Exam 3 November 10 2014 Lecture 13 Movement 1 Why do we and other animals have brains Important to drive or suppress future movements Everything we do our behavior is mediated by contractions of muscles Robots v Humans Cardiac 2 3 types of muscle tissue Walls of the heart Appear striated Involuntary control Smooth Skeletal Walls of hollow visceral organs e g GI tract except the heart Appears spindle shaped Involuntary control Attached to the skeleton Appear striated Voluntary control movement of the body in the environment 3 Skeletal Muscle fiber Mitochondria Sarcolemma Nucleus Myofibrils T tubule Terminal cistern Triad Sarcoplasmic Reticulum Each muscle is composed of many fibers Each fiber receives input from one axon One axon can innervate many fibers allowing for precision and coordination of movement 4 Fast twitch and Slow twitch Muscles Slow Twitch Slow contracting your muscle comp is genetic Efficient in using oxygen aerobic Delayed muscle firing prolonged Do not fatigue easily exertion non strenuous Best suited for endurance sports including cycling marathon running and long distance triatholons Fast Twitch Fast contracting Do not burn oxygen to create energy anaerobic Fast to fire best for explosive body movements Tire out quickly Best suited for short bursts of activity including sprinting races pole vaulting and cross fit style events 5 What happens when you work out You are stressing or damaging the muscle fibers micro tears in muscles usually in the lower phase hypertrophy Exam 3 November 10 2014 Muscle breakdown causes a build up of waste products and metabolites in the muscles cells like lactic acid creatine phosphokinase calcium ions and phospholipases These metabolites activate the mechanism unknown of the muscle growth to help stimulate anabolic hormonal production 6 Movement Anabolic hormones such as testosterone and HGH trigger muscle growth Ballistic Movement Executed as a whole that once commenced cannot be altered nor corrected by feedback most of our behaviors are influenced by feedback Central Pattern Generator Neural mechanisms in the spinal cord that generate rhythmic patterns of motor output e g walking breathing flying birds swimming fish scratching dog cats rhythmic motor pattern production Motor Program Fixed sequence of movements e g yawning smiling frowning raised eyebrows 7 Neuromuscular Junction Synapse between a motor neuron axon and a muscle fiber Synaptic vesicles containing acetycholine always excites the cell to contract 8 Action Potential process at the Neuromuscular Junction NMJ 1 Arrival of the AP at the NMJ 2 AP arrives at axon terminal 3 Ca ions rush in as AP activated Ca gates 4 Ca reacts with synaptic vesicles to cause them to fuse with the cell membrane 5 ACh acetylcholine is then released via exocytosis 6 ACh binds with motor end plate receptors depolarization occurs as Na rushes into the muscle cell along with Ca Impulse travels through T tubules to ultimately cause the muscle to move 7 9 Muscle Control by Proprioceptors What is proprioception again Our bodies enable us to adjust your posture and maintain your balance Proprioceptor detects the position or movement i e stretch and tension of a part of the body i e muscle and relays to the spinal cord to adjust the body s position i Golgi Tendon Organ responds to increases in muscle tension by exciting interneurons in the spinal cord to act as breaks for muscle contraction to prevent damage Stretch Reflex reflex caused by a stretch that results in contraction of a muscle via a muscle spindle Muscle Spindle receptor that is parallel to the muscle that responds to a stretch i Muscle spindle is stretched sensory nerve signals a motor neuron in the spinal cord contraction 10 Voluntary Involuntary Movements Reflexes consistent automatic responses to stimuli Exam 3 November 10 2014 i Pain receptors sensory neuron spinal nerve dorsal root ganglion cell body of sensory neuron cell body of association neuron association neuron cell body of motor neuron ventral root motor neuron effector muscle Insensitive to reinforcements punishments and motivation 1 Gasp reflex 2 Babinski reflex 3 Rooting reflex 11 Movement in the Brain Motor cortex is the precentral gyrus 1 Motor Cortex axons 2 Medulla 3 Spinal cord 4 Muscles Cerebral Cortex involved in complex action and not so much less complex actions Motor Area muscle voluntary movement Basal Ganglia coordination movement Cerebelum balance coordination and precision of movement Hippocampus learning memory Primary motor cortex movement maker Posterior parietal cortex position of the body in the environment proprioception and movement planning intention Damage here means difficulty in finding objects Supplementary motor cortex planning and organizing a rapid sequence of movements also inhibits habitual movements Premotor cortex active immediately before a movement also position and posture of the body Prefrontal cortex stores sensory information essential to movement considers possible outcomes of movements Damage here means illogical movements i e showering with your clothes on Can be blamed for absent mindedness in that it is not fully awake 12 Mirror Neurons Active in prep of movements or watching someone do a similar movement Found in the premotor cortex frontal cortex insular cortex Important for understanding identifying and imitating other people Insular cortex cells active when you are disgusted or see something disgusting or someone disgusted 13 Conscious Decisions and Movements What happens in your brain when you move Do you decide to move and the move Motor cortex produces a readiness potential before any voluntary movement that is active at least 500 ms prior to the movement Exam 3 November 10 2014 Basically your brain fires before you are conscious of your decisions to move 14 Movement in the Brain Motor cortex is the precentral gyrus Corticospinal Tract Motor cortex axons Midbrain red nucleus here controls arm muscles Spinal Cord Muscles Cerebral cortex involved in complex actions and not so much less complex actions 15 Cerebellum Contains more neurons than the rest of the brain combined Must be important huh Important for aim timing alternating movements basically every sport but weight lifting and continuous motor activity sensory stimuli touch and attention Essentially thought to establish new motor programs for executing a sequence of actions as a whole with precise timing 16 Cells of the Cerebellum Receives input from the spinal
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