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104 Cards in this Set
- Front
- Back
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List the different patterns of communication in the nervous system:
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point to point
neurosecretory hormones autonomic (ANS) diffuse modulatory systems |
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what is point to point communication?
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synaptic activation of target cells restriced to cleft at synapse; NT released with each impulse; postsynaptic actions breif lasting only as long as NT is in cleft; NT broken down or taken back into cell
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explain neurosecretory communication:
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the secretory hypothalamus releases hormones directly into the blood stream slowly affecting many targets throughout the brain and body
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what is autonomic communication?
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networks of interconnected neurons of the ANS working to control responses in glands, vessels and organs
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explain diffuse modulatory communication:
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exists entirely in the CNS
consists of several related cell groups that use different NTs have highly divergent axonal projections and prolong their actions by using metabotropic postsynaptic receptors regulate arousal and mood |
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What is Homeostasis?
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maintenance of the body's internal environment within a narrow physiological range
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what are the 3 functional zones of the hypothalamus? and what are their functions?
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lateral= output to control regulation and motivation of feeding behavior
medial= integration and establishing set points perioventricular= receptive zone, sensory, synchronizes circadian rhythms with light/dark cycles, control of ANS |
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what can be caused by a defect in the dorsal thalamus?
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a discrete sensory or motor deficit: a little blind spot or lack of feeling on a portion of the skin
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What can be caused by damage to hypothalamus?
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can produce dramatic and often fatal disruptions of widely dispersed body functions
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what does suprachiasmatic nucleus (SCN) do? and where is it located?
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recieves direct retinal innervation and function to synchronize circadian rythms
in periventricular hypothalamus along with neurosecretory neurons |
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how does the hypothalamus control and connect with the pituitary?
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magnocellular neurosecretory cells extend axon around optic chiasm down stalk and into posterior pituitary and release neurohormones
parocellular neurosecretory cells communicate with anterior pituitary via the bloodstream with hypophysiotropic hormones |
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What neurohormones are released by magnocellular neurosecretory cells?
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oxytocin and vasopression/ADH
into the posterior pituitary |
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what does oxytocin do?
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causes uterus to contract
stimulates lactation by letdown reflex which can be stimulated by somatic sensations generated by baby |
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what does ADH/vasopressin do?
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regulates blood volume and salt concentration
decreased volume/increased salt will cause drinking behavior |
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How does ADH control water balance/ what happens when pressure is low?
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lowered blood pressure causes kidney to secrete renin into blood, which causes Angiotensinogen release from liver which is converted by renin to Angiotensin I and then A II
Angiotension II causes kidneys and blood vessels to increase pressure and casues subfornical organ to activate ADH release and produce thirst ADH will cause water retention and reduced urine production |
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how does the anterior pituitary differ from the posterior?
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anterior pituitary is a gland, controlled by the hypothalamus
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Describe control in the anterior lobe of the pituitary:
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parvocellular neurosecretory cells secrete hypophysiotropic hormones into a capillary bed at the floor of the 3rd ventricle
these blood vessels run down pituitary stalk and into anterior lobe- hormones communicate via the bloodstream and bind to pituitary cell receptors |
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explain the letdown reflex
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reflex to lactate in mothers with newborns
sensory stimulus (visual, somatic,or auditory) reaches cerebral cortex via the thalamus and stimulates the hypothalamus to trigger oxytocin release and lactation |
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explain stress response by adrenal glands:
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under stress, parocellular neurosecretory cells in periventricular haypothalamus secrete CRH into blood -> this travels to anterior pituitary and stimulates the release of ACTH -> this travels to adrenal cortex and stimulates release of cortisol-> this mobilizes energy reserves and suppresses the immune system to face stress
cortisol can cross blood brain barier and bind to receptors that will in turn inhibit CRH |
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describe the branches of the autonomic nervous system:
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sympathetic- fight of flight
causes in/HR, in/BP, de/digestion, and mobilized glucose reserves for energy parasympathetic- rest and digest de/HR, de/BP, in/digestion |
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describe properties of the ANS as compared with the somatic nervous system
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actions are multiple, widespread, and relatively slow
commands all tissue and organs except skeletal muscle outside the CNS disynaptic pathway |
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describe the disynaptic pathway of sympathetic and parasympatetic ANS:
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preganglionic neurons from CNS drive postganglionic neurons that act on organs
sympathetic: pre uses ACh, post uses NE (emerge from thoraic and lumbar areas) parasympathetic: pre and post use ACh (emerge from brain stem and sacral areas) |
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Where is the enteric system located and what does it control?
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located in lining of esophagus, stomach, intestine, pancreas, and gall bladder
controls transport and digestion of food |
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what is the enteric system called and what are the two parts of it?
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little brain
myenteric (Auerbach's) plexus submucous (Meissner's) plexus |
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what does a polygraph do?
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its a lie detector
it detects sympathetic reactions of the ANS |
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Submucous (Meissner) plexus:
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deeper b/t circular muscle and inner dermal layers
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Myenteric (Auerbach's) plexus
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outer control smooth muscle, creates waves of activity to move food
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which connections are essential to autonomic control?
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periventricular zone connections to the brain stem and spinal cord
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what does the nucleus of the solitary tract do?
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it is located in medulla and connected to the hypothalamus
integrates sensory info from internal organs and coordinates output to autonomic brain stem nuclei |
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what NT are used in preganglionic neurons?
how does it act? |
ACh in both sympathetic and parasympathetic
ACh binds to nAChR--> EPSP and binds mAChR -> (metabotropic G protein) slow EPSP and IPSP can also use neuroactive peptides that interact w/ G protein and make small EPSP (modulatory) |
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describe postganglionic neurons and how they act:
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parasympathetic- use ACh & have local affects on targets w/ mAChR
sympathetic- use NE for far reaching effects |
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What do sympathomimetric NTs do?
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they promote NE and inhibit mACH
ex. Atropine (antagonist for mAChRs, dialates pupils) |
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what do parasympathomimetric NT's do?
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promote mACh and inhibit NE
ex. propranolol- antagonist for beta receptor for NE- slows HR and lowers BP |
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what are the common principles of diffuse modulatory systems?
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- core small set of neurons
-neurons arise from the central core of brain -each nueron can influence many others b/c axon contacts postsynaptic neurons -synapses releasee NT into extracellular fluid so they can diffuse beyond synaptic cleft |
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what does the locus coeruleus use for NT and where is it located and where does it innervate?
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NE
in the pons fans out innervating almost every part of the brain |
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what is the function of the locus coeruleus?
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involved in regulation of attention, arousal, sleep-wake cycles, learning , memory, anxiety, pain, mood, and brain metabolism
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how is the locus coeruleus activated?
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by new, unexpected, nonpainful stimuli in the environment
least activated when nonvigilant |
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what is the ascending reticular activating system and what are included in it?
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the core of brain stem involved in processes that arouse and awaken the forebrain
locus coeruleus and raphe nuclei |
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when are serotonergic raphe nuclei active and what do they do?
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fire during wakefulness with arousal and activity; less active when asleep
control sleep-wake cycles and the stages of sleep |
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which cells are dopaminergic?
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the substantia nigra in the midbrain projecting axons to striatum
the ventral tegmental area- axons innervating frontal cortex |
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What does DA do from the substantia nigra?
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facilitates initiation of voluntary movement by environmental stimuli
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what is the ventral tegmental area associated with DA also called? what is it involved with?
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mesocorticolimbic dopamine system
reward system that reinforces certain behaviors |
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what are the cholinergic systems?
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basal forebrain complex
pontomesencephalotegmental complex |
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what is involved in the basal forebrain complex and what is its function?
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core of telencephalon, medial and ventral to basal ganglion (medial septal and basal nuclei) innervation to hippocampus and neocortex
ACh function mostly unknown, participates in learning and memory |
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what is involved in the pontomesencephalotegmental complex?
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in pons and midbrain tegmentum
release ACh regulates excitablility of thalamic sensory relay nuclei |
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in order to act on CNS, drugs must first:
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get past blood brain barrier
different per person barrier affected by nutrition and BP |
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how do hallucinogens work? give an example:
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LSD- has behavioral affects causing a dream like state with mixing of perceptions
chemical structure close to serotonin= agonist- inhibits fire of raphe neurons |
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how do many drugs act to produce their affects?
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act on modulatory systems:
dopaminergi serotonergic noradrenergic |
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how do stimulants work?
explain with example: |
cocaine and amphetamine
these affect reuptake of NE and DA causing longer activation in cleft cause increased alertness, self-confidence, exhilaration, euphoria and decrease appetite |
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what are DA and NE synthesized from and what is there general name?
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from tyrosine
catecholamines |
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what does the subfornical organ do/ where is it?
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a part of the telencephalon that lacks blood-brain barrier
cells in subfornical organ project axons into hypothalamus where they can activate ADH |
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what does it mean for a drug to be psychoactive?
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mind altering
inteterfering with chemical synaptic transmission |
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what is the role of the hypothalamus on homeostasis?
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regulates body temperature, fluid balance, and energy balance
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describe the 3 components of motivated behavior:
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1. humoral= hypothalamic neurons respond to sensory signals by stimulating or inhibiting release of pituitary hormones
2. visceromotor= neurons adjust the balance of sympathetic and parasympathetic outputs to ANS 3. somatic motor= neurons incite a motor behavior |
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explain what happens when you are cold:
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body shivers, blood shunted away from body surface, urine production inhibited, body fat reserves are mobilized
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what is the prandial state?
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blood filled with nutrients
energy is stored as glycogen in liver and muscle and as triglyserides in adipose/fat tissue |
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what is anabolism?
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the assembly of macromolecules--glycogen and triglycerides
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what is the postabsorptive state?
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fasting condition b/t meals
during this state glycogen and triglycerides are broken down to provide continuous supply of molecules as fuel for cellular metabolism |
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what is catabolism?
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breaking down complex macromolecules
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how was the role of leptin discovered?
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parabiosis of an ob/ob mouse that was obese and a normal mouse (siamese twins) this reduced the obesity-->so ob mouse lacked gene that codes for protein that monitored fat reserves
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what is the role of leptin, where is it produced?
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regulates body mass by action on neurons of hypothalamus to decrease appetite and increase energy expenditure
produced by adipocytes (fat cells) |
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what are anorectic peptides?
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alpha-MSH and CART
diminish appetite |
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what are orexigenic peptides?
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NPY and AgRP
increase appetite |
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why is the lateral hypothalamus important?
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for initiating activities to remain at homeostasis
output control motivation to eat |
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what is lateral hypothalamic syndrome?
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bilateral lesions of lateral hypothalamus that causes anorexia (diminished appetite)
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what is ventromedial hypothalamic syndrome?
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bilateral lesions of ventromedial hypothalamus
causes over-eating obesity |
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where is the arcuate nucleus?
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base of the 3rd ventricle
its part of hypothalamus |
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elevated leptin leads to the release of what peptides from the arcuate nucleus?
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αMSH and CART
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What affects do αMSH and CART have?
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-humoral response of increased secretion of TSH and ACTH from pituitary (signal to paraventricular nucleus)
-visceromotor response increases tone of sympathetic ANS (raise metabolic rate) -lateral hypothalamus- motor response decreases feeding behavior |
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decreased lepin levels lead to release of what peptides from the arcuate nucleus?
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NYP and AgRP
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what affects do NYP and AgRP have?
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-inhibit secretion of ACTH and TSH (humoral, paraventricular)
-activate parasympathetic nervous system -stimulates feeding behavior (lateral hypothalamus) |
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How does the lateral hypothalamus contribute to feeding behavior?
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neurons and axons passing through this area contribute to the motivation of feeding behavior
one group of neurons uses a NT- MCH to stimulate feeding behavior |
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How does MCH work?
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informs the cortex about leptin levels
motivates the search for food NT used by lateral hypothalmic area |
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what does TSH do?
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it is released from the anterior pituitary and acts on the thyroid to secrete thyroxin which increases metabolic rate
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what is aphasia?
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partial or complete loss of language abilities following brain damage
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what is paraphasia?
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speech error where you substitue incorrect sounds or words
(characteristic of Broca's Aphasia) |
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what is language?
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system by which sounds, symbols, and gestures are used for communication
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explain the process of language:
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-comes to the brain through visual and auditory systems
-the motor system produces speech and writing -essence of language is processing b/t motor and sensory |
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in Greek and Roman times what was thought to control speech?
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tongue
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what is the Wada procedure?
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where a single hemisphere of the brain is anesthetized
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how were aphasias discovered?
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from functional deficits from lesions of certain areas of the brain
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Where is Broca's area and what is it responsible for?
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in the left frontal lobe
speech production |
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where is Wernicke's area and what is it responsible for?
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superior surface of temporal lobe (b/t auditory cortex and angular gyrus)
comprehension of speech |
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describe Broca's Aphasia:
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motor or nonfluent aphasia
person has difficulty speaking even though they understand language heard or read paraphasic errors, anomia, difficulty repeating |
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describe Wernicke's Aphasia:
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speech is fluent, comprehension poor
content of speech doesn't make sense correct words, incorrect sequence |
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which area may relate sounds to their meanings?
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Wernicke's area
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what is the Wernicke-Geschwind model? what does it include?
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model for laguage processing
written word and spoken word includes: wernicke's, brocas, arcuate fasciculus, and angular gyrus |
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Describe the pathway from spoken word in W-G model:
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auditory cortex-> wernicke's-> arcuate fasciculus -> broca's-> motor cortex
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describe the pathway from written word in W-G model:
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primary visual cortex -> angular gyrus ->wernicke's -> arcuate fasciculus -> broca's-> motor cortex
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what is conduction aphasia?
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lesion in arcuate fasciculus connecting wernicke's to broca's area
comprehension is good and speech is fluent, but have difficulty repeating words paraphasic errors, |
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what is anomia?
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inability to find words
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what is agrammatism?
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inability to construct grammatically correct sentences
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Describe what happens with lesions in deaf people:
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broca's- comprehension is good but signing ability is imparied
wernicke's- sign fluently, but w/ mistakes and difficulty comprehending other's signs |
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what is the main artery that is affected when someone has a stroke?
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the middle cerebral artery
lenticulos striates come off of this to bring blood to deep nuclei so middle cerebral important |
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what is mobius syndrome?
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absence or underdevelopment of cranial nerves 6 and 7 (abducens and facial)
loss of facial expressions and control of eye movement inability to smile |
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why do you have the urge to pee right before an exam?
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when stressed muscles tend to contract/ tense up, contracting the bladder causes you to pee
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what is dystonia?
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forceful, sustained contraction of a group of muscles
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what is palmomental reflex?
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contraction of muscles of the chin on the same side as contraction of palm muscles
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what is glabellar reflex?
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a frontal release sign elicited when tapping the forehead repeatedly b/t eyebrows and observing for persistent blinking
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what is snout reflex?
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a frontal release sign elicited when tapping the upper lip and observing puckering of the lips
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what is chorea?
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irregular, unpredictable, brief jerky movements that flit from one body part to another in continuous random sequence
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what is myoclonus?
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spontaneous twitch of a group of muscles that moves a limb across a joint
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what is a tic?
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quick stereotypic jerk of a group of facial or limb muscles
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what is prosopagnosia?
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the inability to recognize faces
from damage to right fusiform gyrus- involved in memory and facial perception results from stroke, trauma, or disease |
