Lecture 5 Outline of Last Lecture I. Muscle Terminology II. Microscopic Muscle Anatomy III. Muscle Fiber Type IV. Muscle Tissue Properties V. Ty p e s o f M u s c l e C o n t r a c t i o n VI. Role of Muscles VII. Tying Roles of Muscles All Together VIII. Skeletal Muscle Adaptation Outline of Current Lecture I. Neural Control of Voluntary Movement II. CNS III.PNS IV. Neurons V. Neural Control of Voluntary Movement part 2 VI.Motor Unit VII. All or None Principle VIII. Innervation IX. Reciprocal Inhibition X. Factors Affecting Muscle Tension Development XI.Muscle Length - Tension Relationship XII.Proprioception HPER 205 1st Edition These 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. !XIII. Muscles Spindles XIV. Stretch Reflex XV.Golgi Tendon Organ Current Lecture A. Neural Control of Voluntary Movement1. CNS-central nervous systema. Brain and spinal cord2. PNS-peripheral nervous systema. Somatic and Autonomic- nervesB. CNS1. Cerebral Cortexa. voluntary muscle movement as aggregate muscles actions2. Basal Gangliaa. posture and equilibriumb. learned movements3. Cerebelluma. feedback controlb. timing and intensity of muscle movements4. Brain Stema. integrates all CNS activityb. arousal and maintenance of wakeful stateC. PNS1. Afferent system - carries nerve impulses from receptors toward CNS2. Efferent system - carries nerve impulses from receptors away from CNSD. Neurons1. Three classificationsa. sensoryb. motorc. interneuronsE. Neural Control of Voluntary Movement1. Neurons (nerve cells) - basic functional units of nervous systema. dendritesb. cell bodyc. axond. myelin sheathe. nodes of ranvierf. axon terminalF. Motor Unit1. Single motor neuron and all muscle fibers it innervates2. Function as a single unit3. Vary in size and numberG. All or None Principle1. Regardless of #, individual muscle fibers within a given motor unit will either fire and contract maximally or not at allH. Innervation1. A particular muscle has a specific nerve that it works with in regards to control of firinga. ex: long thoracic nerve and the serrates anteriorI. Reciprocal Inhibition1. Antagonist muscle groups must relax and lengthen when the agonist musclegroup contractsa. activation of motor units in agonists casuses a reciprocal neural inhibition of motor units in antagonistsb. this reduction in neural activity of antagonist allows lengthening under less tension- ex: immediate gains in strength when starting a resistance training programJ. Factors Affecting Muscle Tension Development1. Size of motor unit2. Number of muscle fibers per motor unit varies significantlya. less than 10 in small muscles- precise movementsb. more than a thousand in large muscles- perform less complex activities3. Total number of muscle fibers recruited can be increased by:a. activating larger motor unitsb. activating more motor unitsc. increasing the frequency of motor unit recruitmentK. Muscle Length - Tension Relationship 1. Greatest tension at resting length2. Tension is proportional to # of cross bridges connecteda. depends on overlap of myosin and actin3. Too long: cannot overlap and no cross bridges forma. passive insufficiency4. Too short: overlap too much and shortening cannot occurb. active insufficientlyL. Proprioception1. Def: subconscious mechanism that causes posture and movementa. responds to stimuli originating in proprioceptors of the joints, tendons, muscles, and inner ear2. Quality of movement and reaction to position change is dependent upon proprioceptive feedback from muscles and joints3. Proprioception may be enhanced through specific training4. Proprioceptors are specific to musclesa. Muscle spindles - detects muscle length- located in muscle belly and run parallel with fibersb. Golgi tendon organs - detects muscle tension- located in tendon close to muscle tendon junction5. Joint receptorsa. Kinesthetics receptors- Ruffini receptors+ joint capsule - stretch, possible emchanical pressure- Free nerve endings+ connective tissue - pain and mechanical pressure- Paciniform Corpuscles+ skin, tendons, joint capsules+ vibrationsM. Muscle Spindles1. Muscle spindles and stretch reflexa. rapid muscle stretch occursb. impulse is sent to the CNSc. CNS activates motor neurons of agonist muscle and causes it t ocontractN. Stretch Reflex1. Ex: knee jerk or patella tendon reflexa. reflex hammer strikes patella tendonb. causes a quick stretch of quadricepsc. muscle spindle activatedd. in response quadriceps fires and the knee extends2. More sudden the tap, the more signifier the reflexive contractionO. Golgi Tendon Organ1. Tension increases as muscle contracts, which activates GTOa. GTO stretch threshold is reachedb. Impulse is sent to CNSc. CNS causes agonist muscle to relax and activates antagonists as a protective mechanism2. GTO protects us from excessive