is damage to the CNS axons permanent or can they be regenerated? |
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Definition
| It is permenant and do not regenerate in the CNS. |
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Term
| Can PNS axons be regenerated if injured or is it permenent? |
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Definition
| May be temporary, as axonal regeneration can and does frequently occur. |
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Term
| If an axon is hurt or destroyed, does this cause the axon to die? |
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Definition
| Injuries to the axon, however do not invariably lead to neuronal death. Under some circumstances, neurons are capable of regenerating their axonal projections and re-establishing contact with other cells, and considerable function can be restored. Damage to peripheral motor and sensory axons (i.e., peripheral nerve injury, PNI) may occur due to contusion, crush injury, or complete transection (axotomy). |
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Term
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Definition
loss of blood and oxygen
A.The loss of blood deprives the cell of much needed oxygen and glucose.
B.This in turn depletes the cell of its energy stores (ATP) and causes the disruption of membrane transport systems, specifically the ability to reuptake glutamate into the cell.
C.This creates increased extracellular concentrations of glutamate.
D.The increased concentration of extracellular glutamate hyperexcites the compromised cells causing:
i.increased influx of calcium
ii.increased release of glutamate.
E.The increased intracellular calcium sets off a cascade of destructive enzymes that damage the integrity of the cell.
F.The release of glutatmate from the damaged/dead cell hyperexcites neighboring cells.
G.The cells will die in a process termed excititotoxic cell death. |
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Term
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Definition
Direct trauma to the cell, i.e. TBI and SCI
A.Trauma physically disrupts the neurons (epicenter of an injury)
B.Trauma disrupts blood flow and causes ischemic cell death (described above)
C.Trauma causes swelling that will cause compression in CNS cutting off blood supply (leading to ischemia) and physically crushing neurons)
D.Trauma and acute cell death can lead to the release of many factors (such as free radicals and caspases) that can trigger apoptotic cell death. |
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Term
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Definition
Programmed or deliberate cell death.
A.The "decision" for apoptosis can come from the cell itself (intrinsic inducers) or from its surrounding cells and tissue (extrinsic inducers).
B.This is normal during development, but abnormal in the adult CNS
C.Both extrinsic and intrinsic pathways have in common the activation of central effectors of apoptosis, caspases, which carry out the cleaving of both structural and functional elements of the cell, resulting in the charateristic morphological changes.
D.Apoptotic cells undergo a well characterized sereis of morpholigical changes prior to death including: rounding, chromatin breakdown, chromatin condensation, membrane blebbing, formation of apoptotic bodies. |
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Term
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Definition
| Paralysis and anesthesia of varying duration, depending on extent of injury; possible autonomic disturbances. |
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Term
| Neuropraxia is what degree of injury? |
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Definition
| Lowest degree of injury, axon remains intact, but signaling is disrupted |
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Term
| Axonotmesis is what degree of injury? |
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Definition
| Axon is disrupted but the neural sheath is intact |
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Term
| Neurotmesis is what degree of injury? |
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Definition
| Both Axon and its surrounding sheath is disrupted |
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
| unorganized bulbous mass of nerve axons and Schwann cells; often quite painfull |
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Term
| What happens when the CNS has an axonal injury? |
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Definition
1.CNS myelin is formed by oligodentrodrocytes, not Scwhann cells.
- Oligodendorcytes secrete proteins such as (Nogo) that are inhibitory to axonal sprouting and regeneration
2.The intrinsic upregulation of growth and regeneration associated genes and proteins by the injured cell is transient and truncated.
3.Astrocytes can become “reactive” and form a glial scar
4.Axonal regeneration is unsuccessful in the CNS |
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Term
| Neuroplasticity can be defined as |
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Definition
the ability of neurons to:
1.Change their function, and/or
2.Change their chemical profile (amount and types of neurotransmitters and/or receptors), and/or
3.Change their structure (number and size of dendrites, soma size, axonal sprouting, and axonal regeneration) |
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Term
| At the synapse, plasticity can take the following forms: |
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Definition
1. Increased/Decreased number of synaptic vesicles in the presynaptic terminal.
a. This will result in increased/decreased release of neurotransmitter in response to a single action potential, thereby possible increasing/decreasing the effects of that action potential.
2. Increased/Decreased number/density of postsynaptic membrane receptors
a. This will increase or decrease the response of the postsynaptic neuron to neurotransmitter release.
3. A change in the type of postsynaptic membrane receptor
a. This will alter the postsynaptic neuronal responses to neurotransmitter release
4. Formation of novel synapses on the same cell (normally associate with dendritic spine changes)
a. Depending upon the type of receptors at these novel syapses, it could increase or alter the effects of a neurotransmitter on the postsynaptic neuron
5. Pruning of established synapses
a. Will decrease or eliminate the connection between the two neurons |
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Term
| In the axon, Neuroplasticity normally takes one of two forms: |
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Definition
1. Regnerative sprouting (regeneration)
a. The proximal end of severed axons may reform a growth cone and restart the process of axon elongation. In practice, this occurs in the PNS only
2. Collateral Sprouting
a. An intact axon will sprout a collateral branch to synapse on neurons it did not previously synapse on. Can occur in the CNS |
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Term
| In the Soma, Neuroplasticity normally takes to form of: |
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Definition
1.Altered gene expression
a. This may lead to altered protein synthesis
b. Alterations in cell health or function. |
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Term
| Hebb’s Law or The Hebbian Learing Rule |
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Definition
Cells that fire together, wire together.
means that the synapse of two neurons is strengthened when their temporal activation is concurrent. When we use it over and over again. |
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