PSB Exam 4 Chapter 8 Study online at quizlet com 19ja41 1 Amyotrophic Lateral Sclerosis Gradual weakness and paralysis Unknown cause 8 Fast Twitch Fibers Fibers that produce fast contractions but fatigue rapidly Starts with arms spreads to legs then to other muscles Are anaerobic and use reactions that do not require oxygen resulting in fatigue UMNs LMNs axons of UMNs 2 Basal Ganglia A group of large subcortical structures in the forebrain responsible for initiating an action not guided by a stimulus Caudate nucleus Putamen Globus pallidus It has connections with the thalamus and cortex It decides what moves to make or inhibit 3 Cardiac Muscles Heart muscles that have properties of skeletal and smooth muscles 4 Causes of Huntington s Disease It is genetic autosomal dominant with a 95 penetrance Located on chromosome 4 with a trinucleotide repeate C A G The normal gene makes protein hunting tin The more it repeats the earlier it begins The earlier it begins the quicker it progresses 5 Causes of Genetics if early onset Parkinson s Disease Toxins MPTP MPP 6 Cerebellum Drugs increased use of cigarettes coffee leads to a decreased risk of PD and marijuana leads to increased risk of PD A structure in the brain often associated with balance and coordination There are more neurons in the cerebellum than in all other brain areas combined The cerebellar cortex is the surface of the cerebellum Important for tasks that require timing The cerebellum also seems critical for certain aspects of attention such as the ability to shift attention and attend to visual stimuli 7 Extensor Extends an appendage or straightens it Muscle Behaviors requiring quick movements utilize fast twitch fibers Flexes or raises an appendage Basal ganglia sends feedback for later control Brainstem has motor cranial nerves Spinal cord controls voluntary movement and reflexes When the motor cortex sends a signal to the periphery to cause movement it travels down the corticospinal tract AKA dorsolateral tract The cell bodies of the upper motor neurons UMN are in the motor cortex but the axon from an UMN descends via the brain stem and crosses over in the medulla to the other side of the body and then continue down the spinal cord until the UMN synapses on the lower motor neuron LMN or an interneuron in the spinal cord on the contralateral side from the motor cortex that sent the original signal The axon innervates more than 1 muscle fiber Eye muscles 1 axon innervates 3 fibers Biceps 1 axon innervates more than 100 fibers This difference allows the eye to move more precisely than the biceps The lower the fibers the more precise 9 Flexor Muscle 10 How are the cerebellum and the basal ganglia involved in movement 11 How does the motor cortex on one side control the movements for the contralateral side of the body 12 How many muscle fibers does a single neuron innervate and what does this mean for motion precision 13 Huntington s Disease The loss of dopaminergic cells in caudate putamen 14 Lateral Corticospinal Tract Symptoms Arm jerks facial twitches later tremors and writhing Also importantly cognitive changes and psychiatric symptoms Is the dorsolateral tract mostly from the primary motor cortex This controls movements in peripheral areas such as the hands and feet 15 Medial Corticospinal tract Includes axons from many parts of the cerebral cortex not just the primary motor cortex and surrounding areas Axons go to both sides of the spinal cord not just the contralateral side Controls mainly the muscles of the neck shoulders trunk and therefore movements such as walking turning bending standing up and sitting down Autoimmune demyelinating disease Unknown cause but could include genetics gender or environmental triggers viruses 16 Multiple Sclerosis 21 Prefrontal Cortex Responds to lights noises other sensory signals 22 Premotor Cortex Active during prep for a movement and during movement itself Gets info on location of target current body position 23 Proprioception Receptors that detect the position or movement of a part of the body Fluidity of movement 24 Reflexes Involuntary consistent and automatic responses to stimuli 25 Slow Twitch Fibers Fibers produce less vigorous contraction without fatigue 17 Muscle Spindles Muscle spindles are proprioceptors parallel to the muscle that responds to a stretch The muscle stretches which stretches the receptor then sends a message to the spinal cord which sends a message back to muscle fiber to contract This is the knee jerk reflex 26 Smooth Muscles 18 Myasthenia Gravis An autoimmune disease The immune system attacks Ach receptors at NMJs 27 Stretch Reflex 28 Structure and Parallel fibers excite Purkinje cells design of the Purkinje cells and parallel fibers in the cerebellar cortex 29 Supplementary Motor Most active just before rapid series of movements 30 Treatments of Parkinson s Disease Are aerobic and require oxygen during movement and therefore do not fatigue Non strenuous activities utilize slow twitch and intermediate fibers Control the digestive system and other organs Occurs when muscle proprioceptors detect the stretch and tension of a muscle and send messages to the spinal cord to contract it Purkinje cells transmit inhibitory messages to the cells in the nuclei of the cerebellum and the vestibular nuclei in the brain stem Messages are then sent to the midbrain and the thalamus L DOPA Other drugs antioxidants to decrease further damage neurotrophins to promote neuronal survival and growth and anti apoptotic Stimulation of GPi and nucleus subthalamicus which is good for decreasing tremor Stem cell transplants substantia nigra neurons or dopamine producing neurons in general Donor tissue might release neurotrophins that help neurons in recipient brain grow 19 Paralysis Paraplegia Quadriplegia Symptoms Rapid muscle fatigue It begins in the face and eventually can affect muscles used for breathing Treatment Immune suppressants or acetylcholinesterase inhibitors Paralysis lack of voluntary movement in some part of body Paraplegia lose sensation voluntary movement in legs Spinal cord damaged cut above leg segments Reflexes intact Genitals responsive orgasm possible Quadriplegia lose sensation voluntary movement in arms legs Damage to spinal cord above arm segments Control of breathing becomes a problem More D2 receptors on right but fewer dopamine terminals on right Symptoms Rigidity muscle tremors slow movement difficulty initiating movement or cognitive activity 20
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