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64 Cards in this Set
- Front
- Back
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main functions of nervous system
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-monitors changes occurring both inside and outside the body
-processes and interprets input (integration) -dictates a response by activating effector organs |
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CNS
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Brain and Spinal Cord
-incoming stimuli is integrated, correlated -thoughts, emotions generated -most nerve impulses that stimulate muscles and glands to secrete are generated |
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PNS
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Cranial & Spinal Nerves
-Input: Sensory or Afferent neurons (carry impulses to CNS) -Output: Motor or Efferent neurons (carry impulses to muscles and glands) |
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nervous system development
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fertilized ovum --> blastocyst
Inner cell mass flattens to become an embryonic disk embryonic disk flattens to form 3 layers (ectoderm -> mesoderm and endoderm) at 3 weeks, ectoderm form neural plate |
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neural plate
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comes from ectoderm at 3 weeks
source of the majority of neurons and glia groove forms in the neural plate to give you a hollow tube called the neural tube |
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what does mesoderm form?
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notochord and somites (muscle and bone)
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formation of neural tube
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(at 3 weeks) ectoderm --> neural plate --> neural tube (spinal cord and brain)
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neural tube closure
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neural crest cells break off bilaterally when neural tube closes
anterior and posterior openings in Neural Tube closing starts in the middle and proceeds to the ends eventually closing the Neuropores |
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neural tube defects
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neural tube closes by 1 month of gestation
folate is required for neural tube closure |
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neural tube anterior pore
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brain
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neural tube posterior pore
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spinal cord
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anencephaly
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failure of anterior neuropore to close causes anecephaly
lack of brain formation fatal |
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spina bifida
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failure of posterior neuropore (spinal cord) to close
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prosencephalon
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forebrain
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mesencephalon
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midbrain
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rhombencephalon
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hindbrain
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medulla
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(brainstem)
continguous with spinal cord respiration and heart rate |
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pons
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(brainstem)
relay between cerebrum and cerebellum |
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midbrain
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(brainstem)
relay between cerebrum and spinal cord |
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thalamus
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sits on top of brainstem
integration of sensory input before proceeding into the hemispheres |
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hypothalamus
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controls the visceral nervous system
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CSF
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formed by choroid plexuses of lateral ventricle, third, fourth ventricle
CSF flows into 3rd ventricle, continues into cerebral aqueduct and 4th ventricle and central canal of the spinal cord CSF production is continuous and without any feedback mechanism |
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function of CSF
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1. shock absorber for the brain
2. deliver nutrients and remove wastes 3. flows between brain and spine and compensates for changes in inter cranial blood volume |
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hydrocephalus
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obstruction to flow in enlarged ventricles
excess fluid in ventricles- get expansion of head can be caused by meningitis, tumors, inflammation, trauma infants: not bad, shunt to abdomen in adults its really bad! leads to brain compression! |
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causes of hydrocephalus
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meningitus, tumors, inflammation, trauma
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meninges
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surround nervous system
dura mater -> tough mother (outer) arachnoid -> spider web pia mater -> lies right against neural tissue CSF is in subarachnoid space (between arachnoid and pia mater) |
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lumbar puncture to remove CSF
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lumbar region is ideal site to access subarachnoid space because the spinal cord terminates at L2/L3. The subarachnoid space extend further, therefore there is a large CSF-filled space containing lumbar and sacral nerve roots, but no spinal cord
insert needle below conus medullaris |
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multipolar neuron
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1 axon, many dendrites
unidirectional brain & spinal cord impulse travels from the dendrites to the cell body, continuing to the axon in one direction |
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bipolar neuron
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2 arms; specialized sensory neurons
retina, inner ear, olfactory area of brain one branch conducts towards the cell body and the other away |
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unipolar neuron
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always sensory
1 direction brings info from periphery into CNS have a single short process attaching cell body to the axons (cell body is separated from axon) |
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sensory neurons are ____ neurons
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unipolar
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motor neurons are _____ neurons
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multipolar
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interneurons
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multipolar neurons
in CNS; connect afferent (sensory) neurons and efferent (motor) neurons in neural pathways |
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what are the support cells of the CNS
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(glia)
1. Astrocytes 2. Microglial Cells 3. Ependymal Cells 4. Oligodendrocytes |
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astrocytes
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support cells of the CNS
"glue"- support, neuronal health, blood brain barrier |
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microglial cells
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support cells of the CNS
surveillance and immune like functions |
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ependymal cells
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support cells of the CNS
line the ventricles; CSF circulation and production |
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oligodendrocytes
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support cells of the CNS
myelin production |
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what are the support cells of the PNS
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Schwann Cells (forming myelin sheath)
Satellite Cells (have astrocyte and microglial like functions) |
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neuron
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cell that processes and transmits info in the nervous system
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nerve fiber
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consists of an axon that is surrounded by a connective tissue called the endoneurium
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endoneurium
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connective tissue that covers a single nerve fiber
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nerve fascicle
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a bundle of multiple nerve fibers enclosed by a connective tissue layer called the perineurium
nerve fascicles can be comprised of a mix of sensory and motor nerve fibers |
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perineurium
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connective tissue that covers a nerve fascicle
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nerve
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a bundle of nerve fascicles enclosed by a connective tissue layer called the epineurium
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epineurium
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connective tissue that covers nerves
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spinal nerves
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(PNS)
31 pairs arise from the spinal cord sensory/motor |
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cranial nerves
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(PNS)
12 pairs (all but the first arise from the brain stem) largely concerned with the head |
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visceral nervous system
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("autonomic nervous system")
motor and sensory innervations of cardiac muscle, smooth muscle, glands, sensory innervations of viscera locations- components in brain, spinal cord, cranial, and spinal nerves (both CNS and PNS) |
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viscera
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organs of the thoracic, abdominal, and pelvic cavities, blood vessels, sweat glands, hair rising muscles
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spinal nerve
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dorsal root + ventral root
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all sensory axons leave spinal cord on the _____ side
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Posterior (dorsal) side
(sensory input- afferent) |
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all motor axons leave spinal cord on the ____ side
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Anterior (ventral) side
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dorsal root ganglieon
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located on dorsal root
contains cell bodies for all the sensory neurons |
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how many spinal nerves do humans have?
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31 pairs
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where does spinal cord end?
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around L2/L3
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what are the spinal nerve pairs?
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Cervical: C1-C8
Thoracic: T1-T12 Lumbar: L1-L5 Sacral: S1-S5 Coccyx: Co |
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where do we get spinal nerve enlargements? why?
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cervical enlargement- forearms
lumbar enlargement- legs due to increased innervations |
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where does spinal cord start and end?
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extends from Foramen Magnum to the level of vertebra L1, L2
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what is the posterior horn of the spinal cord?
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grey matter
receives sensory info from dorsal root ganglion |
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what is a reflex arc?
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tracts that travel through the spinal cord which sense a stimulus and initiate a response without waiting for input from the brain
consist of a sensory neuron, a motor neuron, and sometimes an interneuron |
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monosynaptic reflex arcs
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sensory neuron synapses directly on a motor neuron
2 neurons bypasses brain (no memory) |
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polysynaptic reflex arcs
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input synapses to interneuron, which then synapses on the motor neuron
the interneuron can send info up to the brain (memory formation) |
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rami
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first branch off of peripheral nerves
after exiting spinal cord, the spinal nerve branches into the Posterior Ramus and the Anterior Ramus |
