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78 Cards in this Set
- Front
- Back
nervous system
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- organized constellation of cells specialized for repeated conduction of electrical signals within and between cells
- integrate signals of converging neurons, generate new signals, and modify properties of neurons based on their interactions - vary on complexity and behavioral output - neurons |
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evolution of nervous system
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- cnidarians first animals with true tissue = nerve nets
- Platyhelminthes = nerve tracts - echinoderms = nerve rings - molluscan = a lot of centralization and sense organs - humans = huge number of centralization and sense organs |
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trends in evolution of nervous system
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- increase number of nerve cells
- concentration of nerve cells forming masses of nerve cell bodies (ganglia) - increased number of interneurons and more complex synaptic connections - specialization of function - cephalization |
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specialization of function
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- greater and greater specialization within ganglia leading to brain and spinal cord
- transmission of impulse in 1 direction = afferent - efferent - effectors |
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central nervous system (CNS)
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- consists of relatively large structures such as the brain, spinal cord in which large numbers of neurons and support cells are anatomically juxtaposed and interact to achieve integrative functions
- rich with cell bodies and processes of neurons - interneurons confined - sensory neurons = convey information to CNS - motor neurons = convey information out of CNS to control muscles or other effectors - all signigicant integration and processing of neural activity - no peripheral integration |
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effector
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- organ, tissue, or cell that acts under the direction of the nervous system
- muscles and glands - carries out functions such as motion or secretion |
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peripheral nervous system (PNS)
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- nerve endings and receptors
- nerve fibers - ganglia - consist of all processes and cell bodies of sensory and motor neurons that are present outside CNS - autonomic ganglia and enteric nervous system - no sensory to motor synapses |
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ganglia
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- sits outside spinal cord
- dorsal root = sensory (afferent) - autonomic = sympathetic, parasympathetic (efferent) |
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parasympathetic
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- goes inside the organs
- preganglionic and postganglionic - always ACh and excitatory - maintains things as status quota - emerge from cranial region and sarcratic region - short postganglionic and long preganglionic - mediate rest and digest functions - ganglia located mostly at or near the effectors - preganglionic neurons exit from the cranial and sacral region = craniosacral division - release ACh = cholinergic - promote proceses that restore body reserves of energy |
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sympathetic
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- ACh at preganglionic and noradrenegic at postganglionic
- short preganglionic and long postganglionic - emerge in middle - fight or flight = increase ability to invade - ganglia located mostly near spinal cord - preganglionic neurons exit in nerves of thoracic and lumbar regions of spine = thoracolumbar division - release catecholamines = adrenergic - promotes mobilizing body energy reserves and inhibits some processes that restore reserve |
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2 divisons of PNS
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- somatic nervous system
- autonomic nervous system |
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somatic nervous system
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- controls skeletal (striated) muscles that generally produce voluntary movements
- somatic effectors = skeletal muscle - sensory reception of external stimuli and transmission of sensory - controls muscles of locomotion and other body movements, speech, and breathing - observable behavior - touch, hearing, vision, taste, olfaction = sensory receptors - motor and sensory neurons exit and enter CNS in cranial and spinal nerves - 12 pairs of cranial nerves with specialized functions - dorsal root ganglia = enlargements of dorsal roots outside the spinal cord - somatic motor neurons directly synapse on muscle fibers - somatic motor association area coordinate learned movements |
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autonomic nervous system
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- controls autonomic effectors
- internal effectors = include all neuron-controlled effectors other than striated muscle - cardiac muscle, smooth muscle, glands - sensory neurons that convey information to CNS about internal organs - smooth muscle - exocrine glands = discharge secretions into environment or into internal body cavities - few endocrine glands - acid secreting cells of stomach - pacemaker and other regions of the heart - BAT - swim bladders - integumatory chromatophores - sympathetic, parasympathetic, enteric |
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development of nervous system
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- starts as neural tube = notocord folds in the neural plate
- specialization begins at the head |
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principles of brain function
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- brain function is somewhat localized
- brains have maps - size matters - vertebrate brain evolution - neural circuits are plastic |
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brain function is somewhat localized
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- neural activity is measured as increased blood flow
- neurons organized in circuits so they can elicit a coordinated, adaptive response of effectors - neurons in different regions play different functional roles - localization of function - function involve a circuit in brain = network of synaptically interconnected and interacting neurons |
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brains have maps
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- brain maintain information about anatomical organization in terms of topographic representation
- related to specific regions having specific functions - maps = topographic representation of body's anatomy - somatotopic map = map of body projected to brain area - maps aren't universal - record and recall parameter of where stimulus occur or an effector is to be controlled |
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size matters
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- more neurons = more complex integration
- larger size doesn't mean you're more intelligent - increase in processing capabilites |
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vertebrate brain evolution
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- repeated expansion of forebrain = birds and mammals have complex
- more complex = cerebral cortex - dorsal pallium = neocortex - elaborations of preexisting structures - deeper structures of midbrain and hindbrain |
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neural circuits are plastic
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- synapses change
- long term memory requires changes in "wiring" of brain - synapses change with development, maturation, experience - short-term memory can be disrupted - long-term memory stored more permanently = changes in strengths of synaptic interconnections of neurons - neuronal proliferation |
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general functional features of nervous system
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- sensory receptor cells transform environmental stimuli into electrical signals
- central interneurons integrate signals from sensory receptors and other signals arising, generating integrated pattern of impulses - motor commands are sent out from CNS to effectors |
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2 major trends characterize evolution of nervous system
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- centralization = structural organization in which integrating neurons are collected into central integrating areas
- cephalization = concentration of nervous structures and functions at the head |
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4 terms for bundles of nerve axons
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- nerve = bundle of axon in PNS
- connective = between ganglia in CNS - tract = within ganglion - commissure = between right and left sides of bilaterally symmetrical ganglion |
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afferent
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- neurons that carry nerve impulses away from CNS
- peripheral nerves |
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efferent
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- neurons that carry nerve impulses away from CNS
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CNS consist of 2 types of tissue
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- gray matter
- white matter |
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gray matter
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- composed of intermingled neuronal cell bodies, processes, and synaptic contacts
- external of brain - internal of spinal cord |
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white matter
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- consists of entirely of tracts of myelinated axons which imparts white appearance
- external of spinal cord - internal of brain |
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2 types of circuits of spinal cord
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- local circuits
- ascending/descending |
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local circuits
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- exist within single segments of spinal cord
- sensory neurons entering a segment control motor output |
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ascending/descending
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- sensory input relayed to brain
- higher integration - information exchanged between spinal cord and brain |
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nerves in PNS that connect to CNS
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- cranial = connect to brain
- spinal = connect to spinal cord - brain receives sensory input from sensory neurons in cranial nerves and via ascending pathways from spinal cord - brain motor neurons travel within nerve control effectors of the head - spinal nerves arranged segmentally - spinal cord receives sensory input through dorsal roots of spinal nerves - sends motor output to periphery of body via ventral roots of spinal nerves |
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brain structural organization
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- 3 major regions: midbrain, forebrain, hindbrain
- 5 subdivisions: * forebrain = tetencephalon, diencephalon * midbrain = mesencephalon, * hindbrain = metencephalon, myelencephalon |
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hindbrain
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- connects to spinal cord
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medulla oblongata
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- ascending and descending nerve tracts
- gray matter host a variety of vital nuclei reserved for cranial nerves and sensory neurons - connect brain with spinal cord relaying sensory info to thalamus and other parts of brain stem - cardiovascular centers = adjusting heart rate and strength of contraction - respiratory rhythmicity centers = set basic pace for breathing |
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pons
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- situated between midbrain and medulla
- relay signals from cortex to assit in control of movement - control of sleep and arousal |
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pontine motor nuclei
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- part of pons which store memory of intention during motor activity
- modification of actions or error correction - learning motor skills |
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cerebellum
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- 2nd largest part of the brain
- important in motor corrdination - motor neurons in spinal cord activate muscles as result of 3 inputs - input from local spinal circuits - descending input from brain - sensory input - movement of muscle provides sensory feedback |
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output neuron is purkinje cell
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- for cerebellum
- between molecular and granular layer - enormous set of dendrites - axon carries information outside cerebellum |
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climbing fibers
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- cerebellar inputs
- excitatory 1:1 synapses with purkinje cells - may convey error signals |
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mossy fibers
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- cerebellar inputs
- excitatory input to granule cells - may convey broad info about sensory input of movement |
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interneurons
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- granule cells, stellate cell, basket cell, golgi cell
- granule cells have parallel fibers in molecular layer = excitatory - all other inhibitory and mediate different types of inhibition |
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motor task learning
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- involve changes in long term depression at synapses of parallel
- involve changes in long term depression at synapses of parallel fibers onto purkinje fibers - involves hetersynaptic interaction in which climbing fiber depresses synaptic action of parallel fiber as it synapses on purkinje cell |
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midbrain
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- processes visual and auditory information
- helps maintain consciousness - generate autonomic motor responses = reflexes - collicuous - motor nuclei for 2 cranial nerves - reticular formation headquarters - nuclei involved in maintaining muscle tone and posture - nucleus that regulates motor output of basal ganglia = substanta nigra - bundles of nerve fibers linking cerebrum to cerebellum and brain stem = peduncles |
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colliculi
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- superior = control reflexes in response to visual stimuli
- inferior = control reflexes in response to auditory stimuli |
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cerebrum
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- divided into 2 cerebral hemispheres
- superficial layer of gray matter = cerebral cortex - conscious thought - memory storage and processing - sensory processing - regulation of skeletal muscle contraction - fissures = deep grooves - gyri = folds - sulci = shallow depression |
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cerebral hemisphere divided into lobes
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- frontal lobe, parietal lobe, temporal lobe, occipital lobe
- fifth lobe, insula, medial to lateral sulcus |
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left cerebral hemisphere
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- general interpretive and speed centers
- responsible for language based kills - important for analytical tasks like mathematics and logic |
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right cerebral hemisphere
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- analyze and interprets sensory information
- enables identification by touch, smell, sight, taste - allows recognition of faces and 3D relationships |
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corpus callosum
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- connect left and right hemisphere
- thick tract of white matter connecting 2 cerebral hemispheres - carries about 4 billion impulses per second |
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crossing over
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- sensory information from one side of body ends up on opposite side
- motor commands from one side of brain go to opposite side of body - occurs in brain stem and spinal cord |
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nuclei
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- groups of nerve cell bodies in CNS
- basal nuclei in each cerebral hemisphere - subconscious control of muscle tone - helping direct movements like walking and running |
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primary motor cortex
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- sends voluntary commands to skeletal muscle
- neurons here = pyramidal cells - activate spinal motor neurons - organized by body part but the different ares control organized movement rather than individual muscles - directly activates spinal motor centers to generate movement |
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pre-motor cortical region
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- complex mosaic of areas involved in planning and organizing movement
- especially of limbs and face |
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cerebellum and basal ganglia
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- connected to cerebral cortex in looping circuits
- cerebellum is active in coordinating movements and in motor learning - basal ganglia involved in initiation of movements by dis-inhibition - parkinson's and huntington's disease originate with abnormalities here |
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primary sensory cortex
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- receives general somatic sensory information
- processes sense of touch, pressure, pain, vibration, taste , temperature |
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somatic sensory association area
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- monitors primary sensory cortex activity
- allows recognition of light touch |
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integrative centers
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- perform complex processes and are restricted to either left or right cerebral hemisphere
- speech center of Broca's are or motor speech area = regulates pattern of breathing and vocalization for speed |
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location of speech function
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- neurons in wernicke's area send axons via arcuate fasciculus to broca's area
- wernicke's area involved in understanding spoken word - broca's area initiates grammatical speed |
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basal ganglia
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- group of nuclei in brain including the striatum, pallidum, substantia nigra, and subthalamic nucleus
- active in learning, habit formation, certain psychiatric disorders - set of nuclei or cluster of brain neurons located in forebrain and midbrain under cerebral cortex - important in selecting movement, suppressing competing or unwanted movement areas: caudate nucleus, globus pallidus - imporatn areas: caudate nucleus, putamen, globus palidus - caudate nucleus and putamen = receive excitatory input from many parts of cerebral cortex - send inhibitory neurons to globus pallidus |
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indirect pathway
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- through basal ganglia neurons from cerebral cortex excite striatal neurons, which inhibit neurons in globus pallidus and pars interna
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globus pallidus neurons
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- normally inhibit neurons in thalamus that promote movement
- when globus pallidus is inhibited = thalamus is dis-inhibited and promotes movement |
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long term memory
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- declarative: diencephalon, hippocampus
- procedural: amygdala, cerebellum |
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limbic system
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- receives signals from neurons that either secrete serotonin or norepinephrine or form neurons that secrete both
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diencephalon
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- surronds 3rd ventricle
- chroid plexus in anterior portion - posterior portion contain pineal gland = produces melatonin that helps regulate day-night cycle - thalamus and hypothalamus |
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thalamus
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- relay and processing center for sensory information
- composed of 2 halves separated by 3rd ventricle - relay point and filter for sensory information - sends some information to primary sensory cortex and rest to subconscious centers in brain - plays role in coordinating voluntary and involuntary motor commands |
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hypothalamus
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- centers for emotions, autonomic functions, hormone production
- subconscious centers involved with rage, pleasure, pain, sexual arousal - adjusting autonomic centers in pons and medulla oblongata - coordinating nervous and endocrine system activities - secretion of hormones - sensation of hunger and thirst - coordinating voluntary and autonomic functions - regulating normal body temperature - coordinating daily activity cycles |
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biological clock
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- endogenous physiological timing mechanism
- rhythmically modulate functioning of cells, tissues, organs - temporal organization = timed pattern of change in physiology or behavior thats independent from change in environment - operations of nervous system = controlling physiological and behavioral processes via nervous and neuroendocrine output - orchestrate daily and seasonal changes - free-running - times pattern of physiological change - endow an animal with an intrinsic temporal organization |
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endogenous rhythms
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- output of clock
- rhythms that continue in absence of environmental information about time - ancient feature of life - correlate with natural history and compensate for temperature |
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rhythm
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- circadian rhythm = endogenous rhythm that has a period of about a day
- in phase = two rhythms occur synchronously - free running rhythm = biological rhythm that persists when environmental cues are absent - entrainment = process by which biological rhythm is brought into phase with environmental rhythm - phasing factor = environmental rhythm |
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adaptive advantages of biological clocks
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- predictive = enable animal to anticipate and prepare for regular environmental changes
- feed-forward control = initiates changes in physiological systems, rather than correcting for changes after happening - photoperiod = number of hours of daylight in a 24 hour day - timing of processes during periods of 24 hour day when environmental cues are vague or unreliable - changes in photoperiod - use sun to determine compass direction |
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timekeeping mechanism
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- depends on rhythmic alternation between enhanced and inhibited expression of key clock genes
- enhanced expression leads to increased levels of protein - protein negative factor for expression = suppresses - circadian oscillator |
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suprachiasmatic nuclei
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- location of master circadian clock in hypotalamic region of diencephalon
- dorsal to optic nerve at optic chiasm - express rhythmic circadian activity of clock genes - ventral and dorsal (SCN) differ in NT, intrinsic rhythmicity and connections with other brain areas |
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pineal gland
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- small, unpaired gland that forms embryolligaity as an evagination of roof of brain and is found in all vertebrates
- melatonin = compound synthesized from AA tryptophan - not independently rhythmic = circadian control from SCN |
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clock mechanisms based on rhythm of gene expression
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- involve oscillation of proteins in individual cell by alternating up and down regulation of clock genes
- in mouse, clock components include CLOCK and BMAL1 - regulatory targets of these factors are teh 3 period genes - constant production of clock genes |
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CLOCK and BMAL1
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- transcription factors which are able to form heterodimers and activate transcription upon binding to E-box promoter elements
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3 period genes
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- (PER) and CRY genes that function as negative regulators, block activation by CLOCK, BMAL1
- PER1, PER2, and CRY1 accumulate in nuclei of SCN neurons at end of subjective day and disappear at end of circadian night |
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circadian rhythm
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- don't control
- can choose to ignore - babies have terrible circadian rhythm = isn't fixed - need light and dark in order for it to behave appropriately |