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56 Cards in this Set
- Front
- Back
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3 components of the nervous system |
1. central nervous system 2. peripheral nervous system 3. autonomic nervous system |
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central nervous system is composed of |
the brain and spinal cord |
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nerves and ganglia OUTside of the brain and spinal cord |
PNS |
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associatedwith innervation of smooth and cardiac muscle ofviscera2 types |
ANS |
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“fight orflight” responsesnervefibers arise from thoracic and lumbar spinal nerves peripheral ganglia are near the spinal cord postganglionic nerve fibers are long |
sympathetic |
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“rest and digest” responsesnervefibers arise from certain cranial nerves (III, VII, IX, X; so, inbrainstem) and sacral spinal nerves (so,in sacral spinal cord)peripheral ganglia are near the target organpostganglionic nerve fibers are shortall organs of thebody except the liver are innervated |
parasympathetic |
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nerve cell is composed of |
cell body and cell neurites such as dendrites, axons, and ganglion |
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efferent |
motor from the center(cell body or central nervous system) toward a peripheral effector |
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afferent |
sensory from a peripheral receptor toward the center |
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the goal of neurological examination |
Anatomiclocalization of the lesion(s) in the nervous system localization of the lesion(s) influences differentialdiagnosis |
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3 parts of the brain |
forebrain, cerebrum, brainstem |
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gyri and sulci |
ridges valleys |
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grey matter |
Superficial aspects of gyri,forming cerebral cortex contains neurons |
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white matter |
interior aspects of gyri contains primarily axons |
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olfactory bulbs |
at rostroventral aspect of brain |
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brainstem is composed of |
midbrain, pons, medulla Some texts also include thalamus under “brainstem” |
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cerebellum |
centralwhite matter longitudinalmedian ridge = vermis 2 lateral hemispheres |
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spinal cord segmentation |
One spinal cord segment for each vertebra exception: 8 cervical spinal cordsegments a pair of spinal nerves for each spinal cord segment |
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located centrally butterfly-shaped divided into “horns” dorsal horns (receive sensory input) ventral horns (project motor output) intermediate horns (autonomic nervous system) |
grey matter (SC) |
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located peripherally contains myelinated axons divided into “funiculi” dorsal funiculi- sensory, “ascending” tracts lateral funiculi- mixture of sensory and motor tracts ventral funiculi- motor, “descending” tracts |
white matter (SC) |
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major functional divisions of the spinal cord |
C1-C5 (cervical) C6-T2 (cervical “intumescence”)- segments from whichnerves to the thoracic limbs arise T3-L3 (thoracolumbar) L4-S3 (lumbosacral intumescence)- segments to the pelvic limbs, pelvic organs (including urinary bladder), andperineum arise Cd segments (“cauda equina”) |
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spinal nerves |
a. arise as roots from the spinal cord b. a dorsal and a ventral root on each side of the cord c. dorsal roots convey primarily sensory nerve fibers (axons) into the spinal cord d. ventral roots convey motor nervefibers away from the spinal cord |
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innervate striated skeletal muscle |
somatic |
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innervatesmooth muscle (of organs, glands, blood vessels) or cardiac muscle |
autonomic |
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where are the cell bodies of motor fibers located? |
grey matter of the SC a) in ventral horn if somatic fibers b) in intermediate horn if autonomicfibers dorsal and ventral roots fuse nearthe intervertebral space (betweenvertebrae) to form aspinal nerve |
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the spinal nerve is a __________ of sensory and motor components |
mixture |
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Network of ventral branches of spinal nerves C6-T2 which gives rise tovarious specifically named nerves of the thoracic limbs |
brachial plexus |
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Network of ventral branches of spinal nerves L4-L7 and all sacral nerveswhich give rise to specifically named nerves of the pelvic limbs, pelvicviscera, and perineum |
lumbosacral plexus |
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how many pairs of cranial nerves? |
12
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where are the sensory ganglia? |
near, but outside the brainstem |
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where are the motor fibers? |
within the brainstem |
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2 portions of the autonomic nervous system |
a preganglionic portion, from the CNS to a synapse in a ganglion in the PNS a postganglionic portion, from the PNS ganglion to the “target” organ (the site of a second synapse) |
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3 layers of connective tissue protecting the brain |
dura mater, arachnoid mater, pia mater
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dura mater |
one tough mother thick, white, outer fibrous layer |
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arachnoid mater |
cobwebs middle delicate layer thin trabeculae span thesubarachnoid space and connect to the pia mater cerebrospinal fluid (CSF) flows in the subarachnoidspace |
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pia mater |
pie on the inside innermost layer fused to the nervous tissue |
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arachnoid + pia = |
leptomeninges |
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function of ventricular system |
contains and produces cerebrospinalfluid (CSF) |
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Lateral Ventricles |
2!
1) longitudinally oriented inside of each cerebralhemisphere 2) connected to third ventricle by an interventricular foramen (on each side) |
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Third ventricle |
1) dorsoventrally oriented ring, surrounding the“interthalamic adhesion” joining the 2 halves of the thalamus 2) mesencephalic aqueduct comes off its caudal aspect,and connects to the fourth ventricle |
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Fourth ventricle |
ventral to the cerebellum tapers caudally to form the central canal “obex”: the level of the medulla at which the fourth ventricle becomes the spinal canal lateral apertures of the fourth ventricle allow CSF to enter subarachnoid space |
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ependyma |
cells lining the ventricles andthe central canal of the spinal cord |
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choroid plexusepithelium produces... |
CSF |
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CSF is absorbed into blood at the... |
arachnoid villi |
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arachnoid villi |
evaginations of the arachnoid into dural venous sinuses on the convex surfaces of the brain |
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although the brain and spinal cordaccount for only about 2% of the total body weight, the CNS receives about ______%of the total cardiac output of blood because of its high metabolic rate andhigh oxygen demands |
20% |
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membrane potential is determined by 3 things |
1) the concentration of ions across the plasma membrane 2) the actions of membrane pumps 3) the permeabilities of the membrane created by ion channels |
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an action potential is generated when... |
the membrane potential at the axon hillock “depolarizes” enough to reach “threshold” potential |
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3 things that influence the rate of action potentials along the axon |
a. diameter of the axon (faster velocity in larger fibers) b. number (density) of ion channels in the plasma membrane c. whether axons are myelinated or unmyelinated |
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conduction of the action potential by jumping from one node of Ranvier tothe nextmakes action potential conduction much faster |
saltatory conduction |
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Neurons are connected to each other by 2 differenttypes of synapses (name two types) |
chemical and electrical |
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chemical synapses |
1.cNT from vesicles in the axon move across the synaptic cleft btw the pre-and post-syn.mem. 2.the AP stimulates release of thechem NT from the axon terminus 3.the NT binds to receptors on thepost-synaptic membrane, triggering a change in the post-synaptic mem. pot. Most synapses are chemical, including NMJ's |
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electrical synapses |
gap junctions (protein pores) in plasma membranes between 2 cells conductionof membrane potential changes across an electricalsynapse between neurons is faster than across a chemical synapse, but there isno processing of information, and conduction can go ineither direction |
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Excitatory NTs |
-open ion channels to allow extracellularpositively charged ions (e.g., sodium) into thecell by diffusion -less negative membrane potential -glutamate and acetylcholine are excitatoryneurotransmitters 1) both found in CNS 2) Ach is the NT at NMJs |
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Inhibitory NTs |
-open ion channels to allow extracellularnegatively charged ions (e.g., chloride) into thecell by diffusion, or intracellularpositively charged ions (e.g., potassium)to diffuse out -more negative membranepotential -(GABA) is the majorinhibitory NT in the brain, and glycine is the major inhibitoryNT in the SC |
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neurons can beconsidered excitatory or inhibitory because... |
an individual neuron will release only 1 type ofneurotransmitter a recipient neuron can receive input fromboth excitatory and inhibitory neurons |
