L13 NPB 101 - Lecture 13 •  SmartSite: – ...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Lecture 13 •  SmartSite: –  Lecture 13 Notes •  Review –  Autonomic Nervous System •  Announcements: –  None •  Motor Control I –  Organiza<on –  Reflex –  Spinal Control •  Reading (Recommended): –  Relevant por<ons of Chapters 5, 7 & 8 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 (Muscles grouped in antagonis0c pairs) 19 Cross ­Extensor & Withdrawal Reflexes Fig. 5 ­32, pg. 179 20 ...
View Full Document

Ask a homework question - tutors are online