Unformatted text preview: Lecture 13 SmartSite: Lecture 13 Notes Review Visual System Autonomic Nervous System Announcements: None Reading (Recommended): Relevant por<ons of Chapters 5, 7 & 8 Motor Control I Organiza<on Reflex Spinal Control 1 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 2 Effects of ANS on Various Organs Table 7-3, pg. 242 3 Motor System I Organiza<on & Spinal Reflex 4 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 neurotransmi\er, 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 5 Motor System Organiza<on Afferent Sensory (Receptor) P N S Integra<on CNS P N S Motor (Muscle) Efferent Fig. 5-12, pg. 142 6 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 7 Reflex A stereotyped response to a fixed s<mulus 5 typical elements STIMULUS Sensor Afferent Path Integra0on Efferent Path Effector RESPONSE 8 Basic Reflex Anatomy 1 Sensor 2 Afferent Path 3 Integra0on 4 Efferent Path 5 Effector 9 Receptors Receptors Muscle Spindle (length) Whole Golgi Tendon Organ (tension/force) Muscle Joint Receptor (posi<on) Golgi Tendon Muscle fiber types Organ Extrafusal (force) Muscle Body & Muscle Intrafusal (sensory) Spindle Tendon 10 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 11 Muscle Spindle Fig. 8-24a, pg. 287 12 Muscle Spindle Func<on Primary Afferents Gamma MN Alpha MN Fig. 8-25a, pg. 288 13 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 14 Patellar Tendon (Stretch) Reflex Fig. 8-26, pg. 289 15 Muscle Spindle Sensi<vity Fig. 8-25bcd, pg. 288 16 Golgi Tendon Organ Fig. 8-24b, pg. 287 17 Inverse Stretch Reflex (polysynap<c) Golgi Tendon Organ 18 Withdrawal Reflex (polysynap<c) Fig. 5-31, pg. 178 Reciprocal or Antagonis0c Inhibi0on 19 (Muscles grouped in antagonis0c pairs) Cross-Extensor & Withdrawal Reflexes Fig. 5-32, pg. 179 20 ...
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- Spring '08
- stretch reflex, Spindle Tendon