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17 Cards in this Set
- Front
- Back
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Central Nervous System - (CNS) consists of the brain and spinal cord. - processes and stores sensory information and allows us to be sentient being. - connects to the world via the peripheral nervous system - |
Peripheral Nervous System = includes 12 pairs of cranial nerves, 31 pairs of spinal nerves, all sensory nerves, and the sympathetic and parasympathetic nervous systems. Ganglia, sensory neurons, neuromuscular junctions |
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The somatic or motor nervous system regulates voluntary (meaning via CNS input) and considerable involuntary muscle control. |
Autonomic nervous system, - comprised of sympathetic and parasympathetic nerves - which regulates some involuntary muscle movements and the action of glands so we don’t have to think about glandular secretions. |
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Neuron basic functional and structural unit of the nervous system - receives impulses (which are somewhat electrical) through dendrites - The impulse passes along the dendrites, through the cell body, to the axon - myelin sheath is the fatty tissue that covers the axon (neurolemma is a membranous sheath outside of the myelin sheath.) |
Brain - communication and control center of body - receives, processes and evaluates many kinds of input, decides on response or action be taken, and then initiates response - Initiates response - Involuntary actions: = To maintain homeostasis and Regulated by the autonomic nervous system (ANS) - Voluntary actions - Reflex activities |
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Protection for the Brain - protected by rigid bone of skull, three membranes (meninges) and Cerebral Spinal Fluid (CSF) - cranial and facial bone connected by sutures (immovable joints consisting of fibrous tissue) - contains cavities (fossae) and foramina (openings) and canals where nerves and blood vessels pass |
Protection for Brain (3 Meninges) CT membranes covering brain and spinal cord 1. Dura mater: Outer layer- tough, firbous, double-layered memrbane (collect venous blood and CSF for return to general circulation) (closest to the bone) 2. Subdural space: beneath dura, potential space (normally empty or blood fill after injury) 3. Arachnoid: Middle layer (loose, web-like covering) 4. Subarachnoid space: - Contains CSF, cerebral arteries, veins. 5. Pia mater: Adheres to the surface of the brain (inner layer) contain many small blood vessels (delicate) |
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Arachnoid villi - projections of arachnoid into dural sinuses at several places around brain - CSF can be absorbed into venous blood |
CSF - Provides cushion for brain and spinal cord - Similar to plasma in appearance: clear liquid (Different electrolyte, glucose, protein concentrations) - Change in characteristics of CSF is diagnostic tool - Formed constantly in choroid plexuses of the ventricles - Flows though ventricles into subarachnoid space - Equal amounts of CSF need to be produced and reabsorbed at same rate to maintain intracranial pressure (ICP) |
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Blood-Brain Barrier - protective mechanism provided primarily by impermeable capillaries in brain (located in capillaries) - limits the passage of potentially damaging materials into the brain - controls the delicate but essential balance of electrolytes, glucose, and proteins in the brain - Lipid-soluble substances can easily pass. - Poorly developed in neonates |
Blood-CSF barrier - Located at the choroid plexus - Controls constituents of CSF |
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TA 14-1 b) explain effect of production of more CSF than can be reabsorbed = exerts increased pressure on the brain, spinal cord, and blood vessels. |
Functional Areas: Cerebral Hemispheres - make up the largest and most obvious portions of brain - Longitudinal fissure separates two hemispheres - outer surface covered by elevations or gyri (gyrus singular) separated by grooves or sulci (sulcus singular) |
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Functional Areas: Cerebral Hemispheres Cortex = “Gray matter”——nerve cell bodies Corpus callosum = “White matter”—myelinated nerve bundles (tracts) - connect the hemispheres Each hemisphere has 5 major lobes (or 4) - Right hemisphere and left hemisphere are similar in structure but not function Prefrontal, frontal, parietal, temporal, and occipital lobes |
Each hemisphere concerned with voluntary movement and sensory function in opposite (contralateral) side of body *large # of nerve cells required to innervate face compared with amount of cortex allocated to trunk |
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Crossover of most of these tracts occurs in medulla, damage to motor cortex in left frontal lobe adjacent to longitudinal fissure (top of head) = results in paralysis (paresis) of muscle of right leg |
Each special sensory area of cortex has = association area (surrounding primary cortex - sensory input is recognized and interpreted. Right and left hemispheres similar in structure, not necessarily in function |
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Dominant hemisphere = side of brain that controls language (most people is in left hemisphere) - Two special areas involved language skills - Broca's Area: the motor or expressive speech area (output of words, verbal and written) coordinated in appropriate and understandable way - Wernicke's Area: integration center that comprehends language received (spoken and written) located in posterior temporal lobe |
Prefrontal Cortex (anterior to motor and premotor cortex) - Coordinates complex cognitive behavior - Components for expression of personality - social relationships and impulse control |
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Basal nuclei (Basal Ganglia) - clusters of cell bodies (gray matter) - Part of the extrapyramidal system (EPS) - Control and coordination of skeletal muscle activity: prevent excessive movements and initiating accessory and often involuntary actions (arm-swinging when walking) - Two additional nuclei located in midbrain (substantia nigra and red nucleus) connected to basal nuclei and the EPS |
Limbic system - Consists of many nuclei and connecting fibers (Cerebral Hemisphere) - Responsible for emotional reactions or feelings (many connections to all areas of brain) - involved with part of hypothalamus - any cognitive (intellectual) decision arise from higher cortical centers |
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Diencephalon: - Central portion of the brain - contains the thalamus, the hypothalamus, and the epithalamus - Thalamus: consists of many nerve cell bodies: major function to serve as sorting and relay station for incoming sensory impulses. |
Diencephalon: Cont'd - Hypothalamus: maintain homeostasis, control ANS, and much of endocrine system thru hypophysis or pituitary gland - responsible for regulation of body temp, intake of food and fluid and regulation of sleep cycles - key to stress response and major role in emotional responses thru limbic system - biologic behaviors (sex drive - libido) |
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Brain Stem - inferior portion of brain: connecting link to spinal cord - contains Reticular Formation - Pons: - Bundles of afferent and efferent fibers - Several nuclei of cranial nerves Medulla oblongata (vital control center) - Control center for respiratory and cardiovascular function - Coordination of cough reflex, swallowing, vomiting - Nuclei for several cranial nerves– Cranial nerves 12 pairs, originate from the brain stem and pass through the foramina in the skull to serve structures in the head and neck |
Cerebellum - located dorsal to the pons and medulla, below the occipital lobe - Functions to coordinate movement and maintain posture and equilibrium (by adjusting Input from the pyramidal system) - Receives input from proprioceptors in muscles and joints - Receives input from visual and vestibular pathways |
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Brain Stem Cont'd = Contains the reticular formation which is a network of nuclei and neurons - part of Reticular formation, reticular-activating system RAS that determines degree of arousal or awareness of cerebral cortex - Drugs can affect the activity of the RAS—increasing or decreasing input to cerebral cortex and diencephalon |
TA 14-2 Somatosensory area—cortex of the parietal lobes (postcentral gyrus); it receives, comprehends, and identifies source of general sensory input. RAS refers to groups of neurons in the brainstem that determine the level of awareness of the brain to incoming stimuli. The prefrontal area is responsible for intellectual function and personality. Wernicke’s area is located primarily in the left posterior temporal lobe; it is responsible for the comprehension of written and spoken language. Basal nuclei are groups of nerve cell bodies deep in the cerebral hemispheres; they coordinate and refine movements. Visual association area—surrounds the primary visual cortex in the occipital lobe; it functions to interpret visual stimuli. |
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TA 14-2 White matter is made up of myelinated nerve fibers (axons or dendrites), collected into bundles or tracts, that conduct impulses between areas of the brain or between the brain and spinal cord (e.g., corpus callosum or spinothalamic tract). |
TA 14-2 Brain damage in the prefrontal cortex would result in loss in the coordinating complex cognitive behavior, personality changes, and breakdown of impulse control and may affect social relationships. Left frontal lobe damage would result in loss of voluntary movement or paralysis on the right side of the body, loss of intellectual function and problem-solving ability, change in personality, and impaired ability to communicate verbally or in writing. Cerebellum damage would mean a loss of balance and equilibrium, coordination, and control of fine movements. Hypothalamus damage would result in impaired control of ANS, endocrine dysfunction, fluid imbalance, change in appetite, and loss of stress response. |
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Blood Supply to the Brain - by Internal carotid and vertebral arteries - (at base of brain) Each internal carotid artery divides into an anterior and a middle cerebral artery. - Anterior cerebral artery = Supplies the frontal lobe - Middle cerebral artery = Supplies the lateral part of the cerebral hemispheres Posteriorly - Basilar artery (Formed by vertebral arteries) |
Blood Supply to the Brain Base of Brain- basilar artery divides into - right and left posterior cerebral arteries (supply blood to occipital lobes) Anastomoses - Anterior communicating artery (between anterior cerebral arteries) - Posterior communicating arteries (between middle cerebral and posterior cerebral arteries) |
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Blood flow in cerebral arteries is relatively constant - brain cells constantly use oxygen and glucose (nutrients) and have little storage capacity. Autoregulation - mechanism by which increased carbon dioxide levels or decreased pH in blood, or decreased blood pressure in area of brain results in = immediate local vasodilation |
Pressoreceptors (baroreceptors) and chemoreceptors protect brain from damage related to abnormal blood pressure or pH level in systemic flow |
