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51 Cards in this Set
- Front
- Back
The reticular formation occupies the central core of the brainstem known as what?
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the tegmentum in the pons and midbrain
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Lesions of the reticular formation, especially of upper brain stem levels can cause what?
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devastating neurological defecits such as loss of consciousness, and gaze paralysis
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What are some of the sensory inputs to ARAS?
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spinothalamic, trigeminal and acoustic systems
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Does the dorsal column system contribute inputs appreciably to the ARAS?
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NO
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What feature of the neurons of the ARAS makes them well designed to receive multiple inputs from different sources?
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long radiating dendrites
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Where do the outgoing fibers from ARAS ascend in ?
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central tegmental tract
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Where do the ascending fibers go to from ARAS?
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Intralaminar thalamic nuclei
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Intralaminar thalamic nuclei have localized or diffuse projections to cortical areas?
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Diffuse projections to widespread cortical areas
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Is strong stimulation from intact sensory pathways alone enough to reverse the unconscious state?
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No, you need ARAS activity to maintain consciousness
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This system maintains consciousness, arouses someone from sleep, mediates cortical activity during REM, and makes cortical neurons more excitable to ascending systems?
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Ascending Reticular Activating System
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What is the location of the descending medial pathway for pain modulation?
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next to the midline fo the medulla
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What kinds of cells are in the descending medial pathway for pain modulation?
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Large serotonergic neurons
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What are some of the inputs to the descending medial pathway for pain modulation?
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pain suppresion systems such as the midbrain periaquaductal gray
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Where do outputs from the descending medial pathwway for pain modulation go to ?
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bilaterally to lamina 1 and 2 to suppress pain
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This system is responsible in producing analgesia in response to fight or flight?
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Descending Medial Pathway for Pain modulation
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The pontine reticulospinal tract arises from the giant nuclie of cells located where?
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medial reticular zone of pons and rostral medulla
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Th medullar reticulospinal tract originates from giant nuclei found where?
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medial reticular zone of the mid-medulla
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Which reticulospinal motor pathway descends uncrossed in the MLF to all spinal levels?
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pontine reticulospinal tract
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Which reticulospinal motor pathway descends bilaterally via the ventrolateral funiculus to all spinal levels?
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medullary reticulospinal tract
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Which reticulospinal motor pathway facilitates muscle tone and mediates phasic motor activity particularly for axial and proximal limb muscles?
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PRST
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Which reticulospinal motor pathway is inhibitory and plays a rol in the atonia seen during REM sleep?
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MRST
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Various catecholaminergic cell groups throughout the intermediate region of the medullary and pontine reticular formation perform what function?
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control blood pressure and heart rate (autonomic control)
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Where do projections from the catecholaminergic cell groups project to?
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thoracic IML (sympathetic preganglionic cell column) and rostrally to the hypothalamus
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The ventrolateral catecholaminergic cell group plays a particularly important role in what?
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blood pressure
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What is the location of cells that are involved in serotonergic pathways?
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raphe nuclei (midline of the brain stem)
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What do the ascending serotonergic neurons function in?
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"gating" or suppressing sleep mechanisms
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Serotonergic neurons that innervate blood vessels cause dilation or constriction?
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vasoconstriction
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agents that block serotonin neurotransmission are used in the treatment of what?
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migraines
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What monoaminergic transmitter is made within cells located in the tegmentum of the upper pons just lateral to the periaqueductal gray within the locus ceruleus?
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noradrenaline
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Norepinephrine (noradrenaline) is released throughout the CNS in situations that require what?
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vigilance and focused attention
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Neurons that synthesize dopamine can be found where?
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substantia nigra, pars compacta, and ventral tegmental region (ventral to red nucleus)
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Degeneration of dopamine-containing neurons in the pars compacta can lead to what
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Parkinsons
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An overriding dominance of dopaminergic activity due to loss of other functions in the forebrain, can be seen in patients with?
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schizophrenia
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This small cell group lateral to the mammilary bodies houses histamine synthesizing neurons?
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tuberomammillary nucleus
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What does the histaminergic pathway in the CNS function as?
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stimulating arousal during wakefulness, and functions in sleep-wake cycle
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Inability to remember moments just before the injury is called what?
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retrograde amnesia
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Inability to remember events after the injury is called?
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Anterograde amnesia
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What is the immediate biomechanical effect that can cause concussion?
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rotation of the neuraxis at flexure of brainstem with diencephalon
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What does the release of glutamate do that causes some of the symptoms of concussion?
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increases metabolic demand and reduces O2 levels
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Decreased cerebral metabolsim of what can persist for days to months after the injury?
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glucose
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What are the two main CNS structures involved with coma and other altered states of consciousness?
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diffuse cortical damage; damage to brainstem at upper pontine or midbrain levels
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Consciousness involves the coordinated action of what three things?
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cerebral cortex, thalamus, and ARAS
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Does cortical or thalamic damage need to be extensive in order to alter the state of consciousness?
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Yes, should be a mass lesion or herniation
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Damage to a small region is worse in the cortex or upper brainstem in terms of altering the state of consciosness?
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upper brainstem
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The largest subgroup of patients presentign with altered states of consciousness have what kind of impairment?
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metabolic interuption of neuronal activity (subcellular processes are disrupted)
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What are the "big three" causes of altered states of consciousness?
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intoxication, stroke, cranial trauma
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What are the three main states of altered consciousness?
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Coma, vegetative, minimally conscious
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A patient who is unresponsive and does not open eyes to stimulation exhibits what state of consciousnes?
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coma
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a patient who is unresponsive but opens eyes and expresses random reflexes and emotions is in what state of consciousness?
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vegetative
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A patient who is awake, alert, and communicative but can only open eyes and move eyelids is suffereing from what?
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Locked in syndrome
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Variable or inconsistent state of awareness, communication, and movement on commands is found in what state of consciosness?
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Minimally-conscious state
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