Handouts Of Nervous System Ana Physio

Handouts of Nervous System USJR-COLLEGE OF NURSING Review Anatomy and Physiology Functions In coordination with the endocrine system, provides means by which cell and tissue functions are integrated into a solitary, surviving organism Controls skeletal muscle movement ad helps to regulate cardiac and visceral smooth muscle activity Enables reception, integration, and perception of sensory information Provides means necessary for intelligence, anticipation, and judgment Facilitates adjustment to an ever changing external environment Neuron Structural and functional units of the nervous system Consists of cell body, dendrites, axon Cell body : enlarged portion of the neuron Contains well-defined nucleus and nucleolus and Nissl bodies composed of rough endoplasmic reticulum Nuclei – cluster of cell bodies within the CNS Ganglia – cluster of cell bodies within the PNS Neuron Classifications According to function based on the direction in which they conduct impulses Sensory (afferent) - conduct impulses from the receptors into the CNS Motor (efferent) – conduct impulses from the CNS to effector organs (muscle and glands) Association or interneurons – located entirely within the CNS serve the integrative and associative functions of the nervous Neuron Dendrites: thin branched processes that extend from the cytoplasm of the cell body Serve as a receptive area for stimuli Transmit electrical impulses to the cell body Axon: process that conducts impulses away from the cell body Frequently referred to as nerve fibers Neuron Axon Myelin sheath – composed of successive wrappings of the cell membrane Serve to increase the velocity of nerve impulse conduction in axons Myelinated axons – white matter Myelin – has a high lipid content giving it a white color hence the name white matter Node of Ranvier – (after Louis Ranvier, French pathologist) also known as neurofibril node, gap in the myelin sheath which increase conduction of nerve impulses by allowing impulses to jump from node to node Sheath of Schwann (neurilemomma or neurilemmal sheath) – a living sheath of Schwann cytoplasm that surround an axon and its myelin sheath Cell bodies – gray matter

Neuroglia Also known as Glial cells or Supporting cells of the nervous system Protect and aid the function of the neurons Neuroglia Types of Cells Schwan cells or neurolemmocytes – form the myelin sheaths around axons of the PNS Oligodendrocytes or oligodedroglia – form myelin sheaths around axons of the CNS Microglia – phagocytize foreign and degenerated material Astrocytes – help regulate passage of molecules from blood to the brain “Bloodbrain barrier” Ependymal cells – aid in movement of fluid within the CNS, “CSF-brain barrier” or blood-CSF barrier” Ganglionic cells (satellite cells) – support neuron cell bodies within the ganglia of the PNS

CNS Brain Three Divisions/ Regions Forebrain – cerebrum, limbic system, basal ganglia Midbrain –corpora quadrigemina, tegmentum, cerebral peduncles Hindbrain – medulla oblongata, pons, cerebellum •

Cerebrum –

concerned with higher brain functions such as perception of sensory impulses, instigation of voluntary movement, storage of memory, thought processes and reasoning ability, also concerned with instinctual and emotional functions

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Consists of five paired lobes within two hemispheres

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Largest and most obvious portion of the brain

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Accounts for 80% of brain mass

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Cerebral Hemispheres

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Left – controls analytical and verbal skills: reading, writing, and mathematics

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Right – spatial and artistic kinds of intelligence

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Corpus callosum – connect the two hemispheres internally, permits sharing of learning and memory between two hemispheres

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Cerebrum

Two layers •

Cerebral cortex – composed of gray matter

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Cerebral medulla (Cerebrum) – composed of thick white matter

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Convolutions – numerous folds and grooves which characterized the cortex –

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Triple the area of gray matter •

Gyrus (gyri) – elevated folds

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Sulcus (sulci) depressed grooves

Cerebrum

Lobes •

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Frontal Lobe –anterior portion, separated by the central sulcus from the parietal lobe; lateral sulcus separates lobes from temporal lobe –

Precental gyrus is the primary motor cortex involve with control of voluntary muscles

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Functions include initiating voluntary motor impulses of skeletal muscles, analyzing sensory experiences, provides reponses relative to personality

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Mediate responses related to memory, emotions, reasoning, judgment, planning, and speaking

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Broca’s area (motor speech area)

Cerebrum

Lobes •

Parietal Lobe- lies behind the recentral gyrus and above the lateral sulcus

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Primary somatosensory cortex – (Postcentral gyrus) receives sensory information from the thalamus

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Postcentral gyrus is also called somatoesthetic area since it responds to stimuli from cutaneous and muscular receptors throughout the body

Cerebrum

Lobes •

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Temporal lobe – lies below the lateral sulcus and merges with the parietal and occipital lobe –

Contains auditory centers that receive sensory neurons from the cochlea of the ear

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Wernicke’s area – responsible for reception and interpretation of speech

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Involved in long-term memory, balance, taste, and smell

Cerebrum

Lobes •

Occipital lobe – lies posterior to the temporal and parietal lobes –

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Primary visual cortex (visual receptive area), visual association area

Cerebrum

Lobes •

Insula- fifth lobe, deep portion of the cerebrum –

Integrates other cerebral activities and may have some function in memory

Basal Ganglia/Nuclei Paired masses of gray matter located deep within the white matter of the cerebrum Control unconscious contractions of skeletal muscles such as those of upper limbs like arm swinging during walking and running Adds gracefulness to UMN-controlled manipulative movements Works together with the premotor and supplementary motor cortex, and parts of the thalamus to provide associated movements that accompany highly skilled behavior Part of the extrapyramidal system L

imbic System Also known as the emotional brain Composed of structures surrounding the corpus callosum and diencephalon Involved with primary behavioral responses, visceral reaction to emotion, feeding behaviors, biologic rhythm and sense of smell Expression of affect (emotional and behavioral statesz0

Thalamus Large oval mass of gray matter Acts as a relay center for all sensory impulses except smell to the cerebral cortex Responds to general sensory stimuli and crude awareness Acts as relay center for critical information regarding motor activities ti and from the motor cortex Hypothalamus Located below the thalamus, forms the floor and part of lateral wall of third ventricle Functions: Cardiovascular regulations: control of heart beat and BP Body Temperature regulation Regulation of water and electrolyte balance: ADH, and Thirst center Regulation of hunger and control of GI activity: Feeding center; satiety center Regulation of sleeping and wakefulness: sleep and wake centers Sexual response: sexual center respond to tactile stimulation of genital organ; orgasm Emotions such as anger, fear, pain, and pleasure Control of endocrine functions Epithalamus Posterior portion of diencephalon including the thin roof over the third ventricle Pineal gland or pineal body: thought to have neuro-endocrine functions Subthalamus Flanks the hypothalamus laterally Serves as an important extrapyramidal center for motor activities Pituitary Gland Also called hypophysis, rounded, pea-shaped positioned inferiorly in the diencephalon Anterior (adenophysis)

Posterior(neurophysis)

Midbrain Composed of the corpora quadrigemina (superior and inferior colliculi) Superior colliculi: involved with voluntary and involuntary motor movements Inferior colliculi: involved with movements affecting the auditory system such as positioning of head to improve hearing Tegmentum (Red nucleus and substantia negra) Substantia negra synthesizes DOPAMINE Cerebral peduncles: consist of efferent fibers of the corticospinal tract

Hindbrain Medulla Oblongata Forms lowest portion of brains stem Controls reflex activity such as coughing, sneezing, swallowing, and vomiting Nuclei of CNs IX and XII are located in this region Point at which major descending motor pathways (corticospinal tracts) cross to the other side, decussate Reticular Activating System Cardiac center Vasomotor center Respiratory center Pons Also called as bridge Transmission of information from cerebellum to the brainstem and between two cerebellar hemispheres Respiratory centers Apneustic and pneumotaxic centers Nuclei of fifth through eight CNs originate in this structure Cerebellum Also known as the “little brain” Functions to coordinate skeletal muscle contractions, reflexive involuntary finetuning of motor control and for maintaining balance and posture Ventricles of the Brain Ventricles composed of the lateral (first and second), third, and fourth; central canal; and subarachnoid space contain cerebrospinal fluid (CSF) CSF is formed in the Choroid plexuses from blood plasma CSF is a clear, lymphlike fluid that serves as a protective cushionaround and within the CNS Spinal Cord

Portion of the CNS that lies within the vertebral canal and is surrounded and protected by the vertebral column Functions as a large nerve cable that connects the brain and the body Impulse conduction Reflex Integration