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mcb 163 lec3
spinal cord organization
| Question | Answer |
|---|---|
| apoptosis | the process of programmed cell death (PCD); factor in spinal cord injury |
| factors in spinal cord injury | blood flow changes, BBB broken, free radicals, apoptosis |
| ventral horn/column | motor |
| dorsal horn/column | sensation |
| horns | gray matter |
| columns | white matter |
| dorsal root+ventral root= | spinal nerve |
| Dorsal horn | first common pathway for sensation (pain, temp, touch); integrative role in descending control of pain |
| Ventral horn | origin of motor outflow |
| Alpha motorneurons | innervate extrafusal muscle. |
| Gamma motoneurons | intrafusal |
| Interneuronsin ventral horn | coordinate discharge of motorneurons |
| Renshaw cells | Recurrent inhibition; under descending control of cerebral cortex and propiospinal influences. |
| renshaw cells | glycine release; negative feedback |
| C. tetani | rod shaped anaerobic bacterium; Inhibits release of glycine |
| tetanospasm | cleaves synaptic vesicla components |
| hyperreflexia | over-active reflexes; indicative of upper motor neuron disease as well as the lessening or loss of control ordinarily exerted by higher brain centers of lower neural pathways (disinhibition). |
| dorsal horn | sensory role for pain and temperature; integrative role for pain in descending (brain to spinal cord) control of pain |
| dorsal horn | first common pathway for sensation |
| ventral (anterior) horn | origin of motor outflow |
| alpha motoneurons | innervate extrafusal muscle fibers and develop much force |
| gamma motoneurons | innervate intrafusal muscle and regulate the excitability of muscle receptors |
| spinal interneurons | mediate intraspinal interactions that coordinate motoneuron discharge |
| intermediolateral cell column | the spinal basis for thoracicolumbar autonomic control |
| autonomic motoneurons | project to ganglia where neurons innervate smooth muscle |
| spinal afferent axons group A | myelinated, thickes fibersrepresent large ganglion cell axons innervating rapidly adapting corpuscular mechanoreceptors |
| pinprick-like pain | intermediate-sized group A spinal afferent axons |
| A delta fibers, or Aδ fibers | associated with cold and pressure, and as nociceptors they convey fast pain information |
| C fibers | are a type of axon that classifies its attached free nerve endings, which are pain-sensing nociceptors. |
| unlike other nerves in the NS, c fibers are not | myelinated, this makes them slow conducting |
| Capsaicin (like chili peppers!)activates | C fibers |
| dorsal roots | effects of lesions include anesthesia |
| ventral roots | effects of lesions include paralysis and loss of autonomic control |
| Renshaw cells are | key players in the intrinsic modulation of motoneurons |
| Renshaw cells | provide recurrent inhibition onto a motoneuron, thus runaway excitation is checked |
| Renshaw cell-mediated inhibition of Ia inhibitory interneurons results | in a disinhibition of neighboring motoneurons |
| Renshaw cells are under _______ control of the cerebral cortex and propriospinal influences as well; these are properties shared with all other spinal neurons | descending |
| plexus | area where nerves branch and rejoin |
| sympathetic (thoracicolumbar) chain ganglia | promotes visceral output for digestion and urine production |
| parasympathetic (craniosacral) ganglia | essential for voluntary control of micturition, ejaculation, and milk ejection |
| dermatomes provide a | segmental map of the body surface that is conserved in the brain |
| innervation density is proportional to | sensitivity or fineness of movement |
| the neuromuscular spindle | is a receptor embedded in the muscle that signals length |
| Ia afferent system conveys | information to (i) the brain and (ii) the spinal cord |
| the only route to for entry into the CNS is through the | dorsal root ganglion |
| dorsal horn serves as a highway | for entering ganglioncell fibers, but receives no touch related synaptic endings |
| precision of motor control is ensured by | intercalated spinal interneuron and reciprocal inhibition |
| the sole source for motor output to reach muscle | are the ventral horn motoneurons |
| alpha motoneurons | are the force-developing, fast-firing cells that innervate skeletal muscle |
| motor end plate | is the synaptic ending that depolarizes the muscle cell, causing it to contract |
| adequate stimulus | is the strength of a sensory cue required to elicit a motor output |
| threshold | is the level of sensitivity at which the cell discharges 50% of the time |
| reciprocal facilitation of ipsilateral synergist motoneurons | the adaptive significance of reciprocal inhibition and facilitation |
| positive signs such as spasticity indicate | release from normal inhibition, consequent hyperreflexia and increased muscle tonus |
| negative signs such as muscle weakness indicate | pathological absence of normal facilitation, consequent hyporeflexia and decreased muscle tonus |
Created by:
greerbaby
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