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UA BSC 109 - Nervous System Disorders
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BSC 1069 1st Edition Lecture 17 Outline of Last Lecture I. Nervous system overviewA. Receives information from many sources simultaneously; sorts infoB. Integrates information (processes, compiles, makes sense of this information)C. Extremely fast- can receive, integrate, and respond in tenths of a secondD. Can initiate specific responses such as muscle contraction, glandular secretion, conscious control over movementE. Integrates and controlsII. Nervous system has 2 partsA. Central nervous systemB. Peripheral nervous systemOutline of Current Lecture III. Action Potentials are all-or-none and self-propagatingIV. Neuroglial cells support and protect neuronsV. Information is transferred from a neuron to its targetVI. Neurotransmitters exert excitatory or inhibitory effectsVII. Postsynaptic neurons integrate and process informationVIII. Peripheral nervous system relays information between tissues and CNSIX. Sensory neurons provide information to the CNSX. Disorders of the Nervous systemCurrent LectureXI. Action Potentials are all-or-none and self-propagatingA. The number of action potentials/unit time encodes the strength of the stimulusB. Stronger stimuli generate more action potentials/unit timeC. Speed of action potentials: in larger diameter axons, action potentials travel at greater speedXII. Neuroglial cells support and protect neuronsA. Neuroglial cells make up 80% of nervous system cells1. Support and protection2. Do not transmit action potentials3. Schwann: form myelin sheaths in PNSa) Saves the neuron energyb) Speeds up the transmission of impulsesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.c) Salutatory conduction: leaping pattern of action potential conductiond) Help damaged or severed axons regenerate4. Oligodendrocytes: form myelin sheaths in CNS5. Myelin sheath: wraps around neuron (like insulation) carries nerve impulses faster (myelin is rich in fat, appears glossy white)B. Disorders associated with degeneration of myelin sheaths1. Multiple sclerosisa) A dismantling of the myelin covering of CNS axons by the body’s own immune systemb) Progressive damage to myelin sheaths in brain and spinal cordc) Weakness, visual impairment, incontinence2. Amyotrophic lateral sclerosis or Lou Gehrig’s Diseasea) Progressive damage to myelin sheaths in motor area of spinal cordb) Progressive weakening and wasting of skeletal muscleXIII. Information is transferred from a neuron to its targetA. Targets: another neuron, muscle cell, or glandB. Synapse: special junction between axon terminus and target cellC. Speed of neuron transmission equates speed of reaction/muscle movementXIV. Neurotransmitters exert excitatory or inhibitory effectsA. Response of postsynaptic target cell depends on1. Type of neurotransmitter (>50 types)2. Type of receptors3. Type of gated ion channelsB. Excitatory neurotransmitters help move skeletal muscles with help of ACHC. Inhibitory neurotransmitters help with posture and stretchingXV. Postsynaptic neurons integrate and process informationA. Response in postsynaptic cell depends on1. How many neurons are forming synapses with it2. Whether the neurons forming synapses with it are excitatory or inhibitoryB. Convergence: occurs when one neuron receives input from many othersC. Divergence: occurs when one neuron sends action potentials to multiple other neuronsXVI. Peripheral nervous system relays information between tissues and CNSA. Nerves contain axons of many neurons wrapped together in a protective sheath (nerve/neuron bundle)B. Cranial nerves (12 pairs)C. Spinal nerves (31 pairs)XVII. Sensory neurons provide information to the CNSA. Provide information for both the somatic and autonomic motor divisions of the PNSB. Somatic division controls skeletal muscles1. Voluntary: conscious control of skeletal muscles2. Involuntary (reflexes)a) Spinal reflexes: involuntary responses mediated primarily by spinalcord and spinal nerves, with little brain involvementb) Flexor (withdrawal) reflexc) Crossed extensor reflexd) Stretch reflex: important in maintaining upright posture, movementC. Autonomic division controls automatic body functions1. Part of the motor output of the PNS2. Controls automatic body functions3. Sympathetic a) Prepares the body for emergencyb) Norepinephrine is the key neurotransmitterc) Produces fight-or-flight response(1) Increases heart rate and respiration(2) Raises blood pressure(3) Dilates pupils(4) Slows digestion and urine productiond) Generally produces a unified response in all organs at oncee) Opposes parasympathetic division4. Parasympathetica) Relaxes the bodyb) Opposes sympathetic divisionc) ACH is the key neurotransmitterd) Lowers heart rate and respiratione) Increases digestionf) Permits defecation and urinationD. The brain and spinal cord constitute the CNS1. Bone: skull and vertebrae2. Meninges: protective membranes (meningitis)3. Cerebrospinal fluid: bathes the brain, spinal cord4. Blood-brain barrier: prevents entry of certain chemicals and pathogens5. Spinal cord relays informationa) Spinal cord is a superhighway for action potentials between the brain and the rest of the bodyb) White matter: outer portion of the spinal cordc) Gray matter: center portion of the spinal cord; contains cell bodies, dendrites6. The brain processes and acts on informationa) Hindbrain: coordinates basic, automatic, and vital tasksb) Midbrain: coordinates muscle groups and responses to sight and soundc) Forebrain: receives, integrates sensory input, determines complex behaviord) Brain activity continues during sleep(1) Reticular activating system(2) Group of neurons within the reticular formation(3) Releases serotonin to fall asleep(4) Releases norepinephrine to return to wakefulness7. Psychoactive drugs affect higher brain functionsa) Affect states of consciousness, emotions, or behaviorb) Able to cross blood/brain barrierc) Influence concentrations or actions of neurotransmittersd) Affect higher brain functionse) Psychological dependence: user craves the feeling associated with the drugf) Tolerance: requires more of the substance to achieve the same effectg) Addiction: the need to continue obtaining and using a substance; no free choiceh) Withdrawal: physical symptoms that occur upon stopping the drugXVIII. Disorders of the Nervous systemA. Trauma1. Physical injury to brain or spinal cord2. Concussiona) Blow to the head may lead to


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UA BSC 109 - Nervous System Disorders

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