Nervous System PDF

NS overview role: collect, process, and respond to both internal and external stimuli components: neurons + neuroglia cells 1 astrocytes (...

NS overview role: collect, process, and respond to both internal and external stimuli components: neurons + neuroglia cells 1 astrocytes (physical support support. > - (cerebral spinal fluid) Ependinal neurons can be form determines function 2. CNS 3. Microglia ("immune system" ( - unipolar · 4. Oligodendrocytes (myelin - pseudo-unipolar PNS - bipolar =- schwann cells (mydin) - ↓ - multipolar satellite (physical ( · cells support The Nervous System: CNS & PNS  variations many simple or complex ? Introduction Neurons communicate via electrical and chemical signals in order to gather information, process it, and direct an appropriate response How? Sensory systems range from very simple (ex: eyespots) to simple (ex: nerve networks in cnidarians) to highly complex (ex: humans) Complexity/size of nervous system indicates lifestyle – predators tend to be ‘smarter’ and have larger, more complex nervous systems for rapid responses & problem-solving; sessile animals do not have large/active brains dumber herbivores - is there predators-smarter · spephalization ? to out smart prey bigger /moving = smarter brain) more complex NS larger Human Nervous System Divided into: PNS (peripheral nervous system) providing sensory & motor signals CNS (central nervous system) processing information Additional terminology: Nerves: bundles of axons from many neurons acting as ‘roads’ to carry information (vary in diameter depending on how ‘popular’ the route is) Ganglia: clusters of neurons outside the brain Glia: nervous support cells (assist neurons) helping neurons  Schwann cells in x only => aka PNS satellite Cells Glia D Astrocytes: physically support; blood/brain barrier keeping bad stuff out of brain Microglia: immunity/CNS defense Oligodendrocytes: CNS support (analogous to Schwann cells in PNS) Ependymal cells: produce, circulate cerebrospinal fluid -leak = way for bacteria - schwann cells to get in ↳ for test ? include ? Human Nervous System Con’t Dorsal nerve cord in embryo develops into CNS processing level , higheaneurons bodies cell axons Central canal (spinal cord) and ventricles (brain) contain cerebrospinal fluid s more Made from blood filtering across a permeable region of the blood-brain barrier Carries nutrients, hormones, and wastes Gray matter: neuron cell bodies inside ; deeper In brain, cortical; in PNS, medullary White matter: axons outside In brain, medullary; in PNS, cortical Interactions Between PNS & CNS brain need 3 neurons to do something ↑ -sensory-motor-interneurons Basic concept: PNS gathers m information, relays it to CNS, which determines how to interneuron respond sensory >Simplest (3 neur) - Simplest example is a reflex: a stereotypical, involuntary response to a stimulus (done without conscious thought) interneurons & detect space position humans don't rely on reflexes of body to learn due to ability > adult baby - lose reflexes  PNS Divisions & Afferent nerves carry information toward the CNS sensory info Efferent nerves carry information motor contractions away from the CNS; two options: - - movement Motor (part of somatic): communicate Caigestion with skeletal muscle (mostly voluntary) stomach takes regulation ; care of self ; independent of CNS/PN Autonomic: communicate with smooth & cardiac muscle (mostly involuntary); impacting glands, organs Sympathetic (excitatory, ”fight-flight- some animals freeze ; helps freeze”) - humans will shut down things (ex certain muscles) camouflage when in danger - no digestion , more blood to Parasympathetic (calming, “rest and digest”) opposite to sympathetici maintenance off more blood for digestion ; turn muscles  to cerebrum der more num ↳ I The Brain · indicat ef - environ - prey v. predator - der. Size Divided into 3 regions: cerebrum Forebrain: smell, sleep regulation, learning, complex processing Midbrain: directs sensory input to appropriate brain regions Hindbrain: involuntary vital · survival instincts processes (breathing, circulation, motor coordination) Proportions differ between species and offer clues about lifestyles ratios of brain comp change - Smell Brain Anatomy Overview Brainstem relaying information Connects to spinal cord Regulates vital functions Diencephalon Between brainstem & cerebrum Emotions, hormones, behaviors Cerebellum Posterior from brainstem Balance, fine motor control Cerebrum learning, interpretation ‘brain’ Receive/synthesize information Brainstem rate's breathing Medulla Oblongata heart Responsible for maintaining/regulating normal vital processes w/pons Pons Communication between cerebellum & cerebrum w/medulla oblongata regulate some vital functions (balance, swallowing) Midbrain Relay auditory, touch, & visual information Help coordinate body movement, regulate consciousness  Diencephalon Thalamus mail room - sorts in fo Transfer sensory input from brainstem to cerebrum Influences mood/emotions, learning, consciousness Epithalamus melatonion production Location of pineal gland (producing melatonin, influences cyclical - behavior) Hypothalamus Maintain homeostasis, direct hormonal cascades via pituitary gland not just estrogen/testerone Cerebellum Posterior to brainstem, with wrinkled appearance similar to cerebrum but smaller Used in proprioception: the sense of bodily location in space; highly valuable for balance, coordination, muscle memory know location evening - of limbs reg/control 24/7 of muscles Cerebrum - intelligence factor determining of neurons kind very complex neuron density Largest part of brain type connections of Functions in voluntary actions (motor control, behavior, analysis/response to sensory information, memory & learning, abstract thought, and more Highly wrinkled due to folds to increase surface area Two halves (R/L) connected by the corpus callosum Conscious Thought I decision making balance movement - I vision hearing - - Physiology Some brain functions are very localized but most involve more than one area physiological regulation lots lower of HR breathing , shallow ! X dreaming Ex: sleep: brainstem (reticular formation in midbrain & pons) + cerebrum (dreaming) + diencephalon (suprachiasmatic nucleus (SCN) of hypothalamus regulates melatonin from pineal gland) > - sleepiness Some brain functions that are localized can ‘move’ in response to - make new connections damage (remodeling) due to neuronal plasticity: changes to synapses Ex: some brain injuries and malformation can be recovered from ( Memory is a form of neuronal plasticity: short-term memories come from temporary connections in the hippocampus that are either discarded or transferred to long-term memory in the cerebral cortex brains can rewire themselves have based on what brain already  StimulI takes brain time stroke retraining to of a brain respond extent Motor recovery after stroke (fMRI). Longitudinal fMRI studies showing the recovery after stroke during a right finger tapping task. As is shown, the contralateral cortex is progressively representing the right hand (Rıos et al., in preparation). source “Structural MRI, which visualizes the size and shape of structures in the brain, revealed evidence of a massive stroke that targeted both hemispheres. Daniel was missing about a quarter of his cerebral cortex, the outer layer of the brain associated with higher level processes such as thought, memory, consciousness, language and movement. The motor cortex, one of the principle areas involved in movement, is a U-shaped strip of brain tissue that goes down either side of the head. Daniel shockingly only has cerebrospinal fluid where much of the motor cortex should be. He also has no frontal eye fields on either side — the brain regions that control eye movement — even though he can move his eyes just fine.” source brain can wire itself in different ways