Transcript Chapter 14
Anatomy and Physiology, Sixth Edition Rod R. Seeley Idaho State University Trent D. Stephens Idaho State University Philip Tate Phoenix College Chapter 14 Lecture Outline* *See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes. 14-1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 14 Integration of Nervous System Functions 14-2 Sensation • Senses: Means by which brain receives information about environment and body – General: Distributed over large part of body • Somatic: Touch, pressure, temperature, proprioception, pain • Visceral: Internal organs and consist mostly of pain and pressure – Special senses: Smell, taste, sight, hearing, balance • Sensation or perception: Conscious awareness of stimuli received by sensory receptors 14-3 Types of Sensory Receptors • Mechanoreceptors: Compression, bending, stretching of cells • Chemoreceptors: Smell and taste • Thermoreceptors: Temperature • Photoreceptors: Light as vision • Nociceptors: Pain • Exteroreceptors: Associated with skin • Visceroreceptors: Associated with organs • Proprioceptors: Associated with joints, tendons 14-4 Sensory Nerve Endings • • • • • • • • Free nerve endings: Cold receptors and warm Merkel’s disk: Light touch, superficial pressure Hair follicle receptor: Light touch, bending of hair Pacinian corpuscle: Deep cutaneous pressure, vibration and proprioception Meissner’s corpuscle: Two-point discrimination Ruffini’s end organ: Continuous touch or pressure Muscle spindle: Proprioception as to muscle stretch and control of muscle tone Golgi tendon organ: Important in muscle contraction and tendon stretch proprioception 14-5 Sensory Nerve Endings in Skin 14-6 Two-Point Discrimination 14-7 Muscle Spindle and Golgi Tendon Organ 14-8 Responses of Sensory Receptors • Receptor: Interaction of stimulus with sensory receptor produces a local potential – Primary: Have axons that conduct action potential in response to receptor potential – Secondary: Have no axons and receptor potentials produced do not result in action potentials but cause release of neurotransmitters • Accommodation or adaptation: Decreased sensitivity to a continued stimulus • Proprioceptors – Tonic: Example is know where little finger is without looking – Phasic: Example is you know where hand is as it moves 14-9 Sensory Nerve Tracts • Transmit action potentials from periphery to brain • Each pathway involved with specific modalities • First half of word indicates origin, second half indicates termination 14-10 Spinothalamic System • Conveys cutaneous sensory information to brain • Unable to localize source of stimulus • Divisions – Lateral for pain and temperature – Anterior for light touch, pressure, tickle, itch 14-11 Dorsal-Column/ Medial-Lemniscal System • Carries sensations of – Two-point discrimination – Proprioception – Pressure – Vibration • Tracts – Fasciculus gracilis – Fasciculus cuneatus 14-12 Spinocerebellar System • Carry proprioceptive information to cerebellum • Actual movements can be monitored and compared to cerebral information representing intended movement • Tracts – Posterior – Anterior 14-13 Sensory Areas of Cerebral Cortex 14-14 Pain • Types – Referred: Sensation in one region of body that is not source of stimulus – Phantom: Occurs in people who have appendage amputated or structure removed as tooth – Chronic: Not a response to immediate direct tissue injury 14-15 Somatic Sensory Cortex 14-16 Primary Motor Cortex 14-17 Descending Spinal Pathways • Direct – Control muscle tone and conscious skilled movements – Direct synapse of upper motor neurons of cerebral cortex with lower motor neurons in brainstem or spinal cord – Tracts • Corticospinal • Lateral • Anterior corticobulbar 14-18 Descending Spinal Pathways • Indirect – Synapse in some intermediate nucleus rather than directly with lower motor neurons – Tracts • Rubrospinal • Vestibulospinal • Reticulospinal 14-19 Cerebellar Comparator Function 14-20 Speech • Speech area normally in left cerebral cortex – Wernicke’s area: Sensory speech – Broca’s area: Motor speech • Aphasia: Absent or defective speech or language comprehension 14-21 Brain Waves and Sleep • Electroencephalogram (EEG): Record of brain’s electrical activity • Brain wave patterns – Alpha: Resting state with eyes closed – Beta: During intense mental activity – Theta: Occur in children but also in adults experiencing frustration or brain disorders – Delta: Occur in deep sleep, infancy, and severe brain disorders 14-22 Memory • Sensory – Very short-term retention of sensory input • Short-term – Information retained for few seconds to minutes • Long-term – Explicit or declarative • Retention of facts • Accessed by hippocampus and amygdaloid (emotional) – Implicit or procedural • Development of skills as riding a bicycle 14-23 Long-Term Potentiation 14-24 General CNS Disorders • Infections – Encephalitis: Inflammation of the brain – Rabies: Viral disease transmitted by bite of infected animal – Multiple sclerosis: Possibly involves autoimmune response to viral infection • Other disorders – Stroke: CVA or cerebrovascular accident caused by hemorrhage, thrombosis, embolism – Aneurysm: Dilation or ballooning of an artery – Alzheimer’s disease: Severe type of dementia – Epilepsy: Group of brain disorders that have seizures 14-25 Effects of Aging on Nervous System • Gradual decline in sensory and motor function • Reflexes slow • Size and weight of brain decrease – Decreased short-term memory in most people – Long-term memory unaffected or improved 14-26