Central Nervous System PDF

CENTRAL NERVOUS SYSTEM Brain Receives and processes sensory information, initiates Cerebrum responses, stores memories, generates thoughts and emotions ◦Left and right hemisphere Medulla Oblongata...

CENTRAL NERVOUS SYSTEM Brain Receives and processes sensory information, initiates Cerebrum responses, stores memories, generates thoughts and emotions ◦Left and right hemisphere Medulla Oblongata ◦Functions: conscious experience of sensation ◦Crucial for life and initiation of voluntary movement ◦Regulates heart rate, blood pressure, breathing, walking, ‣ Extensively folded sleeping, swallowing ‣ Gyrus = outward fold Pons ‣ Sulcus = inward fold ◦Influences cortex to maintain consciousness and alertness ‣ Fissure = deep sulcus ◦Regulation of posture, locomotion, and visceral function ◦Structure ◦Provides pathway for nerve fibers to relay sensory ‣ Cerebral cortex = mapped according to information cerebellum cerebral cortex function Midbrain ‣ White matter = myelinated axons ◦Location of the BRAINSTEM UMN PATHWAYS cerebrum Projection fibers = leave white ◦Subconscious posture and voluntary skilled/learned matter and terminate in basal nuclei, É movements brainstem, or spinal cord Cerebellum EÉÉÉÉ i mm◦Originate in thalamus and terminate in cerebral cortex thalamus ◦Helps synchronizing muscle activity and controlling hypothalamus midbrainpons medulla oblongata equilibrium and eye movement Association fibers = connects ◦Intimate contact with cerebral cortex, brainstem, spinal regions of cerebral cortex within cord ONE hemisphere ◦Capable of assessing disparities between intended motor Commissural fibers = connects action and muscular response vortices from R to L ◦Sensory information from skin, joints, muscle, vestibular ‣ Basal Nuclei = cluster of neuron cell system, visual system bodies graymatter Thalamus and Hypothalamus Project output via the thalamus into ◦Thalamus = large nucleus that extends into each the supplementary and premotor hemisphere orvreeerstoitastnemailman cortices ‣ KEY STRUCTURE that preprocesses most Also send output directly to information reaching cerebral cortex brainstem ◦Hypothalamus = center of homeostasis Inhibitory output - when this stops ‣ Fighting, fleeing, feeding, sex working a motor system become ‣ Coordinates adenohypophysis, heart rate, blood active that is not supposed to pressure, body temp, water balance, food intake, circadian rhythm, gonadal function, and emotions ‣ Secretes = GnRH, TRH, CRH, GHRH, PTH, somatostatin  Cerebral Cortex 6 separate horizontal layers parallel to surface of cortex Different columns organized into functional areas raga lobe occipital Primary cortical sensory areas = areas that receive area say i sensory signals from CNS premotor ◦Parietal Lobe = somatic sensory area; pain processing ◦Temporal Lobe = auditory + vestibular area olfactory bulb ◦Frontal Lobe = primary motor and premotor cortex ◦Occipital Lobe = visual interpretation Spinal Cord ◦Olfactory = olfactory bulb; sense of smell Protected by vertebral column Motor cortex = gives rise to PYRAMIDAL TRACT Transverse section of spinal cord is tubular with a ◦Primary motor area = muscle activation small central canal filled with CSF ◦Premotor frontal cortex: plan and organize the OUTSIDE = white matter sequence of movement oppositeofthebrain INSIDE = gray matter ◦Supplementary motor cortex: preparatory Sensory signal travels to 2 separate destinations orientation of the body to execute a particular motor ◦Gray matter or higher levels task Sensory info enters cord DORSALLY Association areas = learning and intelligent behavior Motor info enters cord VENTRALLY ◦Integration and interpretation of information ◦Integrate sensory inputs, memory, and behavior centers to produce a specific learned output SPINAL NERVES 36 PAIRS Communicate the spinal cord with sensory receptors, i i muscles, viscera, and vessels cervical in tumescence i coay Each segment gives rise to paired spinal nerves Exit vertebral canal via the lateral vertebral foramen of thei atlas or via intervertebral foramen Neurons innervating the limbs are confined to cervical and lumbar INTUMESCENCES Fibers: Structure: IIa i man afferent efferent i.i ◦Somatic sensory = enter DORSAL root ii e ◦Root = dorsal and ventral ion i.s ◦Visceral sensory = enter DORSAL root ◦Main trunk ◦Somatic motor = exit VENTRAL root ‣ Gives off dorsal communicating branch —> ◦Visceral motor = exit VENTRAL root sympathetic trunk ◦Peripheral branches  PERIPHERAL NERVOUS SYSTEM Sensory/Afferent Motor/Efferent Brings information to the CNS from receptors in Carries motor commands from CNS to peripheral peripheral tissues and organs tissue and systems Visceral Sensory: provides information about internal Somatic Motor: controls skeletal muscle organs (visceral receptors + sensory neurons) contraction (voluntary control) Somatic Sensory: provides information about Visceral Motor: provides autonomic regulation of position, touch, pressure, pain, and temperature smooth muscle, cardiac muscle, glands and (somatic receptors + sensory neurons) adipose tissue (involuntary control) Receptors ◦Sympathetic = fight or flight ◦Axon project via cranial and spinal nerves into ◦Parasympathetic = rest or digest CNS Neurons ◦Make connections with local circulatory for reflex ◦Upper Motor Neuron = completely functions or travel in cord to specific areas of this c oncept contained inside CNS brain back comes ◦Lower Motor Neuron = cell body in CNS ◦Free Nerve Endings: unmyelinated axons and axons in PNS ◦Complex Receptors: enclosed nerve ending with layers of connective tissue to feel pressure ◦Special Senses Receptors: receptors with hair in auditory/vestibular system CRANIAL NERVES Neurons 12 PAIRS ◦Primary (first-order) = receive signal and send receptor stoner Most arrive in the brainstem information to CNS Individual nerves have specific spinaicora orbrainstem ◦Secondary (second-order) = conduct impulses order and sensory and/or motor, somatic from spinal cord to brainstem to thalamus and/or autonomic functions thalamus ‣ Cross over to opposite side before reaching sraorder a somatosensory cortex Useful to group by function thalamus nutnorder withinas ◦Tertiary (third-order) = conduct impulses from thalamus to primary somatosensory cortex ◦Quaternary (fourth-order) = located in sensory area of cerebral cortex