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97 Cards in this Set
- Front
- Back
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glial cells
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half the brains weight
provide neurotropic factors that maintain brain health (e.g. glial derived neurotropic factor GDNF) provide support, during development act as scaffolding for neuron development/migration regulate extracellular fluid composition (e.g. moderate K+ levels, remove excess neurotransmitters) |
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microglia
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immune cell of the brain, phagocytic, proliferate during infection
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astrocyte
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form BBB, wrap processes around blood vessels and whatnot to enclose synapses preventing foreign molecules from entering
buildup of astrocytes indicates infection or injury |
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oligodendrocytes
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myelinators
wraps processes around neuron axons to provide insulation can insulate about 2-3mm, between each myelin sheath is a node of ranvier where there is a high concentration of ion channels |
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satellite cells
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encapsulate entire cell body and synapse
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schwann cells
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mylenators
full myelination = wraps itself around the axon many times 50m/s partial myelination = wraps itself around multiple axons in close proximity 10m/s |
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demyelination
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can result from an abnormality in your immune system
damaged myelin can interfere with neurons ability to create and send action potentials |
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MS
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multiple sclerosis
autoimmune disorder resulting in inflamation and demylenation in CNS tcells, monocytes, compliment system, and microglia degrade myelin along nerve axons (they kill oligodendrocytes) may be triggered by previous viral infection (similar proteins present in virus and oligo) development of sclerotic sheaths |
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sclerotic sheaths
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damaged axons are patched up by astrocytes with scar tissue
result in impaired or loss of action potential if the action potential makes it across, it will likely travel slower than normal |
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types of MS
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relapsing remitting
primary progressing secondary relapsing remitting relapsing progressive |
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plexus
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network of intermingling nerve fibers
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fasiculus
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tract of nerve fibers
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funiculus
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column of nerve fibers
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nucleus
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a group of nerve cell bodies in the CNS
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ganglion
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cluster of nerve bodies that relay information
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afferent
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incoming signals
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efferent
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outgoing signals
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white matter
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fibers with myelin
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gray matter
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cell bodies
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neuroimaging
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non invasive techniques to image structure and function of living brain
structural imaging is useful in identifying injury/intracranial disease functional imaging is useful for diagnosis of metabolic disease and lesions |
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CAT (CT) scan
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rotates around the head, projecting a narrow x-ray beam that is absorbed in small volumes
the quantity of xray absorbed is computed and an image is formed fast, safe, effective method for detecting edema hemorrhage |
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MRI
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magnetic fields are imposed around head, through which radiowaves are directed
detectors measure rf resonance, voxels are computed into a matrix to construct image provides high res images of brain structures, inflammation, bleeding can get not only axial (like CT) but also coronal, mid sagital two types: diffusion and perfusion |
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diffusion MRI
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dead tissue
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perfusion MRI
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compromised (damaged) tissue
dark=low blood flow |
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PET
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positron emission tomography
sensors in PET scanner detect gamma radioactivity of labeled compound data used to compute multi colored 2D or 3D images of the compounds distribution in brain useful for diagnosis of tumors, strokes, Alzheimers, epilepsy |
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CNS
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brain and spinal cord
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PNS
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SNS, ANS (symp and parasymp)
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frontal lobe
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longterm planning
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brocas area
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speech motor, ability to speak
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temporal lobe
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learning, memory, emotion
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wernickers area
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speech recognition and understanding
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parietal lobe
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sensory input, motor function
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occipital lobe
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vision
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NS development
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first organ to develop in embryo
half of the genome is devoted to coding the NS 50000 cells created every sec during intrauterine period, but embryo only keeps half; during the last month of pregnancy and first months of life they are pruned |
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steps in NS development
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sperm+egg > ovum (diploid)
0-24 hours > divides to two daughters 26-28 hours > divides more...4>8>16>32>64 morula forms > blastocyst germ layers develop |
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germ layers
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ectoderm
mesoderm endoderm |
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ectoderm
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NS, skin
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mesoderm
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cardiovascular, skeletal muscle, RBC, smooth muscle in gut,
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endoderm
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GI, lungs, liver, pancreas
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neural plate
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at day 18-25
ectoderm develops into a plate of neural cells that begin to form waves top of the wave is the neural crest, bottom is the neural groove crests will come together and fuse, folding over to form a tube neural tube will close, neural crest cells become part of the sensory system, ANS, facial bones, pigmented skin, dentin |
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spinibifida
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neural tube fails to close at bottom
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ancephaly
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neural tube fails to close at top, no forebrain develops
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actual brain development
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28 days to adulthood
spinal cord has 3 parts prosencephalon mesencephalon rhombencephalon |
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prosencephalon
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develops into:
telencephalon (cerebrum) diencephalon (thalamus/hypothalamus) |
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mesencephalon
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develops into midbrain
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rhombencephalon
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develops into:
mentencephalon (cerebellum and pons) myelencephalon (medulla) |
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CNS supporting systems
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meninges
ventricles and CSF major arteries of the brain |
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meninges
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completely sheath brain:
duramater subdural space arachnoid matter subarachnoid space piamater |
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duramater
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tough mother
outermembrane covers brain attached to periosteum very tough tissue |
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subdural space
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small, volume is only a couple of mL
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arachnoid mater
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spider mother
surrounds the brain looks like spiders web because of blood vessels that are distributed beneath/through it |
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subarachnoid space
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fairly large, vol = 120mL
filled with CSF |
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pia mater
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gentle mother
very tightly attached to the brain |
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dural venous sinuses
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contain CSF
collects blood, recirculates it through jugular veins back to the heart to be reoxygenated |
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falx cerebri
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sickle cell shaped space between cerebral hemispheres
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ventricles
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filled with CSF
provide nutrition and protection from rapid movement (cushioning) lateral, 3rd and 4th ventricles |
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CSF
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cerebrospinal fluid
made at the choroid plexus |
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choroid plexus
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knot of blood vessels that jut out into the ventricles
surrounded by ependymal cells (cells that produce CSF) present in all ventricles |
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CSF flow
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choroid plexus goes through ventricles (lateral have 80% of CSF)
exit via median and lateral apertures of 4th enter subarachnoid space enter venous circulation via arachnoid granulations in the superior sagital sinus |
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CSF for diagnosis
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can provide information:
verify infection (meningitis, encephalitis) determine if there is bleeding in brain (blood will drain to CSF, which normally has no RBC: presence indicates subarachnoid hermorrhage/stroke) immunologic profiling (check for disease states such as MS) cancer (look for cancerous cells in CSF, often cancer of brain comes from tumors in the maters and can metastasize) spinal tap: go in through lumbar with a big needle, draw out 3-5mL CSF, check for bacteria etc. |
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arterial blood supply to brain
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carotid and vertebral supply brain
brain requires 20% of the body's blood, is only 2% of the body's mass |
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carotid
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internal carotid supplies 600-700mL/min
enters brain case via carotid canal if you cut off flow for 10sec you will pass out, 5min will cause brain damage |
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vertebral
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supply 100-200mL/min
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major arteries
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basilar
vertebral cerebral internal carotid |
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basilar artery
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supplies circle of willis
supplies brainstem and cerebellum |
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vertebral
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supplies brain stem and cerebellum
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cerebral
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posterior
middle anterior |
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posterior cerebral
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supplies occipital and medial surface of temporal lobe
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middle cerebral
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supplies most of the lateral surface of each hemisphere
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anterior cerebral
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supplies frontal and medial parietal lobes
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internal carotid
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supplies circle of willis
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circle of willis
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anterior communicating artery
anterior cerebral artery internal carotid artery posterior communicating artery posterior cerebral artery |
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brain stem
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pons and medulla
contains nuclei that control HR, BP respiration sleep cycles bladder control sneeze/cough/hiccup balance |
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medulla
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contain ascending and descending fiber tracts:
info from spinal cord and sensory systems travel up, commands from higher brain travel down pyramidal decussation: where nerve fiber tracts cross, right brain = left body vice versa controls: -HR BP -sneeze/cough/hiccup -balance (olive of inner ear) -resp rate |
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pons
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ascending and descending tracts allow communication between cerebrum and cerebellum
-sleep cycles -resp rate |
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midbrain
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corpora quadrigemini:
superior colliculus (visual) inferior colliculus (auditory) cerebral peduncles are fibers tectum - roof tegmentum - floor substantia negra |
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tectum
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roof of midbrain:
contains corpora quadrigemina |
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tegmentum
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floor of midbrain:
contains substantia negra, red nuclelus, medial lamniscus, spinal lamniscus |
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substantia negra
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dark substance
colored via melanin critical for fine voluntary movement control maintains muscle tone |
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red nucleus
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highly vascularized
rich in iron content regulates unconscious movement (balance) |
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medial lamniscus
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ribbon of fibers
sensory input travels up to the brain vibration precise touch proprioception |
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spinal lamniscus
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ribbon of fibers
sensory movement travels up to brain pain crude touch temperature |
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diencephalon
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hypothalamus and thalamus
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hypothalamus
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multiple nuclei
feeding center (drive to eat, sense of satiation) body temp (heat, sweating + vasodilation in periphery to decrease) water balance (informs you of dehydration) ANS circadian rhythms (sleep patterns and activity levels) |
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thalamus
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lateral geniculate nucleus (vision)
medial geniculate nucleus (hearing) ventroposterior nucleus (somatosensory) |
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pituitary gland
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endocrine system
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epithalamus
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habenular nucleus (emotional response to odors)
pineal body (onsets puberty + diurnal cycle) |
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cerebellum
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dorsal to brainstem, caudal to cerebrum
linked to CNS via cerebral peduncles vermis flocculus lateral hemispheres |
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vermis
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in cerebellum
controls posture, locomotion, fine motor control |
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flocculus
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in cerebellum
controls balance and eye movement |
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lateral hemispheres
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of cerebellum
control learning complex motor habits |
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cerebrum
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"basal ganglia"
comtrols planning, organization of voluntary motor function composed of several nuclei lentiform caudate putamen substantia negra |
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corpus striatum
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lentiform nucleus
caudate nucleus putamen |
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parkinsons
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lack of dopamine
you can track this via PET scan with 18F-DOPA substantia nigra is deteriorating -asymptomatic until 70-80% are gone development of lewy bodies chronic neurodegenerative disease |
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parkinsons pathophysio
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nigrostriatial pathway between motor cortex and motor neurons in spinal cord is destroyed (normally outputs of striatum control fine voluntary movement)
loss of substantia nigra neurons disrupts basal ganglia dopamine cant cross |
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parkinsons cardinal features
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stooped position
uncontrolled shaking arms carried in front, dont swing legs stiff, bend at knees and hips rigidity short shuffling gait slowness and poverty of movement bradykinesia/hypokinesia resting tremors postal impairment unblinking, masklike face often pill rolling tremor in fingers dementia, depression, anxiety |
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parkinsons aetiology
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oxidative stress
gene mutations infections environmental toxins parkinsonism via dopaminergic antagonists |
