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Hippocrates - "father of medicine" - brain is the center of intellegence & personality - believed that the brain was involved in sensation - brain is the seat of intelligence Galen - embraced hipprocates views - dissected sheep brains - proposed cerebrum stored senstation - proposed cerebellum controlled muscle movement - fluid mechanical theory Andreas Vesalius - anatomist that drew detailed structure of brain - wrote De Humani Corporis Fabrica Rene Descartes - reasoned that humans, not animals, have a mind/soul seperate from the brain - chief advocate of the fluid mechanical theory Charles Bell & Francois Magendie - proposed sensory (cerebrum) & motor (cerebellum) fibers - experimental ablation method - localization of functions in different brain areas Franz Gall - phrenology: correlation of skull structures to personality traits - false Paul Broca - studied patients with speech loss - discrete regions of the human cerebrum for speech Theodor Schwann - proposed cell theory in animals Mattias Schleiden - promoted cell theory in plants Waldheyer - proposed neuron doctrine - each nerve cell is a distinct genetic and anatomical unit with axons and dendrites that have distinct andings Golgi - opposed neuron doctrine - proposed reticular theory - soaked brain tissue in silver chromate, "golgi stain" - axons and dendrites from a continuous network or reticulate of nerve processes - nobel prize with cajal for physiology and medicine in 1906 Santiago Ramon y Cajal - nobel prize with golgi for physiology and medicine in 1906 - accepted neuron doctrine - also made drawings Sherrington - synpases - proposed that nerve cells form pathways by communication with each other through junctions Galvani - neurons are electical wires, not tubes, that conduct electical currents to and from the brain Flourens - expiremental ablation method - cut out parts of brain to see what happened - cerebellum does play a part in the coordination of movement neuroscientists: gross organization of nervous system Galen& Vesalius neuroscientists: electrical nature of nervous system communication Franklin & Galvani neuroscientists: sensory & motor information is seperate Magendie & Bell neuroscientists: functional localization in nervous system Broca & Gall & Flourens neuroscientists: nervous system is made up of discrete cells called neurons Cajal & Golgi neuroscientists: neurons communicate chemically through synapses Sherrington neuroscientists: cell theory plants - Schleiden animals - Schwann neuroscientists: neuron doctrine proposed- Waldheyer accepted - Cajal opposed - Golgi definition: cell theory the cell is a discrete, basic unit that it assembled into tissues in animals each cell is a distinct anatomical & genetic unit definition: neuron doctrine each cell is distinct genetic & anatomical unit with axons & dendrites that have distinct endings accepted after golgi & cajal stained neurons and processes definition: recticular theory a network of living material is multinucleated axons and dendrites form a continuous network or rectiulate of nerve processes (as in the vascular system) definition: fluid mechanical theory fluid (humor) from venticles pump down hollow tubes like blood vessels to inflate (contract) muscles cellular components of the nervous system - neurons - glia - microglia - ependymal cells - meningial cells neurons - reside in grey matter in nuclei & ganglia - parts of neuron (soma, axon, dendrites) - classified by shape, function, and transmitter neurons classified by shape - unipolar/monopolar - bipolar - multipolaar neurons classified by major neurotransmitters - dopaminergic - andrenergic - cholinergic neurons classified by function - motor, sensory, sympathetic, ect. - projections, interneuron glia cells - reside in grey & white matter - insulating, supporting, and nourshing neighboring neurons in the brain - oligodendrocytes (in CNS) - astrocytes (in CNS) - schwann cells (in PNS) - microglia - ependymal cells oligodendrocytes - glia cells in CNS - mostly in white matter, but also in grey matter when myelinated axons transverse - provide myelin sheath around axons in brain & spinal cord - myelinates large diameter axons in CNS - do not ensheathe small diameter axons that can directly appose other axons astrocytes - glia cells in CNS - make BBB - "clean up system" of the brain - most numerous glia in the brain - contribute to BBB, nodes of ranvier, synaptic endings, dendrites, and neurons - regulate chemical content of extracellular space - haven enlarged end-feet on processes abut on capillaries - two types 1. protplasmic (in grey matter) 2. fibrous (in white matter) schwann cells - glia cells in PNS - form myelin sheath - myelinates only in a single axon in PNS - participates in development & regeneration of PNS microglia - glia cell - carry out immune functions - functions as phagocytes to remove debris left by dead or degenerate neuron and glia ependymal cells - glia cells - line ventricles within the brain meningial cells - covers brain & spinal cord - "suit of armor" for brain - 3 layers 1. dura matter: outerlayer closest to skull 2. arachnoid matter 3. pia matter: innerlayer closest to brain dura matter - outlayer of meninges - closest to skull arachnoid matter - middle layer of meninges pia matter - innerlayer of meninges - closest to brain soma - rough sperical part of neuron - contains some organelles found in animal cells axons - found only in neurons - no rough ER, few ribosomes - proetin composition of axon membrane is fundamentally different than soma membrane axon terminal - site where axons come in contact with other neurons & place info on them - site of synapse - terminal arbor - innervation - presynaptic membrane - postsynaptic membrane dendrites - function as antenna of neuron - covered with thousands of synapses - repectors detect neurotransmitters in synaptic cleft axon hillick beginning of axon axon proper middle of axon terminal arbor - axon terminal/boutton - branches that form a synapse on dendrites or cell bodies in the same region innervation - on axon terminal - when a neuron makes a synaptic contact with another cell presynaptic membrane - consist of axon terminal postsynaptic membrane - may be the dendrite or soma of another cell synaptic cleft - space between presynaptic & postsynaptic membrane synaptic transmission - transfer of info at the synapse from one neuron to another neurotransmitter - chemical signal in the postsynaptic membrane that is store in & release from postsynaptic vesicles within the terminal cytoplasm of axon terminal - no microtubles - contains numerous small bubbles of membrane, synaptic vesicles, that measure about 50 nm - inside surface of the membrane that faces the synapse has a dense covering of proteins - numerous mitochondria , indicating a high energy demand cytoplasm of axons - has microtubles - no synaptic vesicles - no rough ER - few, if any, ribosomes - protein composition differs from soma axon collaterals - branchs from axons recurrent collaterals - axon collaterals that return to communicate with the same cell that gave rise to the axon or with dendrites of neighboring cells the thicker the axon the faster th nerve pulse travels axoplasmic transport - movement of material from the soma to the axon terminal - normal flow anterograde transport - protein kinesin moves only material from the soma to the terminal - process is feuled by ATP retrograde transport - mechanism for movement of material up the axon from the terminal to the soma - believed to provide signals to the soma about changes in the metabloic needs of the axon terminal - provided by protein dynein dendritic spines - specialized structures of dendrires of some neurons - recieve some types of synaptic input - discovered by cajal - believe to isolate various chemical reactions that are triggered by some types of synaptic activation - sensitive to amount and type of synaptic activity, individuals with cognitive impairments, and quality of environment during early development and in adulthood stellated cells - star shaped pyramidal cells - pyramid shaped primary sensory neurons - cells with connections that information is delievered to the nervous system by neurons that have neurites in the sensory surfaces of the body; such as skin & retina of the eye motor neurons - neurons that have axons that form synpases with the muscles - command muscle movement interneurons - most neurons - neurons in the nervous system that form connections only with other neurons Golgi type I neurons - projections neurons - neurons that have long axons that extend from one part of the brain to another - in cerebral cortex, prymidal cells usually have long axons that extend to other parts of the brain Golgi type II neurons - local circut neurons - neurons that have short axons that do not extend to other parts of the brain - in cerebral cortex, stellate cells have axons that never extend beyond the cerebral cortex types of classification of neurons - number of neurites - dendrites - connections - axon length - neurotransmitter node of Ranvier - short length where the axon membrane is exposed - cause when the sheath is interrupted periodically myelin - membrane that insulate axons - spirals around the axons in the brain the absence of ribosomes in the axon predicts... that the protein in the axon terminal must be provided by the soma via axoplasmic transport a large number of mitochondria in the axon terminal predicts... a high energy demand the elaborate structure of dendritic trees appears ideally suited for the receipt of information coming in, where.... most of the synapses are formed with the axons of other neurons from the time of nissl.. it has been recognized that an important feature of neurons is rough ER rough ER - a site of the synthesis of proteins destined to be inserted into the membrane cytosol - watery fluid inside the cell soma - salty - potassium rich - seperated from the outside by neuronal membrane adenosine triphosphate (ATP) energy currency of the cell the functions of neurons... can not be understood with understanding the structure and function of the membrane and its associated proteins mitochondria is the site of.. cellular respiration Wallerian degeration - the degration of axons that occurs when they are cut - occurs because the normal flow of materials from the soma to the axon terminal is interrupted receptors - specialized proteins in the postsynaptic membrane - detect neurotransmitters in the synaptic cleft alzheimer's disease - a progressive degenerative disease of the brain - characterized by dementia - always fatal cerebral palsy - a motor disorder -caused by damage to the cerebrum at the time of birth depression - a serious disorder of mood - characterized by loss of appetite, insomnia, and feelings of dejections epilepsy - a condition characterized by periodic disturbances of brain electircal activity - can lead to seizures, loss of consciousness, and sensory disturbances multiple sclerosis - a progressive disease - affects nerve conduction - characterized by episodes of weakness, lack of coordination, and speech disturbance parkinson's disease - a progressive disease of the brain - leads to difficulty in initiating voluntary movement schizophrenia - a severe psychotic illness - characterized by delusions, halluciations, and bizarre behavior spinal paralysis - a loss of feeling and movement - caused by traumatic damage to the spinal cord stroke - a loss of brain function - caused by disruption of the blood supply - usually leading to permanent sensory, motor, or cognitive deficit