Lecture_13 - Lecture 13 •  SmartSite: • ...

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Unformatted text preview: Lecture 13 •  SmartSite: •  Announcements: –  Midterm 1: –  Lecture 13 Notes •  Review •  25 MC ques:ons •  Covers lectures through Friday (Star:ng Mon, lectures on Midterm 2) •  Requires students to bring and use SCANTRON 2000 (blue) •  Will be in 2 rooms –  3 Keiber (Last Name A ­G) –  123 Sci Lec (Last Name H ­Z) •  Motor Control I –  Organiza:on –  Reflex –  Spinal Control –  Visual System –  Autonomic Nervous System •  Reading (Recommended): –  Relevant por:ons of Chapters 5, 7 & 8 REV: Autonomic Nervous System •  Extends from CNS to an innervated organ •  Two ­neuron chain •  Two subdivisions –  Preganglionic fiber –  Postganglionic fiber •  Most visceral organs innervated by both SNS & PNS fibers –  Sympathe:c nervous system (SNS) –  Parasympathe:c nervous system (PNS) –  Generally produce opposite effects in a par:cular organ –  Dual innerva:on SNS & PNS allows precise control REV: Effects of ANS on Various Organs Table 7 ­3, pg. 242 Motor System I – Organiza:on & Spinal Reflex PNS Soma:c Nervous System •  Consists of axons of motor neurons that originate in spinal cord or brain stem and terminate on skeletal muscle •  Motor neuron releases neurotransmicer, Ach, which s:mulates muscle contrac:on •  Motor neurons are final common pathway by which various regions of CNS exert control over skeletal muscle ac:vity –  These areas of CNS include spinal cord, motor regions of cortex, basal nuclei, cerebellum, and brain stem Motor System Organiza:on Afferent Sensory (Receptor) P N S Integra:on CNS P N S Motor (Muscle) Efferent Fig. 5 ­12, pg. 142 Levels of Organiza:on •  Motor Output can be: –  Voluntary (walking, standing, talking, etc) –  Involuntary (heart beat, breathing, etc) [ANS] –  We will focus on voluntary •  Motor responses range from: –  SIMPLE •  Reflex (automa:c, involuntary and spinal control) –  COMPLEX •  Voluntary movement Reflex •  A stereotyped response to a fixed s:mulus •  5 typical elements STIMULUS Sensor Afferent Path Integra0on Efferent Path Effector RESPONSE Basic Reflex Anatomy 1 Sensor 2 Afferent Path 3 Integra0on 4 Efferent Path 5 Effector Receptors •  Receptors –  Muscle Spindle (length) –  Golgi Tendon Organ (tension/force) –  Joint Receptor (posi:on) •  Muscle fiber types –  Extrafusal (force) –  Intrafusal (sensory) Golgi Tendon Organ Muscle Body & Muscle Spindle Tendon Whole Muscle Muscle Spindle Structure •  Consist of collec:ons of specialized muscle fibers known as intrafusal fibers –  Lie within spindle ­shaped connec:ve :ssue capsules parallel to extrafusal fibers –  Each spindle has its own private efferent and afferent nerve supply –  Play key role in stretch reflex Muscle Spindle Fig. 8 ­24a, pg. 287 Muscle Spindle Func:on Primary Afferents Gamma MN Alpha MN Fig. 8 ­25a, pg. 288 Stretch Reflex (monosynap:c) •  Primary purpose is to resist tendency for passive stretch of extensor muscles by gravita:onal forces when person is standing upright •  Classic example is patellar tendon, or knee ­ jerk reflex Patellar Tendon (Stretch) Reflex Fig. 8 ­26, pg. 289 Muscle Spindle Sensi:vity Fig. 8 ­25bcd, pg. 288 Golgi Tendon Organ Fig. 8 ­24b, pg. 287 Inverse Stretch Reflex (polysynap:c) Golgi Tendon Organ Withdrawal Reflex (polysynap:c) Fig. 5 ­31, pg. 178 Reciprocal or Antagonis0c Inhibi0on (Muscles grouped in antagonis0c pairs) Cross ­Extensor & Withdrawal Reflexes Fig. 5 ­32, pg. 179 ...
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