Learning objectivesDescribe the basic components of the CNS and PNS and sketch out the flow of informationCompare and contrast white and grey matterWhat is the function of the 4 cortex lobes, thalamus, hypothalamus, and brainstemWhat is a spinal cord tract and which ones are involved with motor control and somatosensory processingDraw and label a cross-section of the spinal cordWhat is a reflex arc?Draw, label and describe the patellar tendon reflex and ipsilateral withdrawal reflexFlow of informationAfferent-CNS-EfferentAfferent division- receives input from sensory stimuli and visceral stimuliTakes this information from PNS to CNSInformation then reaches CNS (brain and spinal cord), where processing occursEfferent division- output from CNS to PNS (periphery nervous system)Splits into somatic and autonomic nervous systemSomatic nervous systemMotor neuronsSkeletal muscleAutonomic nervous system splits into:Sympathetic nervous systemSmooth muscleCardiac muscleExocrine glandsEndocrine glandsParasympathetic nervous systemSmooth muscleCardiac muscleExocrine glandsEndocrine glandsEnteric nervous systemDigestive organs onlyBesides the requisite blood vessels and connective tissue, the central nervous system is composed of neurons=nerve cellsThere are about 20 BILLION in the brain alone, that convey, process, and store informationDifferent neurons release different neurotransmittersTypically have lost the ability to divide, so they cannot be regenerated if injuredCentral Nervous system gray matter vs. white matterGray matter- mostly cell bodies of neuroglia cells and neuronsSynaptic terminals, unmyelinated CNS interneuronsRegions: dorsal horn, lateral horn, ventral hornCentral canal at center contains cerebrospinal fluidWhite matter- mostly myelinated axons (nerve fibers) of neuronsRegions: various named ascending tracts and descending tractsCerebral cortex, Thalamus, Hypothalamus, and BrainstemThe four lobesFrontal lobeVoluntary motor activitySpeechIntegrative thinkingParietal lobeSomatosensory information processing and perceptionSpatial perceptionFacilitates cross-talk and integrative processing among other 3 lobesTemporal lobeAuditory information processing and perceptionOccipital lobeVisual information processing and perceptionCerebellum- maintain balance & posture, enhance muscle tone, coordinate planning of skilled voluntary muscle activityAmount of motor control is proportional to the amount of grey matter in the primary motor cortex of the frontal lobeAmount of sensory perception is proportional to the amount of grey matter in the primary somatosensory cortex of the parietal lobeThalamusVery deep brain structureBilateral- left side & right sideForms lateral walls of 3rd ventricleFunctions:Crude awareness of sensationSynaptic relay station for all sensory input en route to cerebral cortexSome degree of consciousnessA role in motor control by virtue of connections to frontal lobe, basal nuclei, cerebellumHypothalamusInferior-anterior to thalamus; superior to pituitary glandReceives inputs from thalamus and brainstemFunctions:Controls:Body temperatureThirst driveUrine outputFood intakeAnterior pituitary gland hormone secretionUterine contractionsMilk ejectionReleases posterior pituitary hormones DIRECTLY INTO BLOODEx. Hypothalamus releases the posterior pituitary gland hormone oxytocin, which goes to the uterus & cervix and causes contraction/dilationParticipates in regulation of:Sleep-wake cyclesEmotionsInstinctual and learned behavioral patternsIs a coordination center for the autonomic nervous system which controls smooth muscle cells, cardiac muscle cells, and gland cells all over the bodyBrainstem functionsLocation of CONTROL AND REGULATION CENTERS for CARDIOVASCULAR, respiratory, and digestive body systemsRegulates muscle function with cerebellum involved with equilibrium and postureInvolved with arousal and activation of cerebral cortexRole in regulating sleep-wake cyclesThe spinal cordSpinal cord-Continuation of brainstem from base of skull in vertebral column ending a few inches below your rib cageYour spinal cord is about the diameter of your thumbDivided into 5 unequal segments: CTLSCCervicalThoracicLumbarSacral (like sacred)Coccygyeal31 pairs of spinal nerves attach to spinal cordRecall that a nerve is not a neuronThere are 31 pairs of spinal nervesThere are 12 pairs of cranial nervesGrey matter and white matter:Dorsal horn- cell bodies of interneurons on which afferent neurons terminate (Posterior)Lateral horn- cell bodies of automatic efferent nerve fibersVentral horn- cell bodies of somatic efferent neuronsGo to skeletal m.AnteriorTract- bundle of CNS interneurons that share common origin and destinationAscending tracts- carry nerve impulses through the spinal cord and project to many brain centersEx. Ventral spinocerebellar tractMuscle stretch, velocityDorsal column tractTouch, pressure, vibrationLateral spinothalamic tractPain, temperatureDescending tracts- carry nerve impulses from higher brain centers or the brain stem to gray matter in the spinal cordEx. Lateral corticospinal tractVoluntary control of skeletal muscleVentral corticopsinal tractVoluntary control of skeletal muscleDorsal columnsConscious muscle sense concerned with awareness of body position; crossed touch, pressure, vibrationVentral spinocerebellarCrossed; unconscious muscle tenseVentral corticospinalUncrossed down spinal cord; crosses at level of termination in spinal cord; voluntary control of musclesLateral spinothalamicCrossed; pain and temperatureLateral corticospinalCrossed; voluntary control of skeletal musclesAmyotriphic laternal sclerosishardening' of neurons in lateral columns of spinal cordprogressive fatal degeneration of motor neurons in the cerebral cortex and lateral corticospinal tractseventual loss of motor controlSpinal reflexes-A reflex- any response that occurs automatically WITHOUT constant input or regulation by the cerebral cortexalthough the cerebral cortex may perceive the reflex after the fact, the reflex sensation, integration, and motor output (i.e. input → processing → output) is ENTIRELY handled at specific levels in the spinal cord.a REFLEX ARC is the specific neuroanatomical pathway required to bring about a reflex response.spinal reflexes (e.g. tendon reflexes) are common diagnostic procedures used by clinicians to evaluate the structural and functional integrity of peripheral nerves to/from selected spinal cord segments.can be elicited by tapping